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Pharm > Exam 4 > Flashcards

Exam 4 Flashcards

1
Q

What four characteristics are antimicrobial drugs classified by

A

1) Class of microorganism to which they show activity
2) Antibacterial spectrum of activity
3) Bacteriostatic or bactericidal
4) Time or Concentration-dependent activity

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2
Q

Broad spectrum antimicrobials

A

active against a wide range of bacteria and potentially active against mycoplasma, rickettsia, chlamydia, protozoa

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3
Q

Narrow spectrum antimicrobials

A

antimicrobials that only inhibit bacteria

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4
Q

Narrow spectrum antibacterials

A

may only inhibit gram positive or gram negative bacteria

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5
Q

Broad spectrum antibacterials

A

inhibit both gram positive and gram negative and potentially aerobic and anaerobic bacteria

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6
Q

All antimicrobials are _________ at low concentrations and stop organisms from multiplying but do not call

A

Bacteriostatic

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7
Q

What are some classes of antimicrobials that are bacteriostatic at all concentrations

A

tetracyclines and sulfonamide

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8
Q

Some antimicrobials are capable of being _______ if high enough concentration

A

Bactericidal. almost always dependent upon target bacteria multiplying at time of the drug exposure

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9
Q

Minimum inhibitory concentration (MIC)

A

the lowest concentration of a drug required to inhibit visible growth of bacteria in a test tube
-Determined using a dilution test

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10
Q

Minimum bactericidal concentration

A

the minimum concentration of a drug required to inhibit visible growth of bacteria in a test tube (Can be 2-4x or more the MIC value)

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11
Q

What is the breakpoint MIC

A

the value above which plasma concentrations are unlikely to be achieved and thus clinical benefit is unlikely with labeled dosing

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12
Q

What is the relationship between MIC and breakpoint values

A

how the minimum inhibitory concentration is used to determine if a particular infection is likely to be clinically sensitive, intermediate, or resistant

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13
Q

How do you select an antimicrobial agent based on MIC and breakpoint values

A

you want the agent MIC to be sensitive (S) , and be able to move 2 clicks and still be sensitive

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14
Q

Post-Antibiotic effect

A

the persistent inhibition of bacterial growth by an antimicrobial agent even when drug levels become below its MIC
-delayed re-growth of surviving bacteria

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15
Q

How would you measure concentration dependent activity of an antimicrobial

A

The concentration peak (Cmax) of the serum
ex: aminoglycosides

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16
Q

How would you measure both concentration and time dependent activity of an antimicrobial?

A

The area under the curve (AUC)
ex: fluoroquinolones

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17
Q

What is an example of an antimicrobial that is time dependent

A

beta lactams

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18
Q

What is an example of an antimicrobial that is concentration and time (AUC) dependent?

A

fluoroquinolones

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19
Q

What is an example of an antimicrobial that is concentration dependent

A

aminoglycosides

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20
Q

How might you minimize the Cmax of a drug?

A

give a lower dose more frequently

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21
Q

How might you achieve T>MIC

A

lower dose more frequently to acheieve a lenght of time where serum concentrations exceed the minimum inhibitory concentration (MIC)
ex: Beta lactams, some macrolides, tetracyclines, TMS, chloramphenicol

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22
Q

What does time dependent activities mean

A

the length of time spent above the MIC matters, increasing the concentration several fold above the MIC does not significantly increase microbial killing
think: betalactams, some macrolides, tetracyclines, TMS, chloramphenicol

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23
Q

What does concentration dependent activities mean

A

the maximum serum concentration achieved is the most significant factor determining the efficacy of some drugs such as Aminiglycosides, metronidazole, +/- fluoroquinolones

*Rate of killing increases as drug concentration increases further above MIC, not necessarily or even beneficial to maintain drug levels above MIC between doses

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24
Q

How can you optimize Cmax/MIC

A

give a higher dose less frequently

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25
Q

What does both time and concentration dependent activities mean?

A

some drugs exert characteristics where best predictor of efficacy is the 24hours area under the serum concentration versus time curve to MIC ratio (AUC/MIC)
ex: gylcopeptides, rifampin, and to some extent the fluoroquinolone

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26
Q

What dosing schedule is most likely to be used with both time and concentration based activities

A

once a day (qD) or twice a day
as long as AUC/MIC is reached in both regiments

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27
Q

What dosing is best for time dependent?

A

lower dose more frequently

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28
Q

Why might you combine antimicrobial drugs together

A

1) Antimicrobial synergism
2) Polymicrobial infection
3) Decrease emergence of resistant isolates
4) Decrease dose-related toxicity

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29
Q

Additive/Indifferent interaction

A

the activity in combination equals the sum of separate independent activities
may not be economically justifiale

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30
Q

Synergistic effect

A

activity of the combined antimicrobial agents is significantly greater than the sum of the independent activites

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31
Q

Antagonistic effect

A

activity of the combination is significantly less than the sum of the independent activities

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32
Q

Reasons you might choose an antibiotic

A

1) Identify organism at site of infection
2) Knowledge of usual susceptibility profile
3) Knowledge of factors that affect drug concentration at the site of infection
4) Knowledge of drug toxicity and factors that enhance it
5) Cost of treatment
6) Knowledge of regulations about the use of a drug including withdrawal times when appropriate

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33
Q

Ciprofloxacin is a ___________

A

fluoroquinolone

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34
Q

Enrofloxacin is a__________

A

fluoroquinolone

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35
Q

Marblofloxacin is a _________

A

fluoroquinolone

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36
Q

Pradofloxacin is a ________

A

fluoroquinolone

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37
Q

What is the mechanism of fluoroquinolones?

A

-inhibition of bacterial DNA gyrase and/or topoisomerase IV leading to the inhibition of DNA supercoiling and replication
-Enter the cell via porins and accumulate rapidly inside susceptible bacteria
-Concentration dependent (Cmax:MIC or AUC:MIC)
-Post-antibioitc effect in enrofloxacin and orbifloxacin

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38
Q

All fluoroquinolones discussed end with:

A

-floxacin

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39
Q

Fluoroquinolones are best absorbed via:

A

oral route

-decreased absorpotion if high concentrations of divalent/trivalent cations (ex: antacids, nursing young)
-poor absorption orally in ADULT ruminants

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40
Q

What can decrease the absorption of fluoroquinolones?

A

if high concentrations of divalent/trivalent cations (ex: antacids, nursing young)

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41
Q

What fluoroquinolone is best absorbed in horses?

A

Enrofloxacin, Ciprofloxacin is poorly absorbed

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42
Q

Fluoroquinolone distribution

A

achieve concentrations at tissues as high as plasma

*reaches therapeutic doses from gram - organisms in the CNS and eye

  • Rapidly accumulate in macrophages and neutrophils may lead to higher concentrations in infected tissues compared to healthy

-Urinary and prostate accumulation

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43
Q

In many species, Enrofloxacin is metabolized to form

A

ciprofloxacin via de-ethylation
(up to 40% in the dog)

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44
Q

Generations of quinolone drugs

A

1st: older drugs (nalidixic acid, flumequine) - activity restricted to enterobacteriaceae

2nd: all but one vet quinolone, extended spectrum of activity but limited against Streptococci and obligate anaerobes

3rd: Pradofloxacin
Improved in-vitro activity agaisnt Streptococci and obligate anaerboes

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45
Q

What is the only vet med quinolone to be 3rd generational?

A

Pradofloxacin, imporved activity against Streptococci and obligate anaerobe

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46
Q

2nd generational quinolones have an extended spectrum of activity but are limited against:

A

Streptococci and obligate anaerobes

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47
Q

Why can therapeutic concentration of ciprofloxacin be reached with dosing calculated to achieve effective enrofloxacin concentrations

A

Because MICs for ciprofloxacin are often lower lower than those for enrofloxacin

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48
Q

Fluroquinolones have activity against:

A

Good:
Gram - aerobes including enterobacteriaceae (E coli, Klebsiella, Proteus, Salmonella, Actinobacillus, Brucella, Leptospura, Pasteurella), Mycoplasma, Rickettsia

Moderate/Variable Activity:
Gram + aerobes: Streptococci (agalactiae, suis, zooepidemicus) Rhodococcus, mycobacteria

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49
Q

Anaerobic Bacteria are normally resistant against all fluoroquinolones except?

A

Pradofloxacin

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50
Q

Generally, all fluoroquinolones (except Pradofloxacin) are better is aerobes or anaerobes?

A

aerobes (gram - more than +)

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51
Q

T/F Fluoroquinolones have mycoplasma spp. activity

A

True

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52
Q

What is a consequence of enrofloxacin in cats when doses are higher than 5mg/kg/day

A

-Retinal degeneration due to reduced function of ABCG2/BCRP efflux transporter in cat retina leading to drug accumulation and photoreaction

Also neurotoxic effects have been reported

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53
Q

What is a result of fluoroquinolone admin. during immature animals

A

-Arthropathies and cartilage erosion in weight bearing joints (immature cats, dogs, and horses)
Avoid use in small and medium dogs during rapid growth

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54
Q

What fluoroquinolone has a greater BBB penetration and more likely to cause neurotoxic effects through GABA receptor inhibition

A

Enrofloxacin

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55
Q

How can enrofloxacin cause neurotoxic effects

A

through GABA receptor inhibiton

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56
Q

What can be a result of most antimicrobial agents in horeses

A

enterocolitis

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57
Q

What drugs have antagonism effects with ciprofloxin/enrofloxin?

