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PHARMACOLOGY > Unit 3 - Antimicrobials > Flashcards

Unit 3 - Antimicrobials Flashcards

1
Q

What are antimicrobials?

A

Compounds used to kill or inhibit microbial growth

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2
Q

What types of antimicrobials are there and what defines them/

A

Target organism or Spectrum of activity - bacteria, fungi, virus, protozoan
-static (inhibition of replication but does not directly kill) - bacteriostat, fungistat, virustat, protozoistat
-Cidal (kills) - bacteriocide, fungicide, virucide, protozoicide

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3
Q

What is antimicrobial therapy? What are some factors involved in choosing an appropriate drug?

A

Goal is to kill or inhib specific pathogens while not harming the host
Factors involve susceptible microorganism (determined based on culture and sensitivity)
Access the site of infection at appropriate concentrations
Host tolerance to the drug

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4
Q

What is microbial susceptibility?

A

Based on minimum inhibitory concentration
it is strain and antimicrobial specific
Compare maximum tolerated dose (MTD) to MIC.
Compare drugs therapeutic range with its MIC classifies a pathogen as sensitive or resistant to that drug

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5
Q

Is a microbe resistant, or sensitive if MIC>MTD, what about MIC<MTD

A

IF MIC greater than MTD = resistant
IF MIC less than MTD = sensitive

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6
Q

What two princibles dictate whether a microbial works?

A

Concentration-dependence: based on peak serum concentration maintained above MIC
and Time-dependence: based on amount of time drug stays above the minimum inhibitory concentration (MIC)

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7
Q

What is antimicrobial resistance?

A

capability of an organism to survive in the presence of antimicrobials and passes it on to other microbes via chromosomes (vertical transmission) and plasmids (horizontal transmission)
May result from random genetic mutations or the inappropriate use of antimicrobials
Causes selection pressure which results in large resistant populations

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8
Q

Why is antibiotic resistance important?

A

Risk of resistance inc when antibiotics are used inappropriately bc anytime bact is exposed to an ABC and not killed (broad spectrum, bacteriostatic, under-dosing below MIC)
Unnecessary prescription - metaphylaxis/prophylaxis, viral infections (not all bugs need drugs)
Poor owner compliance
Unnecessary exposure - exposure thru residues, failures to follow WDTs

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9
Q

What are drug residues?

A

when a food-animal is treated with a medication, food products (meat, milk, eggs) must not contain drug residues from treatment
Residues are unacceptable bc of human hypersensitivities and proliferation of resistant microbial populations

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10
Q

How can drug residues be avoided?

A

ensure WDT for drugs are adhered to
Label all dispensed medications with clear instructions for proper administration and include WDTs

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11
Q

What is antimicrobial stewartship?

A

some antibiotics should be “off limits” - save the big guns for the big bugs. ex MRSA (methicillin resistance staph. aureus)
this includes prescription feed additives
ideally treat based on culture and sensitivity

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12
Q

What are the 5 basic mechanisms of antibiotic action against bacteria cells?

A
  1. inhibition of cell wall synthesis (most common)
  2. inhibition of protein synthesis (translation) 2nd largest class
  3. Alteration of cell membranes
  4. Inhibition of nucleic acid synthesis
  5. Antimetabolite activity
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13
Q

How does inhibiting the cell wall synthesis work?

A

baterial protoplasm draws water into the bacterium by osmosis, the bacterial cell wall keeps the bacterium from bursting.
these drugs are most effective against actively dividing bacteria

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14
Q

How dows inhibiting protein synthesis thru translation work?

A

Disruption of protein synthesis by combining with ribosome and interfering with mRNA or tRNA
blocks cell from dividing and results in cell death
can also cause damage to cell membrane

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15
Q

How can altering bacteria cell membranes help the mechanism of action antibiotics?

A

these drugs make the cell membrane “leaky”
drug molecules are more readily enter the cell
cytoplasmic components are more readily able to escape the cell

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16
Q

How does inhibiting nucleic acid synthesis work in favor of antibiotics?

A

interfere with the replication and transcription of DNA in bacterial cells
these drugs are less preferred because they may also interfere with human DNA replication and transcription

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17
Q

What do newer antibiotics have in regards to inhibiting nucleic acid synthesis?

