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Clinical Pharmacology Final > Antibacterial agents > Flashcards

Antibacterial agents Flashcards

1
Q

Cell wall synthesis inhibitors

A
  • Penicillins

- Cephalosporins

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2
Q

What are the five groups of penicillins?

A
  1. Natural penicillins (Penicillin G**)
  2. Aminopenicillins**
  3. Anti-staph penicillins
  4. Anti-pseudomonal penicillins
  5. Beta-lactamase inhibitor combinations (Amoxicillin clavulanate*)
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3
Q

How many generations of cephalosporins?

A
  • 3
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4
Q

Which penicillins are used the most in vet med?

A
  • Penicillin G*
  • Aminopenicillins* (Amoxicillin, ampicillin, others)
  • Amoxicillin clavulanate**
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5
Q

Cephalosporins used frequently in vet med?

A
  • Cephalothin, cephalexin, cefazolin*

- Ceftiofur, cefpodoxime, cefovecin, ceftriaxone

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6
Q

Other beta lactams that are used in human med

A
  • Imipenem
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7
Q

Glycopeptides used in human med

A
  • Vancomycin
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8
Q

Protein synthesis inhibitors

A
  1. Tetracyclines
  2. Aminoglycosides
  3. Amphenicols
  4. Macrolides
  5. Lincosamides
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9
Q

Which are the natural penicillins?

A

Penicillin V and Penicillin G

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10
Q

What are the aminopenicillins?

A
  • Amoxicillin, ampicillin, others
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11
Q

What are the anti-staph penicillins?

A
  • Methicillin, cloxacillin, dicloxacillin, oxacillin
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12
Q

What are the anti-pseudomonal penicillins?

A
  • Ticarcillin, piperacillin, carbenicillin
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13
Q

What are the beta lactamase inhibitor combinations?

A
  • Amoxicillin clavulanate; others
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14
Q

What are the 1st gen cephalosporins?

A
  • Cefadroxil, cephalothin, cephalexin, cefazolin
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15
Q

What are the 2nd gen cephalosporins?

A
  • Cefaclor, cefoxitin, others
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16
Q

What are the 3rd gen cephalosporins?

A
  • Ceftiofur, cefpodoxime, cefovecin, ceftriaxone
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17
Q

What are the tetracycline family drugs?

A
  • Tetracycline, oxytetracycline, doxycycline
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18
Q

Aminoglycoside family

A
  • Gentamicin, Amikacin, tobramycin (ophthalmic), neomycin (topical)
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19
Q

Amphenicols family

A
  • Chloramphenicol, florfenicol, thiamphenicol
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20
Q

Macrolides family

A
  • Erythromycin, tilmicosin, azithromycin, tylosin, tulathromycin
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21
Q

Lincosamides family

A
  • Lincomycin, clindamycin
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22
Q

Antimetabolite drugs

A
  1. Sulfonamides
  2. Folate reduction inhibitors
  3. Potentiated sulfonamides
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23
Q

Sulfonamide drugs

A
  • Sulfadiazine, sulfasalazine
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24
Q

Folate reduction inhibitors

A
  • Trimethoprim, ormetoprim, pyrimethamine
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25
Q

Potentiated sulfonamides

A
  • Trimethoprim-sulfa; ormetoprim-sulfdaimethoxine
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26
Q

Nucleic acid synthesis inhibitors

A
  1. Fluoroquinolones
  2. Rifampin
  3. Metronidazole
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27
Q

Fluoroquinolone examples

A
  • Enrofloxacin
  • Orbifloxacin
  • Difloxacin
  • Marbofloxaacin
  • Danofloxacin
  • Ciprofloxacin
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28
Q

MOA of Beta-lactams**

A
  • All are considered bactericidal**
  • Targets penicillin binding protein and bind the bacterial transpeptidase enzymes (AKA penicillin binding proteins) that disrupt the wall
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29
Q

Vancomycin MOA

A
  • Binds precursors of peptidoglycans interfering with bacterial cell wall synthesis
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30
Q

What are the two important mechanisms of resistance to penicillins?***

A
  1. Enzymatic destruction by Beta-lactamases produced by bacteria*** (cephalosporin lactam ring is more resistant)
  2. Altered target** (altered penicillin binding protein)
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31
Q