A

chloramphenicol and rifampin

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58
Q

What are the four main categories of resistance to fluoroquinolones

A

1) Target modification
2) Decreased permeability
3) Efflux
4) Target protection

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59
Q

Target modification resistance to fluoroquinolones

A

Stepwise Mutation in DNA gyrase (gyrA mutation) with secondary mutations of Topo IV (parC mutation)

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60
Q

Why does Campylobacter have a higher resistance to fluoroquinolones

A

because it does not have Topoisomerase IV and thus a single mutation can lead to high level of resistance because it only needs a mutation in DNA gyrase
why fluoroquinolones are banned in poultry production

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61
Q

Why are fluoroquinolones banned in poultry production

A

because they do not have Topo IV so only a single mutation in DNA gyrase is needed for resistance

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62
Q

What factors lead to fluoroquinolone resistance through reduced intracellular drug levels

A

1) Altered outer membrane porins- decrease permeability of cell wall to drug
2) Induced membrane efflux pumps- removing the drug before they can interact with DNA gyrase and Topo IV

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63
Q

How does target protection resistance to fluoroquinolones occur?

A

quinolone resistance gene qnr functioning to protect DNA gyrase (not Topo IV) from inhibition by fluoroquinolones
result in small decrease in drug susceptibility

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64
Q

How does the qnr gene protect bacteria from quinolones

A

it protects DNA gyrase, not Topo IV

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65
Q

How do you reduce emergence of resistance to fluoroquinolones

A

targeting the dosage to the MIC of the pathogen to the clinical resolution of infection

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66
Q

Pharmacokinetic properties of quinolones

A

good oral absorption
large volume of distribution
good intracellular drug penetration
extended elimination half lives allow for every 24-48 hour

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67
Q

How were beta lactams discovered?

A

in 1928 when Penicilium mold lysed colonies of staph
1940: isolated into powder
1945: Cephalosporing C from Cephalsosporium acremonium

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68
Q

What improves the pharmacokinetic properties of beta-lactam?

A

substitiutions on the beta-lactam ring increases resistance to beta-lactamase enzymes, enhances activity and improves properties

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69
Q

Penicillin G is a _________

A

natural penicillin (beta-lactam)

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70
Q

Ampicillin is a _______

A

amino penicillin (beta-lactam)

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71
Q

Amoxicillin is a ________

A

amino penicillin (beta-lactam)

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72
Q

Oxacillin is a _______

A

anti-staphylococcal penicillin (beta-lactam)

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73
Q

Piperacillin is a __________

A

extended spectrum penicillin

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74
Q

What is the mechanism of action of penicillins?

A

prevention of cell wall formation and cause lysis of bacterial cells to produce a bactericidal action
-slower kill rates than fluoroquinolones

inhibition of peptidoglycan synthesis through interfering with penicillin-binding proteins (peptidoglycan active enzymes)

Bactericidal only for growing cells (those undergoing active cell wall synthesis

*4 member ring of beta lactam mimics D-Ala peptide terminus that serves as a natural substrate for transpeptidase activity during cell wall synthesis, blocks covalent bonds and weakens wall leading to lysis due to high internal osmotic pressure

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75
Q

4 ways beta-lactams differ in their gram + vs - activity

A

1) Differences in receptor sites on PBPs
2) Relative amount of peptidoglycan present
3) Ability to penetrate outer cell membrane of gram -
4) Resistance to the different types of beta-lactamase enzymes present

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76
Q

Are beta-lactams time or concentration dependent

A

TIME DEPENDENT- the length of time that antibiotic concentrations at the site of infection exceed the MIC (T<MIC) should be at least 50-60%
doses more frequently than concentration dependent drugs like fluoroquinolones

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77
Q

What is the eagle effect with beta-lactams?

A

When concentrations are above the optimal killing concentration, result in reduced bactericidal effect due to binding to PBPs that cause growth arrest; the failure to grow results in failure to be killed by antibiotic
*tendency to overdose with these drugs due to large safety margin

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78
Q

What is the primary mechanism of resistance to beta-lactams?

A

the production of beta-lactamase enzymes (Serine and Metallo beta-lactamases
these break the beta-lactam ring destroying the pharmacore
extracellularly produced (gram +)
periplasmic produced (gram -)

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79
Q

Beta-Lactamase Enzyme Inhibitors

A

block resistance to beta-lactams via beta-lactamase enzymes to inhibit them
-Avibactam
-Clavulanic acid
-Tazobactam

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80
Q

Clavulanic acid is a ______

A

Beta-lactamase enzyme inhibitor

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81
Q

Avibactam is a ________

A

Beta-lactamase enzyme inhibitor

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82
Q

Tazobactam is a ______

A

Beta-lactamase enzyme inhibitor

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83
Q

Why are penicillins poorly absorbed orally

A

because they are acid labile

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84
Q

Why do you need to frequently dose penicillins

A

because of short half life/rapid elimination and time dependent activity

do not cross biologic membranes easily

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85
Q

What effect does impaired renal function have on elimination of penicillins

A

it is eliminated almost entirely through renal excretion but you do need to adjust dosage because of wide safety margin

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86
Q

Penicillin G

A

a natural penicillin
mostly active against gram + aerobes and anaerobes (less against Staphylococcus, Gram - and enterobacteriacea are generally resistant)

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87
Q

What can occur with Penicillin G toxicity

A

rare but often hypersensitivity reaction, can cayse anaphylaxis in sensitive individuals - potassium

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88
Q

What form of Natural/benzyl penicillins can be orally absorbed

A

Penicillin V- it resists acid hydrolysis and is administered orally
same spectrum as other benzyl penicillins

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89
Q

Procaine penicillin

A

slowly absorbing penicillins
DO NOT USE ON BIRDS, SNAKES, TURTLES, GUINEA PIGS, OR CHINCHILLAS

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90
Q

What species should you you not use procaine formulations on?

A

-Birds
-Snakes
-Turtles
-Guinea pigs
-Chinchillas

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91
Q

What is the spectrum of activity of ampicillin and amoxicillin

A

Increased to include many gram - aerobes (E Coli, Proteus, Pasteurella)

Slightly less activity than Pen G against Gram + an anaerobes

Acid stable with amoxicillin having a greater bioavailability than ampicillin

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92
Q

What beta-lactams are resistant to beta-lactamases produced by Staph aureus and used in the treatment of bovine staphylococcal mastitis

A

-Cloxacillin, Dicloxacillin, Oxacillin, Methicillin

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93
Q

What penicillin is used to test methicillin sensitivity in vitro

A

oxacillin

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94
Q

MRSA/MRSP

A

methicillin resistant staphylococcus that is resistant to all beta-lactams due to mecA gene producing an alternative PBP (PBP2A)

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95
Q

All other penicillins do not have activity against Pseudomonas except…

A

Carbenicillin, Ticarcillin, and Piperacillin (Antipseudomonal/Extended Spectrum Pencillins)

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96
Q

What can be used for treatment of otitis externa in dogs caused by Pseudomonas aeruginosa

A

Ticarcillin

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97
Q

Why should you not give Ampicillin to small rodents and rabbits

A

potential for disturbing normal intestinal flora
and can produce Clostridial colitis

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98
Q

What is the best penicillin for the treatment of urinary tract infections

A

Amoxicillin

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99
Q

What is the drug of choice for treating leptospirosis

A

Amoxicillin (because it is a gram negative aerobe)

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100
Q

What are the drugs of choice for mixed aerobic/anaerobic infections such as cat-bite infections

A

Ampicillin or amoxicillin

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101
Q

T/F Cephalosporins are more susceptible to beta-lactamase enzymes than beta-lactams

A

F

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102
Q

What route do cephalosporins typically require?

A

Parenteral, short-half life-require frequent dosing
poor intracellular penetration

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103
Q

Are cephalosporins time dependent or concentration dependent?

A

Time dependent

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104
Q

Are cephalosporins bacteriostatic or bacteriocidal?

A

Bactericidal

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105
Q

In general as you increase the cephalosporing generation: coverage increase from-

A

gram + coverage to gram - coverage (but at the cost of gram + coverage)

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106
Q

How does cephalosporin resistance occur?

A

Same as pencillins
1) PBP modification
2) Reduced permeability and increase efflux
3) Beta-lactamase production (important)

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107
Q

1st generation cephalosporins activity

A

Good activity: Gram + aerobes, including lactamase prodicing staphylococcus and streptococcus

Moderate: Gram - enterobacteriacea

No activity against Pseudomonas or Enterobacter

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108
Q

Cefazolin, Cephapirin, Cephalothin (Injectable)

Cephalexin and Cefadroxil (oral)

A

1st generation cephalosporins

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109
Q

Why might you use 1st generation cephalosporins?