A

They disrupt the DNA function by interfering with the enzymes needed for DNA to function or replicate, rather than the replication itself
attack specific types of structures only found in bacteria and not mammalian cells

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18
Q

What is antimetabolite activity?

A

antibiotics that mimic the structure of certain substrates in such a way that the normal substrate is replaced so the enzyme does not work as it should
in the process, needed metabolites are not created jeopardizing the well being of the bacteria

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19
Q

What does the ideal antibiotic protocol include

A
  1. organism identified and susceptible to drug chosen
  2. Drug is bacteriocidal and narrow spectrum (bateriostatic drug, patient must have a functioning immune system)
  3. Good distribution to the site of infection
  4. High TI; few side effects; patient must be able to tolerate the tx
  5. no ability to acquire resistance
  6. dosing regiment easy to follow
  7. patient returns for follow-up to ensure therapeutic goal reached
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20
Q

What are 3 goals when using antibiotics

A
  1. resolution of bacterial infection
  2. no or acceptable side effects
  3. no resistance
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21
Q

What are 1st line antibiotics?

A

the go to antibiotics
3 characteristics
1. bacteriocidal, lower rist of causing resistance when used correctly
2. narrow-spectrum - older drugs only work on gram+, newer broad spect have some gram - activity
3. least side effects - bc animal cells do not have cell walls
1 and 2 make them less likely to cause resistance

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22
Q

What are unique about beta-lactams
a

A

all have beta-lactam rings
only human products available
1st line antibiotics - cidal, narrow spectrum, less S/E
Resistance is often bc of beta-lactamase destruction of pharmaceutically active beta-lactam ring
bact that are resistant to penicillins are usually resistant to the cephalosporins and vice-versa
patients with penicillin allergies also have allergies to other beta-lactams

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23
Q

What do penecillins mostly kill?

A

Gram+ bact
drug will bind to bact enzyme responsible for cross-linking the peptidoglycan layers that make up the cell wall
Prevents stabilization of the cell wall; bact die from water entering the cell
only works on actively dividing bact

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24
Q

What are some properties of penicillins?

A

hydrophilic - well absorbed from injection sites w/ excellent volume of distribution, drawn to inflamed tissues; can penetrate abscesses
Not metabolized in river
eliminated in active form in kidneys; also found in active form in secretions (milk)

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25
Q

What are some precautions when with penicillin?

A

when given PO, may destroy Gram+ bact residing in lumen of int. tract, allowing more pathogenic bact to proliferate (yogurt, pre/probiotics to counteract this)
Adverse reactions to penicillins are rare, but can include Type 1 hypersensitivity reactions
Must observe WDT in food animals - label all dispensed meds w/ clear instructions for proper admin and WDT

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26
Q

What is penicillin resistance?

A

Via plasmids that contain the gene for beta-lactamase enzyme (beta-lactamase cuts the beta-lactam ring so drug is no longer active)
This plasmid can be shared w/ other bact and is passed to progeny > spread of resistance
Enzyme inactivates any drug containing the beta-lactam ring (penicillins, cephalosporins, carbopenams

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27
Q

What are the different penicillin classes?

A

Naturally occuring penicillins
Aminopenicillins (broad spectrum)
Beta-lactamase resistant penicillins (penicillinase resistant)
Extended-spectrum penicillins
potentiated penicillins (resistant to the B-lactamase enzyme)

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28
Q

What is penicillin G?

A

Very narrow spectrum (gram- only)
Common use in LA - formulations NOT interchangeable but various injectable formulations, diff pharmacokinetics = diff duration of effects, diff WDT
Na/K Pen G (aqueous) IV or IM use (most common, shortest action 1hr; 3d WDT)
Procaine PenG suspension (IM only, NEVER Iv bc of heartblock. 24 hr, reaction in horses, will test pos at shows)
Benzathine peng (suspension), slow release formulation, 5d, 28 WDT

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29
Q

What is unique about aminopenicillins?

A

Broadspectrum penicillins
gram + and a limited # of gram-
binds to surface of gram- cell wall and prevents bact from adhering to surfaces and one another (prevents colonizing)
common in SA
Ampicillin and Amoxicillin - injectable and oral form

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30
Q

What are unique about extended-spectrum penicillins?