Mechanism of resistance of vancomycin

A
  • Altered target (peptide)
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32
Q

Penicillins susceptibility for Gram +/Gram - and Aerboci/Anaerobic***

A
  • USE THE QUADRANT CHART THAT HE HAS TO REMEMBER THIS
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33
Q

Natural penicillins and aminopenicillins efficacy against Pseudomonas and Staphylococcus***

A
  • NOT EFFECTIVE AGAINST PSEUDOMONAS OR STAPHYLOCOCCUS
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34
Q

Anti-pseudomonal drugs susceptibility to beta lactamase

A
  • Susceptible to beta lactamase
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35
Q

Penicillins for aerobic and Gram +

A
  • Natural
  • Aminopenicillins
  • Antipseudomonal
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36
Q

Penicillins for aerobic and gram -

A
  • Natural (limited)
  • Aminopenicillins (better than Natural)
  • Antipseudomonal
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37
Q

Penicillins for anaerobic and gram +

A
  • natural P
  • Aminopenicillins (slightly less than nat Pen)
  • Anti-pseudomonal
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38
Q

Penicillins for anaerobic and gram -

A
  • Natural P (limited)
  • Aminopenicillins (slightly less than Nat P)
  • Antipseudomonal
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39
Q

***Cephalosporin activity

A
  • SEE THE CHAT**
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40
Q

Other beta-lactam spectrum fo activity***

A
  • SEE THE CHART
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41
Q

Imipenem-cilastin spectrum of activity***

A
  • Bactericidal
  • Cilastin merely inhibits rapid metabolism of imipenem in the renal tubules, prolonging its duration in the body
  • Both drugs are often reserved for very resistant organisms in human patients, so veterinary use should be limited**
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42
Q

Toxicity of beta lactams**

A
  • In general very safe
  • The most common adverse reaction is hypersensitivity (allergy) which can be life-threatening***
  • Some of the cephalosporins have been associated with renal failure (very rare)**
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43
Q

Which cephalosporins are useful against anaerobic bacteria?

A
  • Cefoxitin
  • Cefotetan (2nd gen)
  • The rest are weak
  • Useful for gram pos and gram neg
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44
Q

Spectrum for Imipenem

A
  • Gram +/Gram - aerobic and anaerobic
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45
Q

Spectrum of vancomycin

A
  • Aerobic gram + and Gram -
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46
Q

Beta lactam effect on GIT

A
  • Any antibiotic can potentially alter normal flora of the GIT resulting in diarrhea, and any drug can potentially irritate the stomach and small intestine, causing vomiting or inappetence
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47
Q

Procaine penicillin G racehorses

A
  • Can cause a positive procaine test reaction (consideration in performance animals, e.g. racehorses) for up to 2 weeks after injection
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48
Q

Vancomycin route

A
  • IV
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49
Q

Vancomycin adverse reactions

A
  • Rapid IV administration causes a hypersensitivity type reaction (histamine release)***
  • It has also occasionally been associated with renal toxicity, ototoxicity, and reversible thrombocytopenia and neutropenia***
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50
Q

Vancomycin use in food animals

A
  • Prohibited
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51
Q

Which beta lactams can be given PO?

A
  • Aminopenicillins**

- Beta lactamase inhibitor combinations***

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52
Q

How often do Na+/K+ salts of penicillin ned to be given?

A
  • QID (disadvantage)
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53
Q

Potassium penicillin use

A
  • Commonly used in foals needing intensive care**

- IV

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54
Q

PPG use

A
  • Commonly used in horses and cattle

- Often given IM (large amounts)

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55
Q

Use of benzathine penicillin G

A
  • Shipping fever complex (Strep, Staph aureus, Arcanobacterium pyogenes)
  • Blackleg (Clostridium chauvoei)
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56
Q

Use of Aminopenicillins

A
  • Horses (IV)
  • Cattle (amoxicillin intramammary)
  • Dogs and cats
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57
Q

Anti-staph penicillins use

A
  • Mastitis in dairy cattle
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58
Q

Use of anti-pseudomonal penicillins

A
  • Ticarcillin IV
  • Treat serious Gram negative infections in dogs
  • Intrauterine in mares
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59
Q