A

skin and urinary tract infections and other non-specific infections caused by staphylococci and streptococci (good gram + aerobe activity), enterobacteriacea and some anaerobes

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110
Q

How do the different Cephalosporins differ in their route of admin

A

1st gen: Oral or injectable
2nd gen:Parenteral (no oral)
3rd gen: injectable

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111
Q

How do 2nd generation Cephalosporins differ from 1st gen?

A

they have slightly more gram - and anaerobe coverage with slightly less gram + coverage than 1st gen

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112
Q

Cephamycins

A

2nd generational cephalosporins that are derived from Streptomyces rather than Cephalosporium (Cefotetan and Cefoxitin) and very stable to beta-lactamases

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113
Q

Cefoxitin

A

a 2nd generation cephalosporin
(derived from Streptomyces)
treat severe mixed infections with anaerobes such as aspiration pneumonia, bite infections, peritonitis, and prophylaxis in colonic surgery or ruptured intestine

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114
Q

What category is Cefoxitin?

A

a 2nd generational cephalosporin
(derived from Streptomyces)

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115
Q

What is the Cephalosporin with best activity against Pseudomonas

A

Ceftazidime

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116
Q

Ceftazidime

A

a 3rd generation cephalosporin (extended spectrum of activity against gram - and some anaerobes)
*good activity against pseudomonas

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117
Q

Ceftiofur

A

a 3rd generational cephalosporin used for respiratory disease of cattle, sheep, swine, and horses
urinary tract infections in dogs
(naxcel) is a slow releasing injectable form

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118
Q

Cefovecin

A

a 3rd generational cephalosporin named Convenia
SQ injection for cats and dogs that can used as a single treatment
high MIC for Staph pseudointermedius for 14 days

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119
Q

Cefpodoxime

A

Simplifcef- a 3rd generational cephalsporine
prodrug - esterified in GI tract to release active cefpodoxime
longer half life than other cephalosporins
*No Pseudomonas activity unlike other 3rd generational

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120
Q

What are the two 3rd generational Cephalosporins that do not have activity against Pseudomonas

A

1) Cefpodoxine
2) Cefovecin

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121
Q

What 3rd generational cephalosporins have activity against Pseudomonas and which ones dont

A

DO: Ceftiofur, Cefovecin (Convenia)

DONT: Cefpodoxime and Cefovecin

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122
Q

T/F 3rd and 4th generation cephalosporins are not first line drugs for uncomplicated infections

A

T

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123
Q

Convenia and Simplicef are often used as a first line of drugs for skin and urinary tract infections because of less frequent dosing. Why is this bad

A

They are 3rd generational cephalosporins
-Most cat bite infections can be successfully treated with amoxicillin (Clavamox)
-Most staphylococcal skin infections can be treated with cephalexin and a 3rd gen is not needed

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124
Q

Cephalexin

A

a 1st generational cephalosporing that is often used staphylococcal skin infections because of its good activity against gram + aerobes

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125
Q

Why should you be careful with 3rd and 4th generational cephalosporins

A

because they are extended spectrum and have the ability to induce super beta-lactamses in bacteria that render them highly resistant and thus no beta-lactams may be effective
*Big concern - banned for extralabled use in food animals

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126
Q

Carbapenems

A

derivatives of streptomyces spp.
Widest activity of any antibiotic, except trovafloxacin
Activity against almost all clinically important aerobic or anaerobic gram + or gram - cocci or rods
Resistant to almost all bacteria beta-lactamase enzymes
All are pareneterally
Last resort in human med

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127
Q

Imipenem

A

a carbapenem that is rapidly hydrolyzed by a dehydropeptidase in th renal tubules to a nephrotoxic compound

Always administered with cilastatin to inhibit dihydropeptidase and prevent nephrotoxicity

IV only

Tx of ESBL producing Enterobacteriacea when a single drug is required

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128
Q

What should you give with Imipenem to prevent nephrotoxicity by inhibiting dihydropeptidase

A

Cilastatin

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129
Q

Cilastatin is commonly given with _______ to prevent nephrotoxicity

A

Imipenem

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130
Q

Meropenem

A

a carbapenem that is sometimes used off label (use SQ instead IV)
Similar activity to imipenem
not a first line of drug

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131
Q

T/F Carbapenems can be used as a first line of drug

A

F

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132
Q

What should you combine with Carbapenems for treatment of Pseudomonas to reduce resistance potential

A

Aminoglycoside

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133
Q

Aztreonam

A

a monobactam
stable to most beta-lactamase enzumes
Almost all gram - aerobes

resistance seen in gram + and anaerobes

Potential for use as substitute for more toxic aminoglycoside for mixed infections

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134
Q

What is the potential use of Aztreonam?

A

sunstitute for the more toxic aminoglycoside for tx of mixed infections

-With clindamycin/Metronidazole for mixed aerobic/anaerobic infections

-With erythromycin in mixed infections where gram + organisms are present

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135
Q

What is clavulanic acid used for?

A

in combination with beta-lactam antibiotics to block resistance via beta-lactamase enzymes to inhibit them

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136
Q

What are the three classes of protein synthesis antimicrobials?

A

1) Tetracyclines
2) Chloramphenicol
3) Aminoglycosides

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137
Q

How do protein synthesis antimicrobials work?

A

By binding to either the 30S or 50S ribosomal subunit to inhibit the formation of polypeptide chains and block protein synthesis

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138
Q

Chloramphenicol binds to the _______

A

50S ribosomal subunit and inhibits the formation of peptide bond

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139
Q

Tetracyclines mechanism of action

A

interfere with the attachment of tRNA to mRNA ribosome complex
30S small ribosomal unit

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140
Q

Tetracycline spectrum of activity

A

Gram + and _ bacteria
Mycoplasma
Some mycobacteria
Most a-proteobacteria (Anaplasma, Rickettsia)
Protzoan and filarial parasites

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141
Q

What do tetracycline bind to

A

16S rRNA and S7 protein of the 30S ribosomal subunit

inhibits rRNA from binding to the docking site on the ribosome and mRNA codon to block peptide synthesis

also have anti-inflammatory activity- inhibit metalloproteinase enzymes, can scavenge reactive oxygen species (ROS)

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142
Q

What class is Doxycycline

A

a tetracycline- binds 30S subunit

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143
Q

Are tetracyclines bacteriocidal or bacteriostatic

A

generally bacteriostatic

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144
Q

What are the main mechanisms of Tetracycline resistance

A

1) Energy dependent efflux systems that exchange an extracellular H+ for a drug-Mg2+ complex
2) Ribosomal protection proteins that remove the tetracycline from binding site near the tRNA docking site
*flavin preventing cation chelation and ribosomal bind
*16S rRNA mutation
*Stress-induced down regulation of porins which drugs use to enter gram - walls

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145
Q

What is one of the few antimicrobials drugs that is osteotropic

A

Tetracyclines

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146
Q

What can reduce the already poor oral bioavailability or tetracyclines?

A

milk replacer or antiacids

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147
Q

Why do tetracyclines have longer half lifes

A

although it excreted primarily through glomerular filtrations it enter enterohepatic circulation

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148
Q

What antimicrobial is associated with esophageal strictures in cats?

A

Doxycycline tablets

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149
Q

What antimicrobial is associated with yellow discoloration of the teeth

A

Tetracycline

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150
Q

Tetracycline toxicity

A

1) Irritants- vomiting (oral), tissue damage
2) Enterocolitis = imbalance of intestinal flora
3) Esophageal stricture cats (tablets)
4) Acute heart toxicity (binding calcium)
5) Renal toxicosis with high dose
6) Yellow discoloration of teeth

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151
Q

What is the drug of choice for treating Rickettsial infections

A

Doxycycline

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152
Q

What is the treatment of choice for Chamidophilia felis

A

Doxycycline

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153
Q

What are the clinical implicatons of tetracyclines

A

1) Bovine/porcine respiratory disease complexes
2) Plague, tularemia, and listeriosis
3) Rickettsia
4) Chlamidophilia felis

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154
Q

What does Chloramphenicol bind to?

A

the 50S subunit of bacterial ribsome and inhibits peptidyl transferase to growing peptide

also inhibits mitochondrial protein synthesis in bone marrow

generally bacteriostatic

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155
Q

Chloramphenicol is bacteriocidal or bacteriostatic?