A

drugs held in reserve, used to treat severe, resistant gram- infections
activity against Pseudomonas and other gram- bact (better able to penetrate outer cell wall compared to other penicillins)
synergistic when admind with aminoglycosides and have good activity against anaerobes
Ex. ticarcillin, piperacillin, carbenicillin

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31
Q

WHat are potentiated penicillins?

A

amoxicillin/clavulanic acid (amoxi-clav)
amoxicillin which has been combined with a second drug, clavulanic acid
Clav acid protect the penicillin from bact b-lactamase enzymes
Clavamox, norovlac, clavaseptin

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32
Q

What are some side effects of penicillins?

A

fairly safe bc animal cells do not have cell walls so side effects are related to disturbance of normal flora, formulations and allergies
1. GI issues
2. Rapid injection IV can cause neurological signs or anaphylaxis or sudden death
3. Allergies/anaphylaxis in animals and people can be very severe

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33
Q

How do GI issues present as side effects from penicillins?

A

most common, only if given orally, vomit/diarrhea/inappetance
chemical irritation or disturbs normal flora
will dec if given food; but, with giving food dec absorption (may need to adjust dose or give 1h after feeding

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34
Q

How might rapid injection IV of penicillions present for side effects?

A

can cause neurological signs or anaphylaxis or sudden death
anytime given IV, give slow injection (1 dose over 10/20 min)
procain PenG NEVER IV, IM only bc giving IV causes acute excitement and death due to local anesthetic OD
can occur when given IM if small amount enters a vessel
Ex. horses become hyperalert, spooked, may collapse, last 2-5 mins

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35
Q

With penicillin side effects, how might allergies/anaphylaxis present?

A

Can be very severe
of all the beta-lactams, occurs most commonly with penicillins - PenG naturally derived from the Penicillium fungus and has highest risk of allergy
Some anims/peopls w/ penicillin allergies may react to cephalosporins/carbapenems
more likely if injected
Hives, throat swlls, vomit, diarrhea, hepatitis, pruritus, vasodilation
WDT in food animals, watch it

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36
Q

What are characteristics of cephalosporins?

A

contains the beta-lactam ring
blocks cell wall synthesis
gram+ bact
susceptible to beta-lactamase resistance (same plasmid-driven mechanism as for penicillins)
concentration- dependant
very commonly used
names begin with ceph or cef

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37
Q

What happens with the 1st gen of cephalosproins?

A

1st, oldest, gram+ only
cephalexin - common PO
Cefazolin (surgical prophylaxis, slow IV over 20 min)

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38
Q

What cephalosporins are cluded with the 3rd gen?

A

Cefovecin, cefpodoxime, ceftiofur(Ex, excede - 2 tx 5 days apart)
newer gens broader spectum (also get gram- and anaerobes) have better tissue distribution

39
Q

What is convenia?

A

Cephalosproin, contains cefovecin (3rd gen), long acting
14d in therapeutic range after single SQ injection
Indicated for cats difficult to pill, off label UTI, soft tissue abscesses
Has been over-used due to convenience; seeing inc resistance. recommend susceptibility testing b4 use -always indicate current and recent antibiotics on lab submission forms
must readmin on(or before) day 14 if infection not resolved completely

40
Q

What are the side effects of cephalosporins?

A
  1. GI issues if given orally - vomit, diarrhea, inappetance due to chemical irritation or disruption of GI flora, ALWAYS give WITH FOOD, needs to be written on the label
  2. Allergy and anaphylaxis - may or may not be related to penicillin allergy, incidence is lower than that seen in penicillins
  3. IM injections may be painful in lg anim
41
Q

What are aminoglycosides?

A

damages cell membrane and blocks protein synth
aerobic, gram -, bacteriocidal
Concentration dependant
hydrophilic
very severe adverse effects

42
Q

What are some commonly used amingoglycosides?

A

usually found in topical eye/ear/wound formulations/ointments
Ex. end in micin(mycin)
Gentamicin (ear drogs; can be used short term IV)
Neomycin (polysporin wound ointments)
Amikacin (broadest spectrum, infusion beads, can be used short-term IV)
Tobramycin (ophthalmic drops)

43
Q

What are the two most MAJOR adverse effects of ALL aminoglycosides? How does it occur, are they reversible or irreversible?