Beta lactamase inhibitor combo uses

A
  • Not used in large animals (no label for food animal; poor oral absorption horses)
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60
Q

Oral cephalosporins

A
  • Cefadroxil and cephalexin (1st gen)

- Cefpodoxime (3rd gen)

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61
Q

Cefadroxil and cephalexin oral bioavailability in horses

A
  • Very low**

- Otherwise most commonly used 1st generation cephalosporin

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62
Q

Cefazolin indication**

A
  • Used in dogs, cats, and horses

- Penetrate bone*** (prophylactically for orthopedic surgeries)

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63
Q

Cephapirin clinical use

A
  • Formulation for dairy cattle
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64
Q

Indication for cefoxitin and cefotetan

A
  • Used for abdominal surgical prophylaxis (dogs and cats)*** because of activity against Gram negative and some anaerobic organisms
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65
Q

Clinical use for ceftiofur

A
  • Treating UTI in dogs and cats (SQ) - not used a lot

- Treating respiratory infections in horses, cattle, and pigs**

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66
Q

Cefovecin or Convenia clinical use

A
  • Recently approved as a one-time injectable drug for treating skin infections in dogs and cats**
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67
Q

Cefpodoxime clinical use

A
  • Labeled for the treatment of skin infections once a day in dogs.***
  • It is not labeled for use in other species.
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68
Q

Carbapenems clinical use***

A
  • None are labeled for use in veterinary medicine, but are occasionally used in dogs, cats, and foals for severe, resistant infections***
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69
Q

Clinical use of vancomycin

A
  • Not labeled for use in vet med
  • Illegal to use in food animals
  • Occasionally used for resistant Staphylococcal (particularly MRSA) and/or Enterococcus infections in dogs, cats, and horses
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70
Q

Protein synthesis inhibitors mechanism of action

A
  • See image
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71
Q

Tetracycline MOA

A
  • Targets 30s ribosomal subunit

- Bacteriostatic**

72
Q

Amphenicols/Macrolides/Lincosamides MOA

A
  • Targets 50S

- Bacteriostatic

73
Q

Aminoglycosides MOA

A
  • Targets 30S ribosomal subunit to cause production of a misfolded protein
  • Dictates that membrane function will change
  • Bacteriocidal***
74
Q

Resistance to Tetracycline MOA

A
  • Efflux pump that transports the drug out of the bacterial cell; therefore, the drug fails to reach its target. Plasma encoded.

resistance to one tetracycline produces cross resistance to another**

75
Q

Resistance to Lincosamides/macrolides/amphenicols MOA

A
  • Inactivation/degradation by bacterial enzymes
76
Q

Resistance to Aminoglycosides MOA

A
  • Inactivation/degradation by bacterial enzymes

- Failure to reach the target because of decreased porin size occurs in some gram negative organisms

77
Q

Spectrum of tetracycline

A
  • Aerobics and anaerobics

- Gram pos and gram neg

78
Q

Spectrum of Aminoglycosides

A
  • Aerobics

- Gram pos and Gram neg

79
Q

Spectrum of Clindamycin**

A
  • Gram + aerobes and anaerobes (except Clostridium difficile)
80
Q

Spectrum of macrolides

A
  • Original only Gram + aerobes

- Newer have broad spectrum activity against Gram +/Gram - Aerobes and Anaerobes

81
Q

Inherent resistance to tetracyclines and amphenicols

A
  • Staph, Pseudomonas, and E. coli should be considered resistant to tetracyclines until proven otherwise
82
Q

Inherent activity of tetracyclines and amphenicols

A
  • Rickettsiaceae and Anaplasmataceae, and Chlamydia
83
Q

Toxicity of tetracyclines

A
  • GI side effects including anorexia, vomiting, and diarrhea***
  • Rapid IV administration in many species has resulted in collapse (possibly due to calcium chelation?). In horses, IV administration of doxycycline can be fatal***
  • Permanent brown discoloration of teeth if administered during tooth development.
  • Other side effects include drug-induced fever, renal toxicity, hepatic toxicity*** (seeing more doxycycline-induced recently), and allergic reactions
84
Q