A

Bacteriostatic

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156
Q

Chloramphenicol isborad spectrum but what does it have poor activity against

A

Mycobacterium
Nocardia
resistance to gram - enterics like e coli

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157
Q

Chloramphenicol spectrum of activity

A

broad spectrum

good: gram positive aerobes including Actinmyces, Bacillus anthracis, MRSP NA strainsl gram - aerobes and anaerobes including Bacteriodes and Clostridium

Intermediate activity: rhodococcus equi

Poor activity: Mycobacterium spp, Nocardia, resistance often develops with gram - enterics such as E coli

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158
Q

What is the most frequent mechanism of resistance to chloramphenicol

A

enzymatic inactivation by acetylation of the drug by bacterial chloramphenicol acetyltransferases (CAT)- common on enterbacteriacea and Pasterurellacea

also efflux of drug from bacterial cells by either specific or multirug transporters

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159
Q

Chloramphenicol PK properties

A

rapidly absorbed from oral and parenteral administration
Wide distribution with effective concentrations in almost all tissues including CNS and eye

Hepatic metabolism with conjugation to glucuronic acid (glucuronidation) leads to widely variable elimination half-life across species

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160
Q

Why is Chloramphenicol activity prolonged in cats

A

due to limited glucuronidation capacity

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161
Q

What are the toxic effects of chloramphenicol

A

1) inhibitor of cytochrome p450 enzymes= interaction. fatal if with phenobarbital
2) Bone marrow suppression due to inhibition of mitochondrial protein synthesis, dose depedent bone marrow suppression

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162
Q

What is the main toxicity of chloramphenicol

A

bone marrow suppression

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163
Q

T/F Chloramphenicol is not okay to use in food animals

A

T, use florfenicol instead

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164
Q

What should be used instead of chloramphenicol in food animal settings?

A

Florfenicol

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165
Q

What are the clinical applications of Chloramphenicol?

A

*Serious ocular infections, prostatitis, otitis media/interna and salmonellosis in horses, dogs, and cats

-Treatment should NOT exceed 10 days, especially in cats

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166
Q

What is one of the few antimicrobial drugs that can be safely administered to horses by mouth?

A

Chloramphenicol

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167
Q

Are aminoglycosides bactericidal or bacteriostatic

A

bactericidal

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168
Q

What is the mechanism of action of aminoglycosides

A

inhibit protein synthesis by binding to the 30S ribosomal subunit (same as tetracyclines) and cause misreading of the genetic code

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169
Q

What true classes of antimicrobials bind to the 30S subunit?

A

Tetracyclines
Aminoglycosides

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170
Q

Florfenicol is a _______

A

Acetamide (same as chloramphenicol)

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171
Q

Why is combining a cell wall inhibitor with aminoglycoside synergisitic?

A

Because aminoglycosides need to penetrate the bacterial cell wall first

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172
Q

What group of microbes are aminoglycosides not as effective against and why?

A

-Anaerobes
*Bacteria need to actively pump aminoglycosides into the cell via an oxygen-dependent mechanism

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173
Q

Are aminoglycosides time or concentration dependent

A

Concentration dependent- target concentration needs to be at least 10x the MIC
Significant post-antibioitic effect where when concentration have dropped, bacteria are more susceptible to host defenses

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174
Q

What environment increases the activity of aminoglycosides?

A

alkaline environments
-alkalizing the urine will increase efficacy for UTI treatment with aminoglyosides

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175
Q

What is the spectrum of activity of aminoglycosides?

A

Primarily against Aerobic, gram - bacteria
some gram + are also (Staph more than Strep, strep efficacy can be increases with beta-lactam)

NOT effective against anaerobic bacteria

176
Q

What group of antimicrobials end with -amycin/amicin

A

aminoglycosides or macrolides idk

177
Q

Gentamicin is a ______

A

aminoglycoside

178
Q

Amikacin is a ______

A

aminoglycoside

179
Q

Tobramycin is a ______

A

aminoglycoside

180
Q

What aminoglycoside is highest in potency, spectrum of activity, and stability against enzyme-mediated inactivation

A

*Amikacin > tobramycin > gentacin >Neomycin = kanmycin > streptomycin

181
Q

How does aminoglycoside resistance often occur?

A

in form of plasmid-mediated enzymes that acetylate the aminoglycoside which prevents it from binding to the 30S ribosomal subunit

*also reduced reuptake via first exposure adaptive resistance

182
Q

T/F aminoglycosides are best absorbed orally

A

F- poor oral absorption- almost all application require parenteral administration

183
Q

All aminoglycosides cause varying degrees of __________ toxicity

A

Ototoxicity (vestibulocochlear)
Nephrotoxicity

184
Q

What is the most common adverse effect of aminoglycoside therapy?

A

*Acute tubular necrosis

also some defree of ototoxicity and nephrotoxicity

Rapid IV admin-bradycardia and reduced blood pressure
neuromuscular blockade is rare but if given post surgery can potentiate the effects of other non-depolarizing NMJ blocking- treat with Ca-chloride or Ca-gluconate

185
Q

Where do aminoglycosides accumulate and cause damage?

A

proximal tubular cells leading to acute tubular necrosis

not associated with peak concentration but duration of therapy, number of doses per day, volume depletion, acidosis, age, and elevated trough concentrations

186
Q

What three ways might you reduce the nephrotoxicity of aminoglycosides?

A

1) Calcium supplementation (cations displace/prevents cationic drug from binding to anionic phsopholipid

2) Feeding high-protein diet such as alfalfa and >25% in small animals- also increases GFR and renal blood flow which reduces aminoglycoside accumulation

3) administer once-daily in higher doses, allow trough concentrations to drop below critical level before next dose

187
Q

What should be monitored during aminoglycoside administration?

A

therapeutic drug monitoring to evaluate plasma concentration to ensure that trough concentrations are appropriate before the next dose.
sample 1 and 8 hr after dosing t. increases elimination half life is a very senstivie indicator of early tubular insult
Also monito using increase in urine GGT, GGT:creatinine ratio, development of proteinuria, elevations in BUN and creatinine are not seen until at least 7 days

188
Q

Neomycin

A

an aminoglycoside (30S) that is toxic and largely restricted to topical or oral use for treatment of enterobacteriacea

189
Q

Why might you use aminoglycosides?

A

Toxicity so limited use
-Neomycin restricted to topical or oral use
-Less toxic reserved for parenteral treatment of severe sepsis caused by gram - aerobes and the treatment of MRSP infections

190
Q

What are macrolide mechanism of action

A

protein synthesis inhibitor- irreversibly bind to 50S subunit (like chloramphenicol) and prevent transpeptidation and translocation leading to premature detachmenet of incomplete polypeptide chains
generally bacteriostatic
immunomodulatory effects (independent of antimicrobial effects)- inhibit chemotaxis and infilatrion of neutrophils into the airway, decreasing mucous secretion
inhbit production of numerous pro-inflammatory cytokines IL-1,6,8, TNFa
pro-kinetic effect on gi tract (motilin agonist)

191
Q

What three classes of drugs irreversibly bind to the 50S ribosoome and prevent transpeptidation and translocation leading to premature detachment of incomplete polypeptide chains

A

Macrolides, Chloramphenicol, Oxazolidinones

192
Q

Are macrolides bactericidal or bacteriostatic?

A

Generally bacteriostatic. can be -cidal at high concentration and against low inoculum of highly susceptible bacteria
anti-biofilm activity of some macrolides

193
Q

What are the two immunomodulatory effects of macrolides?

A

1) Inhibit chemotaxis and infiltration of neutrophils into the airway which subsequently decreases mucous secretion
2) Inhibit the production of numerous pro-inflammatory cytokines (IL-1, IL-6, IL-8)

194
Q

What group of antimicrobials have a pro-kinetic effect on the gi tract of dogs, horses, and cattle

A

Macrolides - direct motilin receptor agonist
Erythomycin in horses and dogs
Erythomycin, tylosin, tilmicosin in cattle

195
Q

Erythromycin is a ______________

A

Macrolide (50S)

196
Q

Clindamycin is a ______________

A

Lincosamide (50S)

197
Q

What is the spectrum of activity of macrolides?

A

generally broad spectrum but best against gram + aerobes
Good gram + aerobes: bacillus, coryne, E. rhusiopathiase, Listeria, Staphylocccic, Streptococci, Gram - aerobes

Moderate: enterococci, some Bordetella, Haemophilus, Legionella, Ehrlichia, Pasteurella

Resistant: Enterobacteriacease, Pseudomonas, Nocardia, Mycoplasma, Chlamydia, Mycobacteri,

198
Q

What are the three main mechanisms of resistance to Macrolides?