A

Nephrotoxicity (kidney damage) and ototoxicity (damage to the auditory nerves and inner ear)
occur commonly
nephro is reversible; cytotoxicity is irreversible

44
Q

What increases the risk of ototoxic and nephrotoxicity?

A

Inc risk w/ systemic admin; dec is used locally
Inc w/ longer duration of use
Inc in older patients and pre-existing renal or neurological issues

45
Q

What is nephrotoxicity?

A

very likely to occur if drug given systemically for more than 7 days
drug accumulates in renal tubule cells and is directly toxic to cells
Must monitor for urine cats to detect damage to renal cells
must monitor for plasma lvls to avoid toxic lvls - therapeutic drug monitoring
inc risk if very young, very old, hypotensive, pre-existing renal dz

46
Q

What is ototoxicity and neurotoxicity

A

damage to auditory nerves (deafness) and inner ear (vestibule toxicity)
From neuomycin, gentamycin most toxic (common in SA ear meds)
Common adverse effect of topical ear meds

47
Q

What increases the risk of ototoxicity and vestibular toxicity? What are the clinical signs? If you see them, what should you do before they are seen?

A

ruptured ear drum, broken skin, cats, older, extended dosing, if underlying neurological dz
Clin signs: loss of hearing, pain, head-tilt, loos of balance, horner’s syndrome (unequal pupils, droopy lid)
Stop meds > flush ear w/ saline > must be seen

48
Q

How can we use aminoglycosides safely?

A

not a first line antibiotic
not approved for use in food-prod anims
based on culture/sensitivity only
Usually given as local drug bc poor oral absorption so ok if dog licks, do not use longer than prescribed even if topical, only use systemically under specific circumstances
Use as per label - do not give more/longer than recommended, follow all contraindications
Do not use on pyogenic infection sites - inactivated by pus which is acidic)

49
Q

What are fluoroquinolones?

A

newest class of antibiotics
inhibits DNA replication; broad spectrum, -cidal
Reccomended use: 1. hospital-aqcuired infections (especially of the urogenital tract), 2. For other severe infections only if there is proven resistance t other older Ab classes
still a reserved class in human meds
ends w/ -floxacin
Enrofloxacin (baytril), danofloxacin (advocin)

50
Q

How do we use FLQ’s?

A

arguably over-used in vet med
Diff routes available (oral/injectable)
wide-spread and excellent tissue penetration - tx skin, resp and urinary infections
Newer drugs have 1x/d oral dosing
also found in many ear drops due to SID dosing
commonly used to tx bact infections in reptles
Not approved or labeled for use in horses

51
Q

What are adverse effects of FLQ?

A
  1. Disrupts joint formation in yg animals - causes bubble-like lesions in cartilage, avoid or use w/ caution in yg/growing animals, enrofloxacin can cause retinal damage in cats w/ potential for irreversible blindness
  2. High risk of creating antibiotic resistance
52
Q

What are some characteristics of tetracyclines?

A

binds to ribosomes and blocks protein synth, bacteriostatic, broadest spectrum of all antibiotic classes ( gram +/-, mycoplasma, rickettsial organisms like lyme, anaplasmosis, erlichia)
Time dependant
lots of resistance - up to 30 diff bact resistance genes have been identified

53
Q

What are some commonly used tetracyclings?

A

3 gens; vets have access to 1 and 2, 3 (2005) is reserved for human resistant cases
Gen 1: tetracycline, oxytetracycline
Gen 2: minocycline, doxycycline
Seeing lots of resistance, esp to 1st gen
Ends in -cycline

54
Q

What are the indications for tetracyclines?

A

Commonly used in all SA and LA species
Doxycycline is drug of choice for tick borne dz and heartworm
subtherapeutic doses added to feed shown to enhance growth in poultry, calves, pigs but is banned for trade purposes in Europe, N. Am
Common to tx resp, urinary and skin infections, sepsis - including metaphylaxis of shipping fever

55
Q

What do we need to keep in mind if we use tetracyclines?

A

cattle and horses do not tolerate oral dosing
Check if formulation can be given IM, IV or SQ
There are short vs long-acting injectable forms
Long-acting IM forms are common in food animal prod with up to every 5/d dosing
WDTs are very short for both acting
IV injections ALWAYS over 10-20mins bc rapid IV will cause fatal arrhythmia and collapse
Usually PO route in SA - give 1-2hrs apart from dairy products. If given WITH dairy products, drugs will bind to Ca+ and not get absorbed, always follow with some water after admin PO

56
Q

What are the adverse effects of using tetracyclines?

A
  1. Binds to Ca, bone and teeth - causes yellow discoloration of teeth if given to yg anims/pregnant/nursing anims, may slow bone growth, avoid in preg/growing anims
  2. Nausea, vomit, diarrhea, inappetance - effects normal flora, helps if given w/ food (not dairy
  3. Esophageal necrosis - occurs if pill sticks to side of esophagus. Highest risk in cats, ** owners MUST flush w/ syringe of water
  4. Risk of Fatal arrhythmia if given fast IV - due to chelation of Ca in blood; Ca no longer available for muscle contraction, sudden collapse, death, horses most susceptible
57
Q

What tetracycle is used to treat contracted tendons in foals? How do we believe it works?

A

Oxytetracycline
believed to chelate Ca in muscles, therefore causes relaxation and allows limb to extend (followed by bandaging/splinting)
must be done in the first few days after birth

58
Q

What are sulfonamides?

A

Sulfa drugs w/ “sulfa” prefixes
Anti-metabolites that inhib folate synth to stop growth - bacteriostatic; broad spectrum
excellent tissue distribution - goes everywhere incl. CNS, prostate, eye
Lots of resistance, drug interactions and side effects
2 formulations
1. Feed additives stay in GI tract and are NOT absorbed; to tx coccidiosis in chickens
2. Systemic sulfa drugs given PO, IV, IM; enter plasma to tx tissue infections

59
Q

What is trimethoprim-sulfadiazine (TMP-S)?

A

Most commonly used systemic sulfa drug. “old drug”. Occasionally used in SA, horses
used in food anims in CAD; banned in USA

60
Q

What are the adverse effects of TMP-S?

A

Trimethoprim-Sulfadiazine
1. KCS - keratoconjuctivitis sicca or Dry eye: dex tear prod causes inc risk of corneal irritation and corneal ulcers, may be perma., watch for red eye, blinking, mucus coat over eyes
2. Allergic skin reactions/rashes
 Hives, redness, pruritus, hives
3. Crystallization of drug in the urine
 SA, dehydrated, if acidic pH
4. Anorexia, 5. Bone marrow suppression
6. Fever and polyarthritis, 7. Idiosyncratic fatal liver failure, 8. Hypothyroidism
9. Teratogen – deformities in the neural tube
due to folate deficiency, 10. Lots of drug interactions-fatal arrhythmias if
given with detomidine in horses.

61
Q

How are lincosamides and macrolides recognized by?

A

“mycin” ending, aminoglycosides also have same ending

62
Q

What are lincosamides?

A

bact protein inhibitors
bacteriostatic or cidal depending on conc, works against anaerobes, gram + aerobic cocci and toxoplasma parasites
distributed to milk and can cause diarrea in nursing young, can cross placenta, partially metabolized by liver
contraindicated for use in anims who rely on fermentation for digestion of food ex. horses, rodents, ruminants and rabbits

63
Q

What is clindamycin? Most coomon adverse ffect?

A

effecting drug for use in deep pyodermas, abscesses, dental infections, bite wounds and osteomyelitis. Given IM or PO
Most common adverse effect is GI upset
can happen with any admin route (po or IM)
inappetance, vomit, diarrhea, discontinue use usually recommended, may see hypersalivation or lip smacking in cats after PO admin, IM injection may see pain at injection site

64
Q

What are macrolides?

A

bacteriostatic by inhib protein synth
primarily used to tx gram+ bacterial resp dz
Tilmicosin, tylosin and tuliathromycin (draxxin) vet drugs

65
Q

What is tilmicosin?