A

1) rRNA methylation- prevents binding to the ribosome
2) Active drug efflux-mediated by members of the ATP binding cassette family
3) Enzymatic inactivation- less common but due to esterase of phosphorylase inactivating enzymes

199
Q

T/F macrolides are widely distributed to all tissues of the body

A

F- all tissues except those of the CNS

200
Q

What macrolides are inhibitors of cytochrome p450

A

-Erythromycin and tiamulin

201
Q

What macrolides do not inhibit cytochrome p450

A

-Clarithromycin and azithromycin

202
Q

Clarithromycin is a ______

A

Macrolide (50S)

203
Q

azithromycin is a _______

A

Macrolide (50S)

204
Q

tiamulin

A

Macrolide (50S)

205
Q

Tylosin is a_________

A

Macrolide (50S)

206
Q

Macrolides adverse effects

A

*generally low, irritation, phlebitis
GI disturbance but can be life threatening in horses

207
Q

Erythromycin is horses can lead to__________

A

clostridium overgrowth and serious diarrheic illness/death

208
Q

Tilmicosin can result in___________ in species other than cattle and swine

A

cardiovascular toxicity

209
Q

What is the drug of choice for Campylobacter diarrhea or abortion

A

Erythromycin

210
Q

Macrolide clinical application

A

-Camplyobacter diarrhea/abortion (erythromycin)
-Penicilin-alternative to sensitive animals with gram + aerobes
-Ampicillin or Amoxicillin alternative in the treatment of leptospirosis
-Tetracycline alternative for rickettsial infection

211
Q

What classes have mycoplasma spp activity

A

-Tetracycline, Fluoroquinolones, Chloramphenicol, Some macrolides/lincosamidesLincos

212
Q

Tylosin

A

a macrolide used for treatment of local and systemic infections caused by mycoplasmas, gram + bacteria, anaerobes, and some respiratory gram - pathogens

213
Q

Tilmicosin

A

a macrolide that is used only in cattle (injected) and swine (medicated feed) for respiratory disease

214
Q

What is used in swine for the control/treatment of Brachyspira hyodysenteriae an mycoplasmal arthritis

A

Tiamulin (a macrolide)

215
Q

Clarithromycin

A

a macrolide that is the drug of choice for treating Rhodococcus equi when combined with Rifampin

216
Q

Tulathromycin

A

a long-acting, single-dose macrolide used for the treatment of respiratory disease in cattle and swine
accumulated in lung tissue
called Draxxin

217
Q

Pirlimycin is a ______

A

lincosamide

218
Q

Are Lincosamides bacteriostatic or bactericidal

A

both depending on the concentration, bacterial species and inoculum of bacteria

219
Q

What is the mechanism of action of lincosamides?

A

Bind to the 50S ribosomal subunit (same site as macrolides) and inhibit peptidyl transferase

220
Q

What are Lincosamides active against?

A

Gram + aerobes
mycoplasma
Anaerobes

221
Q

Lincosamides are widely distributed with excellent penetration of________

A

bone and soft tissues, including tendon sheaths
low levels in the CNS

222
Q

Lincosamide toxicities

A

Horses,Rabbits, hamsters, guinea pigs: necrotizing enterocolitis from toxigenic Clostridia

Salmonellosis in dogs

Neuromuscular blockage at high doses when given with anesthetics

223
Q

Why might you give Clindamycin?

A

use in dogs/cats for periodontal disease, osteomyelitis, dermatitis, and deep soft tissue infections caused by gram positive aerobes and anaerobes. also for toxiplasmosis

224
Q

Why might you give Lincomycin?

A

Ised in swine for swine dysentery, staphylococcal, streptococcal, and mycoplasmal infections

225
Q

Why might you give Pirlimycin

A

used for udder infusion produce for treatment of bovine mastitis caused by gram positive cocci

226
Q

What is mechanism of action of Sulfonamides?

A

inhibit dihydropteraste synthesase -inhibit the formation of pteroic acid - false substrate/competitive inhibitor
interfere with folic acid synthesis

227
Q

Are Sulfonamides bacteriostatic or bactericidal?

A

Bacteriostatic

228
Q

What is the spectrum of sulfonamides?

A

broad spectrum for bacteria and protozoa (Toxoplasma and coccidia)
best against gram + aerobes
moderate agaainst Staphyloccic, some gram - aerobes such as enterbacteriacea
Resistant: Mycobacterium, Mycoplasma

229
Q

T/F Sulfonamides have mycoplasma activity

A

F

230
Q

How are sulfonamides selective to killing microorganisms

A

animals take up preformed folic acid while bacteria synthesize folic acid
folic acid required for purine biosynthesis

231
Q

What two ways does sulfonamide resistance occur?

A

1) Production of insensitive dihydropteroate enzyme
2) Hyperproduction of PABA (antagonizes sulfonamide

232
Q

How are sulfonamides absorbed?

A

orally

233
Q

What antimicrobials form crystals in the urine in acidic environments

A

Sulfonamide crystals

234
Q

What are the toxicities from sulfonamides?

A

1) Urinary tract (Crystalluria, hematuria, leukopenia)
2) Hematopoetic disorders (Thrombocytopenia, anemia, leukopenia)
3) Dermatologic reactions (epidermal necrolysis)
4) KCS
5) Dogs- drug fever (doberman pinschers)- KCS, feverm arhtropathy, epistaxis

235
Q

What dog species should you avoid Sulfonamides in?

A

Doberman Pinschers

236
Q

Why do dogs experience longer half lifes and altered metabolites when given sulfonamides?

A

Because they are deficient in N-acetylation

237
Q

Priming dosing of sulfonamides

A

used when initiating sulfonamide treatment
administer maintenance doses that are half the priming dose at intervals that are equal to half life of drug

238
Q

Why should sulfonamides be only given IV

A

because of the alkalinity of parenteral formulations

239
Q

What is added synergistically to sulfonamides

A

diaminopyrimidines because they interfere with folic acid production through a different mechanism

240
Q

How does the mechanism of diaminopyrimidines differ from sulfonamides

A

Sulfonamides: Dihydropteroate synthetase

Diaminopyrimidine: Dihydrofolate reductase

241
Q

Are diaminopyrimidines bactericidal or bacteriostatic

A

Bacteriostatic

242
Q

How do you make Sulfonamides bactericidal?

A

Add a diaminopyrimidine like Trimethoprim

243
Q

What blocks dihydrofolate reductase

A

Diaminopyrimidines like trimethoprim

244
Q

Ormetoprime is a_______

A

Diaminopyrimidine

245
Q

Pyrimethamine is a ______-

A

Diaminopyrimidine

246
Q

Potentiated Sulfoamide spectrum of activity

A

good against aerobes (gram + or -)
some gram - anaerobes
resistant: rickettisa, leptospira, P. aerginosa, Mycoplasma

247
Q

Rifampin mechanism of action

A

inhibit RNA synthesis by binding of Beta subunit of DNA-dependent RNA polymerases
more active in gram + bacteria and mycobacterium

248
Q

HOw does Rifampin resistance occur

A

single mutation of B subunit of DNA dependent RNA polymerases

249
Q

What is treatment of choice for foals with Rhodococcus?

A

Rifampin

250
Q

Oxazolidinones mechanism of action

A

binds to 23S ribosomal RNA of the 50S subunit

251
Q

Oxazolidonones

A

antibiotic that binds to 50S subunit to block protein synthesis
high oral absorption
sparingly use - not routine

252
Q

Bacitracin

A

antibiotic that is a complex mixture of polypeptides that blocks phosophorylase reaction used topically and often combined with polymyxin B, neomycin or zinc

253
Q

Methenamine

A

antibiotic that is a urinary antiseptic used to treat UTIs. at acidic pH in urine breaks down to form formaldehyde and ammonia. Enhanced activity with acidity. Do not use with sulfonamides or crystals will form

254
Q

What effects the efficacy of a parasiticide?

A

1) Toxicity (dosage)
2) Ability to reach the parasite (Biology, timing, route of admin)

255
Q

What is good parasiticide practice?

A

correct use of compounds where application at recommended odsage
observation of residues and withholding times

256
Q

Why are withholding times critical for parasiticides?

A

for milk and meat animals intended for human consumption
-typically longer for bolus formulations
-Relative to other benzimidiazoles, thiabendazole is excreted rapidly

257
Q

Relative to other benzimidiazoles, what is excreted rapidly?

A

Thiabendazoles

258
Q

General mechanisms of parasiticides

A

1) Paralysis by stimulating or inhibiting neurotransmission (cholinergic agonist, GABA agonist, glutamate-gated Cl- channels)
2) Altered metabolic processes (inhibition of tubulin- helminths, inhibition of folic acid synthesis, inhibition of chiting fomration
3) Altered parasite repro (inhibition of protozoan replication

259
Q

What is the mechanism of action of Benzimidazoles?

A

impairment of microtubule polymerization (tubulin) , interference with microtubule-mediated transsport of secretory vesicles in parasite absorptive tissues
leads to impaired cell structure, integrity, or metabolism

260
Q

What is the mechanism of action of Tetrahydropyrimidines

A

causes paralysis of helminths through nicotinic cholinergic receptor agonist at the NMJ leading to sustained muscular contraction and tonic paralysis

261
Q

What is the mechanism of action of Macrocyclic lactones

A

causes paralysis of helminths by binding to glutamate-gated chloride channels in nematode and arthrpod nerve cells. Channels open, allowing influx. Paralysis to pharnyx, body wall, and uterine muscles of nematodes
Flaccid paralysis

262
Q

What does Benzimidazoles target?