A

Micotil trade name - common in beef cattle/sheep
Metaphylaxis and tx of bovine shipping fever
Long acting injectable, q72h
Give SQ only (slows down absorption as highly irritating if given IM
Improper use can cause cardiotoxicity by blocking Ca channels, tachycardia, dec cardia output, hypotension, CAN BE FATAl - if given IV, drug is contraindicated in horses, pigs, due to cardiotoxicity
Also reported in people handling drug

66
Q

What happens with accidental injection of micotil in people?

A

Can be fatal
exposure to scratches can cause severe inflam, pain,
low doze systemic exposure can cause dizziness, hypotension.
High doze systemic injection can cause a 5% cardiac arrest
Use needle/syringe safety especially w/ pressurized injection guns, multi-dose syringes, carrying loaded syringes in pockets

67
Q

What are some handling precautions to heed when using micotil?

A

never attach needle to syringe containing drug until ready to use
wear gloves, avoid eye contact - can be absorbed via conjunctiva)
never work alone with this drug, ensure proper restraint/chute system, lots of fatal drug interactions, so must be able to tell emerg workers name of drug, wash immediately in event of spills or accidental contact

68
Q

What is chloramphenicol and its handling precautions

A

Chloramphenicol - used to tx a variety of anaerobic bact infections in sm anims and horses, banned in food anims bc risk of fatal aplasic anemia in humans
Wear gloves when handling and avoid inhalation of powder, wash hands after handling tablets or capsules
need to ensure owners are aware of fatal effects, inhibs cyp450 enzymes

69
Q

What is florfenicol - nuflor?

A

similar to choramphenicol but lacks functional group that causes aplastic anemia
Common in feedlot cattle/swine, only approved for ^^, WDT
Cattle: metaphylaxis and tx of bovine shipping fever, foot rot and infectious bovine keratoconjuctivitis, long-acting IM inject
Swine: added to feed for resp infections

70
Q

What are the adverse side effects of florfenicol?

A
  1. Local tissue reaction - can cause tissue loss @ slaughter- go for neck/check, very bad if more than 10ml/site given IM
  2. Inappetance, diarrhea
  3. Dec water consumption
  4. Reversible bonemarrow suppression
  5. inc residues in enviro if using for metaphylaxis in feedlots
    Banned in dairy, avoid in horses due to possible fatal acute colitis
71
Q

What is metronidazole?

A

Bacteriocidal
Common to tx SA diarrhea. Anti-protzoal (coccidia, giardia, trichomonas), clostridia and other anaerobes (hoof abcesses - eq)
can give on empty stomach but may cause vomit/anorexia in SA
Must dilute and neutralize if IV
treated cattle cannot be slaughtered for food

72
Q

What are some side effects @ therapeutic dose for metronidazole?

A

neurological effects (ataxia, vestibular signs, head tilt, abnormal nystagmus, disorientation)
tremor and seizures

73
Q

What is prostora

A

probiotics made by Iams
Live bact genetically modified to be resistant to metronidazole and given with ^^

74
Q

How can we limit antibiotic resistance?

A
  1. right drug for right bug
  2. maintain therapeutic range
  3. tx until infection resolved
  4. only dispense 1 course @ a time
  5. Preventing residues (WDTs)
  6. Address hygiene, husbandry, wound care
  7. Client communication to ensure owner compliance
75
Q

How does giving the right drug for the right bug limit antibiotic resistance?

A

avoid sending ABC’s to pacify owners
perform culture and sensitivity testing to ensure correct drug
avoid prophylactic care

76
Q

How does giving the maintaining the therapeutic range limit antibiotic resistance?

A

correst mg/kg dose, correct frequency of dosing, correct route of admin, avoid ELDU

77
Q

How does treating the infection until its resolved limit antibiotic resistance?

A

ensure negative culture, have patient back for recheck, do not stop bc sings have resolved
Will be in subtherapeutic range and still be present in the body!!

78
Q

How does only dispensing one course at a time limit antibiotic resistance?

A

no “standing” repeats for antibiotics
prevents hoarding and/or intermittent use

79
Q

What are important things to do in regards to client communication?