A

Nematodes, Trematodes, +/- cesotdes

263
Q

What do macrocyclic lactones target

A

nematodes, ectoparasites

264
Q

T/F macrocyclic lactones need to be at high concentration to be effective

A

F- broad spectrum endectocides with activity at low levels

265
Q

Macrocyclic lactones

A

-Paralysis by binding glutamate-gated chloride channels (flaccid paralysis)
-Nematodes and ectoparasites
-Broad spectrum at low dosing levels
-Least toxic, highly effective (receptor sites not normally in CNS)
-From Streptomyces
May have activity against immature life stages
1)Avermectins (Ivermectin, Eprinmectin, Doramectin, Selamectin)
2) Milbemycin (Moxidectin and Milbeycin Oxime)
3) Spinosyns (Spinosad and Spinoteram)

266
Q

Avermectins like Ivermectin, Eprinomectin, Dorsmectin, and Selamectin are in what class of parasiticide?

A

Macrocyclic lactones

267
Q

Milbemycins like Moxidectin and Milbemycin Oxime are in what class of parasiticide?

A

Macrocyclic lactones

268
Q

Spinosyns like Spinosad and Spinoteram are in what class of macrocyclic lactones?

A

Macrocyclic lactones

269
Q

Advantage Multi, Heartgard, and Cydectin are products that are

A

Macrocyclic lactones

270
Q

What parasites are targeted by macrocyclic lactones?

A

nematodes and ectoparasites

271
Q

Benzimidazoles

A

impairement of microtubulin (tubilin)
first class of modern anthelmintics
borad spectrum of activity, particularly against nematodes
usually given orally as paste, suspension, bolus
wide margin of safety, rapid elimination

272
Q

What group of parasiticides end in-azoles

A

Benzimidazoles

273
Q

Albendazole, Oxibendazole, Fenbendazole, Oxfendazole, Mebendazole, Thiabendazole, and Febentel is in what group of parasiticides

A

Benzimidazoles

274
Q

What do Benzimidiazoles target

A

Nematodes
Trematodes
+/- cestodes

275
Q

Triclabendazole is a benzimiadazole that has effect on trematodes but no effective on _________

A

nematodes

276
Q

What do you give for treating Fasciola hepatica infection

A

Clorsulon (a Benzene Sulfonamide)

277
Q

What parasites do Benzene Sulfonamides target

A

Tapeworms
Trematodes

278
Q

What time frame are flukes susceptible to Benzene Sulfonamides?

A

2-3 months after infection
more difficult to treat later as they are walled off by connective tissues

279
Q

What is the mechanism of action of Benzene Sulfonamides?

A

inhibit enzymes in glycolytic pathway of cestodes and trematodes

280
Q

Tetrahydropyrimidines

A

Pyrantel salts - GI Nematodes
cause paralysis through nicotinic receptor agonist at the NMJ and sustained muscular contraction and tonic paralysis
high degree of safety, some may be teratogenic
Pyrantel pamoate (horse, cat, dog)
Pyrantel tartate (horse)
Morantel (Cows, goats)
should be kept out of direct sunlight
PO administration

281
Q

Pyrantel tartrate, Pyrantel pamoate, and Morantel are examples of _______

A

Tetrahydropyrimidines “Pyrantel Salts”

282
Q

Prazinoisoquinolones mechanism of action

A

not well understood but tegumental damage and paralytic muscular contraction of cesotdes leads to rapid death and explusion
reduced uptake of glucose, depletion of energy reserves

283
Q

What species does Prazinoisoquinolones target

A

Cestodes and trematodes

284
Q

Epsiprantel and Praziquentel are examples of

A

Prazinosioquinolones

285
Q

Prazinoisoquinolones

A

targets cestodes and trematodes
Epsiprantel (Taenia, Dipylidium caninum) and Praziquantel (Taenia, Dipylidium caninum, Echinococcus in small animals- if oral can do Moniezia, Anoplocephala perfoliata and poutry)

286
Q

Arsenicals

A

parasiticides that are hepato and nephrotoxic (monitor during therapy)
rapidly absorbed after intramuscular injection
ex: Melarsomine dihydrochloride
MOA not well understood

287
Q

What is an advantage of Praziquantel or Epsiprantel

A

In addition to targeting Taenia and Dipylidium caninum, it has additonal activity againast echinococcus

288
Q

What drug inhibits fungal mitosis?

A

Griseofulvin

289
Q

What drug inhibits fungal RNA and protein synthesis

A

5-Flucytosine

290
Q

What drug inhibits fungal protein synthesis?

A

Sardarin and 5-flucytosine

291
Q

Cell membrane active antifungals target___________

A

ergosterol

292
Q

Terbinafine

A

an allylamine (inhibits synthesis of ergosterol, the cell membrane of fungus, via inhibiting squalene epoxidase)
Broad spectrum and effective against dermatophytes, yeasts, Aspergillus, and dimorphic fungi
Fungicidal- kills fungus
Oral and topical
inhibitor of some CYP450 enymes

293
Q

What is the mechanism of action of Terbinafine

A

an allylamine: inhibition of squalene epoxidase (blocks formation of ergosterol)

294
Q

Is Terbinafine fungicidal or fungistatic?

A

fungicidal

295
Q

Naftifine

A

an allylamine: inhibition of squalene epoxidase blocking the formation of ergosterol
broad spectrum, effective against dermatophytes, yeasts, Aspergillus, dimorphic fungi

296
Q

What increases the clearance of Terbinafine?

A

Rifampin (Terbinafine is an inhibitor of some CYP450 enzymes)

297
Q

Amphotericin B

A

A polyene: Fungicidal by binding to ergosterol, causing cell leakage and cell death
primarily for systemic fungal treatments, broad spectrum
Resistance develops slowlu
Binding to mammalian cell cholesterol makes it the most toxic of the clinically used antifungals in vet med

298
Q

What two drugs are allylamine and inhibit squalene epoxidase- blocking the formation of ergosterol?

A

Terbinafine and Naftifine

299
Q

What is the most toxic of the clinically used antifungals in vet med and why?

A

Amphotericin B because of binding to the mammalian cell cholesterol

300
Q

What is the only FDA approved anti-fungal for ophthalmic use?

A

Natamycin (a polyene)

301
Q

what is the mechanism of action of polyenes like Amphotericin B, Nystatin, and natamycin (pimaricin)?

A

fungicidal by binding to ergosterol, causing cell leakage and cell death

302
Q

How do you administer Amphotericin B?

A

not well absorbed from the GI tract
administered IV- binds to cell mebranes and lipoproteins
Slowly distributed to most tissues except those of the CNS, eyes, and bone. accumulates in the liver, kidneys and lungs

lipid formulations are taken up by mononuclear phagocytes (and transported to the sites of infection) with lower renal concentrations, longer half life and less nephrotoxicity

303
Q

What is used synergistically with Amphotericin B to decrease toxicity

A

Flucytosine

304
Q

What is a serious side effect of Amphotericin B

A

Nephrotoxicity: Renal vasoconstriction, decreased glomerular filtration, and damage to the tubular epithelium

Must monitor weekly during therapy

lose concentrating ability, hypokalemia, hypomagnesemia, and red / white blood cells, albumin, and tubular casts appearing in the urine

305
Q

What formulations of Amphotericin B have lower accumulation in the kidneys and reduced nephrotoxicity

A

liposomal or lipid-complexed formulations
because they are taken up into mononuclear phagocytic cells

306
Q

What 3 drugs are polyenes and therefore are fungicidal by binding to ergosterol?

A

1) Amphotericin B
2) Nystatin
3) Natamycin (pimaricin)

307
Q

What is the mechanism of action of Antifungal -azoles (Imidazole and Triazole)?

A

they target fungal cytochrome P450-Cyp51p by binding to lanosterol 14a-demthylase to inhibit ergosterol synthesis. Structural differences in azoles dictate the binding site on the CYP system: antifungal potency, spectrum of activity, bioavailability, drug interactions, and toxic potential

308
Q

Are antifungal -azoles fungistatic or fungicidal?

A

Fungistatic

309
Q

Do Imidazoles or Triazoles have a greater adverse effects

A

Imidazoles- endocrine adverse effects through cholesterol inhibition
Triazoles have less effect on mammalian P450

310
Q

Miconazole, Clotimazole, Ketoconazole, itraconazole, fuconazole, and voriconazole are all:

A

Triazoles and Imidazoles that are fungistatic by inhibiting ergosterol synthesis

311
Q

Whay are the uses of triazole and imidazoles?

A

broad antifungal spectrum of activity for systemic mycoses, yeats, and dermatophytes
Very limited resistance

312
Q

What antifungal -azoles penetrate the CNS very well?

A

Fluconazole and Voriconazole

313
Q

What antifungal -azole would you use for fungal cystitis because it is excreted in urine as an active drug ?

A

Fluconazole

314
Q

Fluconazole

A

A triazole that is fungistatic by inhibiting ergosterol synthesis. has less effect on mammalian p450s than imidazoles
readily absorbed orally
only -azole that is excreted in urine as an active drug an is useful for fungal cystitis

315
Q

What are the worries with giving Ketoconazole?

A

Azoles may be inhibitor or substrate of CYP system
1) inhibit which leads to accumulation of other co-administered drugs, hepatic dysfuncton, anorexia, vomiting, diarrhea
2) Suppression of adrenal or gonadal steroids (testosterone). may cause fetal death causing abortion/stillbirths
3) Reversible lightening of haircoat coloration and alopecia
4) Hepatotoxicity in cats is a risk

316
Q

Is Fluconazole or Ketoconazole better tolerated?

A

Fluconazole

317
Q

What considerations should you make when giving -azoles to pregnant animals?

A

Just. dont give them, avoid all systemic use

318
Q

Is itraconazole or ketoconazole better in cats?

A

itraconazole

319
Q

How is Ketoconazole administered?

A

orally to treat systemic mycotic infections (controlling coccidioidomycosis, blastomycosis, histoplasmosis) and dermatophytosis

320
Q

What is the treatment of chouce for cryptococcosis and some disseminated mycoses such as coccidioidal meningitis)

A

Fluconazole

321
Q

What has the broadest spectrum of activity of all the -azoles?

A

Voriconazole
also has increased activity against aspergillosis

322
Q

Griseofulvin

A

Fungistatic: inhibits mitosis (slow action)
Effective only as systemic agent against dermatophytes
Resistance is rare
distributes to keratin precursor cells
Metabolized by liver
Cats more susceptible to toxic effects (Leukopenia+anemia in kittens, teratogenic, altered spermatogenesis)

323
Q

What antifungal is only used systemically against dermatophytes

A

Griseofulvin

324
Q

What is Griseofulvin’s mechanism of action

A

inhibits mitosis of fungus (fungistatic)

325
Q

Is Griseofulvin fungistatic or fungicidal?

A

Fungistatic

326
Q

Where does Griseofulvin distribute to?

A

Keratin precursor cells

327
Q

What are concerns with Griseofulvin?

A

1) Leukopenia and anemia in kittens with high doses
2) Do not give in animals with impaired liver function
3) Contraindicated in pregnant animals because it is teratogenic
4) Altered spermatogenesis

328
Q

What 3 types patients should you not give Griseofulvin to?

A

Impaired hepatic function
Pregnant
Food producing animals

329
Q

How should you treat Candida infections?

A

Amphotericin B or Fluconazole

Alternative Itraconazole

330
Q

Why are all antiviral drugs virustatic?

A

because they must inhibit viral replication without destroying the host cells

331
Q

Pharmacokinetic requirements of antiviral drugs must include what two things

A

Intracellular and nuclear penetration

332
Q

Do antiviral drugs tend to have a narrow or wide spectrum of activity?

A

Narrow

333
Q

How do antiviral protease inhibitors work

A

they block the activity of viral proteases that function in the assembly of viral components into a viron before release from the host cell

334
Q

Amantadine and Rimantadine

A

act on early step of viral replication after the attachment of the virus to cell receptors
Inhibits replication of influenza A and C virus, Sendai virus , absorbed from GI tract
Few side effects, most are CNS
Block the uncoating of the virus

335
Q

What are the main uses of Amantadine and Rimantadine

A

inhibiting the replication of influenza A and C virus
*Block uncoating of the virus (antimembrane drugs)

336
Q

Idoxuridine (IDU)

A

a nucleoside analog, inhibit viral DNA/RNA synthesis, that is effective for the treatment of herpesvirus infection of the superficial layers of the cornea (herpesvirus keratitis) and of the skin, but is toxic when administered systemically

337
Q

How should you treat herpesvirus keratitis

A

Idoxuridine (IDU), do not use systemically

or Trifluridine

338
Q

Acyclovir

A

an antiviral that is phosphorylated by virus-induced thymidine kinase, better substrate and inhibitor of viral rather than cellular DNA polymerase
Relatively safe good for herpesvirus
ophthalmic ointment, topical ointment and cream, IV preparation, various oral formulation

339
Q

Ribavirin

A

a synthetic triazole nucleoside (guanosine analog) with a broad spectrum of activity against many RNA and DNA viruses, both in vitro and in vivo.
-inhibit viral associated enzymes, capping of viral mRNA, and inhibition of viral polypeptide synthesis
Well absorbed
Narro margin of safety in domestic animals
admin by topical, parenteral, oral, and aerosol routes

340
Q

What is the mechanism of Ribavirin

A

-inhibit viral associated enzymes, capping of viral mRNA, and inhibition of viral polypeptide synthesis

341
Q

Interferons mechanism of action

A

activation of cellular endonucleases that degrade viral mRNA
also modulate the immune system of the host
inhibit the replication of a wide variety of viruses
not yet been found to be clinically useful because of their toxicity

342
Q

What do neuraminidase inhibitors do

A

they enzymatically cleave sialic acid residues which is required to release newly formed virus particles from infected cells. ultimately blocking the virus
effective against influenza A and B

343
Q

What are neuraminidase inhibitors active against?

A

influenza A and B

344
Q

Zanamivir and Oseltamivir are examples of

A

neuraminidase inhibitors (an enzyme that cleaves sialic acid residues)
useful for the treatment of influenza A and B

345
Q

Zanamivir

A

Relenza
A neuraminidase inhibitors that is active against both influenza A and B
topical treatment
Reduce period of flu symptoms by 1 day. Improved flu symptoms within 2 days

346
Q

Oseltamivir

A

Tamiflu
A neuraminidase inhibitors that is active against both influenza A and B
Reduces severity of flu symptoms by 40% and also reduces rates of secondary complications
reduced infection of patients contacts by approximately 89%

347
Q

Name the two neuraminidase inhibitors

A

Zanamivir (Relenza)
Oseltamivir (Tamiflu)

348
Q

What does Lysine (Enisyl-F) reduce the frequency and severity of?

A

FHV-1

349
Q

How does Lysine reduce the frequency and severity of FHV-1

A

Herpes virus requires arginine and lysine may interfere with the absorption of arginine in the intestine via a high lysine/arginine ratio in the diet

350
Q

What in the diet can interfere with the absorption of arginine, which herpesvirus requires?

A

Lysine

351
Q

What is the major non-psychoactive Cannabinoid?

A

Cannabidiol (CDB)

352
Q

What is the major psychoactive Cannabinoid

A

THC (-delta nine-tetrahydrocannabinol)

353
Q

What Schedule drug is marijuana?

A

Schedule I controlled drug
“No currently accepted medical use and high potential for abuse” - DEA

354
Q

CB1 and CB2 receptors are what types of receptors?

A

G protein-couple receptors

355
Q

Endocannabinoid system

A

a system that has autocrine and paracrine activity

neurotransmitors that are agonists on CB1 receptors (anandamide) and CB2 receptors (2-arachidonoylglycerol)

synthesized from mebrane lipids
not stored in pools (e.g vesicles)
locally produced, local action
can be classified as autacoids
much less potent

356
Q

What receptor of the endocannabinoid system has effects on cognition

A

CB1

357
Q

CB1 receptors

A

CNS

presynaptic G protein coupled receptor

glutamatergic and GABAergic neurons
activation=decrease in neurotransmitter release

358
Q

What receptor of the endocannabinoid system has effects on peripheral immune cells

A

CB2

359
Q

What endocannabinoid receptor decreases cAMP and increases MAPK on peripheral immune cells when activated ?

A

CB2

360
Q

What receptor of the endocannabinoid receptor decreases neurotranmission release when activated?

A

CB1

361
Q

Where are CB1 receptors located

A

mostly in the nervous system and brain

362
Q

What effects do CB2 receptors have?

A

-inflammation and chronic pain
-inhibits pro-inflammatory cytokine production
-immunomodulation (immunosuppression)
*theapeutic cannabinooid receptor

363
Q

T/F THC has high affinity for both CB1 and CB2 receptors

A

T, CB1 effect more than CB2 but high for both generally

364
Q

T/F CBD has a low affinity for CB1 and CB2 receptors

A

T, but can act synergistically with THC to modulate pain through pathways

365
Q

T/F CBD has no anti-inflammatory effects

A

F

366
Q

What are the potential therapeutic uses of CBD

A

1) Anti-emesis (if unresponsive to 5-HT3 agonists like ondansetron)
2) Diabetes mellitus- reduces pancreatic inflammation and via antioxidant effects
3) Cancer- reduce neoplastic proliferation in select tumor cell lines
4) Antibacterial?
5) Pain, inflammation, and immunomodulation- acute/chronic pain, decrease Tcell activity, arhtritis and psoriasis
6) Epilepsy- anti-epileptic effects
7) anxiolytic- exerts benzodiazepam-independent anxiolytic activity by modulating 5-HT1a receptors possibly

367
Q

T/F CBD products are regulated

A

F

368
Q

What cannabinoid receptor dominates toxicity?