A
  1. explain dosing frequency
  2. Finishing the prescribed amount
  3. Show owners how to give
  4. Emphasize need for rechecking to ensure infection has resolved
  5. Go over side effects
  6. Give WDT if food animal OR horse
  7. Follow-up
80
Q

What is the purpose of antifungals? Mechanism of action?

A

Used to treat mycoses or fungi dz’s
Infections can be superficial (malassezia, dermatophytes) or systemic (blastomycosis)
Mechanism - damage cells; usually cell membranes, blocks cell replication
drugs must be protected from light

81
Q

What are some adverse effects of antifungals

A

Lower TI than antibiotics - fungi and animal cells are both ukaryotic, lots of common structures and proteins
Consider al to be teratogenic - never use in any pregnant animal, wear gloves if you are pregnant

82
Q

WHat are the different classes of antifungals?

A

polyenes - amphotericin B, nystatin
azoles - Ketoconazole, itraconazole, fluconazole
Antimetabolites
superficial anti-dermatophytes - griseofulvin B

83
Q

What are polyenes?

A

ex. nystatin, amphotericin B
binds to sterols loc in fungal cell membrane and punches holes into cells
very severe side effects if systemic (binds cholesterol in patient’s cell membranes. Kidney damage in 80% of patients @ therapeutic dose)
Severity of dz must justify systemic use

84
Q

What formulations of polyenes are there?

A
  1. IV injectable - amphotericiin B to tx severe systemic mycosis, rapid onset (hours), will cause systemic toxicity
  2. Topical polyenes - nystatic
    local application dec systemic toxicity
    commonly found in skin creams (polysporin, diaper creams) and ear drops, very poor oral bioavailability
85
Q

What are azoles?

A

1st choice of antifungals when possible due to fewer side-effects

ketoconazole, fluconazole
disrupts fungal cell membrane synthesis
fewer side effects than polyenes, but slower onset of action 5-10d
oral, injectable and topical formulations
commonly used in ringworm, allergic yeast dermatitis, very severe yeast otitis

86
Q

What are the side effects of azoles?

A
  1. GI upset - nausea, vomit, inappetence. Can dec by splitting single lg dose to sm ones throughout the day
  2. Hepatotoxicity - older anims, pre-existing liver damage, prolonged tx
  3. Inhibs cytochrome P450 activity
  4. Dec steroid prod - suppresses adrenal gland func. ketoconazole to tx cushings dz; damages adrenal glans in reversible manner. Can cause iatrogenic addison’s dz
  5. Teratogenic
87
Q

What is griseofulvin?

A

tx of superficial dermatophytoses (ringworm) in k9, fel, eq
oral formula only
adverse effects: GI effects - inappetence, V/D, teratogenic (never use in preg anims)
cats: more susceptible to toxic effects

88
Q

What are virus infections? How can we stop virus infections?

A

Cannot replicate on their own
Must infect cell and use host cell’s enzymes to replicate
1. inactivate free virion
2. Prevent attachment/entry
3. kill virus factories (infected host cells)
4. block viral enzyme involved in replication -very few of these; most are hard to access and rapidly mutate

89
Q

How do we prevent and treat viral infections?

A

txing is hard bc it damages body’s own cells
Antibiotics do NOT work
Most effective to tx is to boost body’s immune response by vx’s

90
Q

What is AZT?

A

An antiviral
drug to treat HIV in humans
inhibs viral RNA replication enzymes
has been used to tx FIV ($$$)

91
Q

What is acyclovir?

A

Vet antiviral
treats herpes virus (feline herpesvirus)
inhibs viral DNA replication
GI s/e if oral

92
Q

What are class 1 interferons?

A

non-specific anti-viral; works against all viruses
part of innate immune response and blocks entry of virus into adjacent cells
questionable efficacy, but few side effects
used to treat severe FURD, FeLV, FIP

93
Q

What is lysine?

A

An amino acid
nutraceutical; OTC
anti-herpes virus activity (resp dz in cats)
available as powders, foams, gels, treats

94
Q

Give a summary of antivirals

A

preventing transmission and vx’s are keystone to control viral infections
limited # of anti-virals exist
limitations due to virus have limited targets
limited due to intracellular infection
risk/damage to infected host cells

PHARMACOLOGY (12 decks)

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