A

CB1

369
Q

Signs of Cannabinoid toxicity in dogs

A

1) Ataxia, incoordination
2) Depression, disorientation
3) Mydriasis
4) Hypothermia
5) hypersalivation
6) Bradycardia

370
Q

Static ataxia

A

associated with THC toxicity- loss of ability to maintain fixed position due to binding of CB1 agonist in cerebellum affecting movement control

371
Q

How to treat cannabinoid toxicity

A

no specific antiote
supportive measures (sedatives, antiemtics, IV fluids as neccessary
Activated charcoal may reduce half life

372
Q

What systems can trigger emesis

A

1) CNS input (gross, smells, thoughts)
2) Vestibular apparatus (motion sickness, vestibular disease, inner ear infections)
3) CRTZ- chemo receptor trigger zone (drugs, toxins, pH, metabolites)
4) GI tract signals (inflammation, irritation, stimulation, constipation)

373
Q

What can Apomorphine be used for

A

drops in conjunctiva or IV to induce emesis
IV- give it in back leg because it works really quickly

373
Q

What is Apomorphine’s mechanism of action

A

dopaminergic receptor agonist (D2) to trigger the chemoreceptor trigger zone for emesis

374
Q

How can you give apomorphine

A

in the conjunctiva or IV (back leg)

375
Q

Why should you not use apomorphine in cats?

A

cats do not dopaminergic receptors in their chemoreceptor trigger zone but have them elsewhere so they will not induce emesis

376
Q

T/F Apomorphine is used to induce emesis in cats

A

F- they do not have dopaminergic receptors in their CRTZ

377
Q

Ropinirole (Clevor)

A

eye drops used to induce emesis in dogs

378
Q

What can Ropinirole be used for?

A

Inducing emesis via eye drop

379
Q

Anti-Emetics do:

A

Antagonist for receptors in the chemoreceptor trigger zone

380
Q

What stimulates NK1 receptors for emesis?

A

Substance P

381
Q

Maropitant (CWhaerenia) mechanism of action

A

It is an NK1 receptor antagonist and prevents emesis

382
Q

What is Cerenia’s name

A

Maropitant

383
Q

Why is Maropitant so effective at preventing emesis

A

There are NK1 receptors in the chemoreceptor trigger zone and the gastrointestinal tract so it able to antagonize both

384
Q

What drug is a neurokinin-1 receptor antagonist

A

Maropitant (Cerenia)

385
Q

Maropitant is well tolerated in dogs and cats, but in both species it may cause ___________ during injection

A

pain/vocalization

386
Q

Ondansetron (Zofran) is a __________ receptor __________

A

Ondansetron (Zofran) is a 5-HT receptor antagonist

387
Q

Ondansetron is well tolerated in dogs and cats but adverse effects may include __________

A

1) Constipation
2) Sleepiness
3) Head-shaking

388
Q

What does the parietal cell do

A

Secrete HCl into the stomach via a protein pump under the H2 receptor

389
Q

What 2 drugs can you use to reduce gastric acid secretion?

A

1) Famotidine (H2 receptor antagonist)
2) Omeprazole (proton pump inhibitor)

390
Q

What drug is an H2 receptor antagonist, resulting in reduced gastric acid secretion

A

Famotidine

391
Q

What drug inhibits proton pumps in the stomach, resulting in reduce gastric acid secretion?

A

Omeprazole

392
Q

Is omeprazole famotidine better at raising gastric pH

A

Omeprazole (proton pump inhibitor)

393
Q

What are some adverse gi effects of dogs receiving oral omeprazole

A

1) Reduced fecal quality 9more liquid)

394
Q

Is omeprazole dosed once or twice daily for best efficacy

A

twice

395
Q

What is the most efficacious way to administer omeprazole

A

reformulated paste (RP)

396
Q

What are some ways to get cats to eat?

A

1) try canned food
2) Warm it up
3) Soak kibble in tuna juice
4) Bowls that dont hurt whiskers?
5) acupuncture
Drugs:
Cyproheptadine
or
Mirtazapine
or Gabapentin

397
Q

What is the mechanism of action of Cyproheptadine

A

antihistamine (serotonin antagonist) that has a side effect of stimulating appetite

398
Q

Is Cyproheptadine really used anymore in vet med for appetite stimulation?

A

nah. Mirtazapine is pretty og

399
Q

What is Mirtazapine used for

A

appetite stimulant (side effect)
anti-anxiety, antidepressant
imrproves rats sexual motivation test
-Anti-emetic (anti-nausea) 5-HT3 antagonist

400
Q

What is the mechanism of action of Mirtazapine

A

5-HT3 antagonist (anti-emetic)
good for appetite stimulation

401
Q

T/F you can give Cyproheptadine with Mirtazapine for appetite stimulation synergy

A

F- don’t give together
one is antidote for the overdose of the other

402
Q

Mirataz is a ________

A

transdermal form of mirtazapine that is used for appetite stimulation is kitty cats

403
Q

What is the result of oral diazepam as use for appetite stimulation is cats

A

Fulminant hepatic failure
DO NOT USE ORAL DIAZEPAM
Okay to give IV diazepam though

404
Q

Ghrelin

A

a hormone that is secreted to tell you to eat. elevated when hungry

405
Q

Leptin

A

a satiety hormone that tells you are full.
hormone made by adipose
elevated when full

406
Q

Mirtazapine (Entyce)

A

A ghrelin receptor agonist that stimulates the hypothalamus to increase hunger
Stimulates the pituitary gland

407
Q

Capromorelin

A

orally active ghrelin agonist that caused sustained increases in IGF-1, increased food intake and body weight in cats

408
Q

Gabapentin

A

used to calm down stressed cats before the vet
side effect: increased in appetite and good at stimulating appetite

409
Q

What is the route of choice for ondansetron

A

IV- poor oral bioavailability

410
Q

Loperamid (imodium)

A

binds u opioid receptors in the myenteric plexus of the large intestine
decreases the activity of the myenteric plexus, decreasing longitudinal and circular intestinal smooth muscle

411
Q

What is the side effect of opioid induced constipation, like from Loperamide (Imodium)

A

Constipation

412
Q

What is Loperamide’s (Imodium) mechanism of action

A

binds u-opioid receptors in the myenteric plexus of the large intestine to decrease longitudinal and circular intestinal smooth muscle

413
Q

What are the two major types of small intestine motility

A

1) peristalsis (propulsion)
2) Segmentation (mixing)

414
Q

What mimics the motilin component on muscarinic receptor for GI motility

A

Erythromycin

415
Q

What mimics the role of Serotonin on 5-HT4 receptors for gut motility

A

Cisapride

416
Q

What 3 things can increase GI motility by increase ACh release at the cholinergic motor neuron?

A

1) Serotonin (5-HT4) -mimic by Cisapride
2) Motilin (hormone) - mimic by erythromycin
3) Dopamin antagonist (Metoclopramide)

417
Q

Metoclopramide

A

increase GI motility (via dopamine antagonist) via increase tone of GI contrations, relaxed pyloric sphincter, increases duodenal/jejunal peristalsis
decreased time to empty stomach/GI transit time
increase LES P and reduce gastresophageal reflux
-only on the small intestine

little to no effect on the colonic motility

418
Q

Where in the intestine does Metoclopramide act to increase GI tract movement

A

only small intestine and constant rate of infusion
little to no effect on colonic motilty so rarely used

419
Q

Metoclopramide mechanism of action

A

Dopamine antagonist leading to increase ACh release onto GI smooth muscle
this enhances GI motility but only in the small intestine

420
Q

Cisapride mechanism of action

A

Serotonin (5-HT4) agonist to increase release of ACh onto GI smooth muscle
happens in colon and small intestine

421
Q

What is the drug of choice for moving a cat’s colon

A

Cisapride is the drug of choice for moving a cat’s colon

422
Q

How do you treat inflammatory bowel disease

A

reduce the antigenic stimulation and resulting inflammation
1) Hypoallergenic/hydrolyzed diet
2) Prednisolone

423
Q

If a cat has a problematic liver, what glucocorticoid should you give to treat IBD?

A

Prednisolone (not prednisone) because it is the active compound, skipping the need for conversion by the liver

424
Q

What do you get at higher doses of glucocorticoids

A

Immunosuppression (Anti-inflammatory at lower doses)

425
Q

Budesonide

A

a glucocorticoid that predominately acts on GI tract and gets inactivated before reaching other parts of the body
via first pass hepatic metabolism
decreases systemic steroid effects
no better than prednisone for clinical response to IBD

426
Q

What is a glucocorticoid that predominately only acts on the GI tract

A

Budesonide

427
Q

Cobalamin absorption

A

Vitamin B12
enters into stomach
separated from food stuffs
attached to R protein
joins with intrinsic factor (produced by pancreas)
transports cobalamin to distal small intestine where transcobalamin can move it into the bloodstream

428
Q

What is needed for the absorption of vitamin B12/Cobalamin

A

intrinsic factor from the pancreas

429
Q

How do you treat chronic copper hepatopathy in dogs

A

Penicillamine to absorb and bind copper

430
Q

how do you treat acute neutrophilic cholangitis in cats

A

Clavamox, antibiotic

431
Q

One way should you treat vomiting in a dog

A

Cerenia (maropitant)

432
Q

One way you should treat nausea in a cat

A

Omeprazole (proton pump inhibitor)

433
Q

one way you should increase appetite in cats

A

Mirtazapine (synthetic ghrelin)

434
Q
A

Pharm (4 decks)

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