Tetracyclines in horses

A
  • Assume that they may develop diarrhea just inherently

In horses, IV administration of doxycycline can be fatal***

  • Including anorexia, vomiting, and diarrhea
85
Q

Doxycycline in cats

A
  • Particularly prone to esophageal lesions (fibrosis and stricture) caused by tetracyclines**
  • Any dose should be followed by water to prevent lodging of a tablet or capsule in the esophagus
  • Doxycycline hyclate (rather than doxycycline monohydrate) is associated with more esophageal damage
86
Q

Aminoglycosides toxicity

A
  • Nephrotoxicity***, ototoxicity, and neuromuscular blockade
87
Q

Nephrotoxicity of aminoglycosides

A
  • Relatively common - 25% of human patients receiving aminoglycosides for 3 days or more experience nephrotoxicity! Aminoglycoside concentrations are 50 times in renal tissue than in plasma
88
Q

How to mitigate nephrotoxicity of aminoglycosides

A
  • Use the least toxic aminoglycoside (amikacin is thought to be less likely than gentamicin to cause nephrotoxicity)
  • Do not use in patients that are hypovolemic
  • Avoid concurrent use of other nephrotoxic drugs (furosemide, NSAIDs)
89
Q

Otoxocitiy of aminoglycosides

A
  • Ototoxicity is irreversible
  • Can include both auditory and/or vestibular toxicity
  • Ototoxicity can occur with topical, particularly otic, or systemic administration
  • Ensure tympanic membrane is intact
  • Otic administration of aminoglycosidess should be avoided in patients with a ruptured tympanic membrane
  • Auditory toxicity is more common in dogs than in cats while vestibular toxicity is more common in cats than dogs
90
Q

Neuromuscular blockade and aminoglycosides

A
  • Reversible
  • Risk is greatest at high doses (rapid IV administration) or when combined with other agents acting at the neuromuscular junction (anesthetics, skeletal muscle relaxants)
91
Q

Chloramphenicol use in small animals

A
  • Frequently avoided due to the potentiaal for a human toxicity (irreversible aplastic anemia)
  • Can cause a reversible bone marrow suppression in dogs and cats
92
Q

Chloramphenicol drug interactions

A
  • Inhibits CYP 450 enzymes

- many drug interactions

93
Q

Advantages of florphenicol over chloramphenicol

A
  • Developed for use in food animals
  • It is not associated with aplastic anemia in people so it is not prohibited in food animals
  • Does not inhibit CYP 450 enzymes. I
94
Q

Florphenicol use in horses

A
  • Can cause severe diarrhea in horses
95
Q

Erythromycin adverse effects

A
  • Frequently causes GI upset and vomiting
  • Thought to result from its interaction with the motilin receptor which stimulates GI motility (sometimes used as prokinetic). Newer macrolides do not have this effect.
96
Q

Macrolides in horses

A
  • Frequently used in foals (particularly for Rhodococcus equi pneumonia)
  • Use in adult horses is frequently associated with severe colitis; therefore, use of macrolides should be avoided in adults
  • Hyperthermia in foals***
97
Q

Tilmicosin adverse effects*****

A
  • Can cause severe cardiovascular toxicity at high doses in cattle, and even in low doses can e fatal in swine, horses, goats, and people
  • Other macrolides do not share this adverse effect
98
Q

Tilmicosin antidote

A
  • No antidote
99
Q

Lincosamides in horses

A
  • Generally not used because they can cause an overgrowth of Clostridium difficile resulting in severe pseudomembranous colitis
100
Q

Lincosamides drug interactions

A
  • Clindamycin especially in small animals
  • Often used in combination therapy
  • Avoid using lincosamides concurrently with other drugs that bind to the 50s ribosome (amphenicols and macrolides)
  • Can use with beta lactams
101
Q

What is the most commonly used tetracycline in large animal vet med?

A
  • Oxytetracycline
  • Used for treating bovine respiratory diseases, mastitis, and anaplasmosis
  • Intrauterine infusion of oxytetracycline is used for cows with retained fetal membranes (extralabel)
  • In horses, oxytetracycline has been used to treat Neorickettsia risticii (Potomac horse fever)
102
Q

Most commonly use tetracycline in small animal vet med?

A
  • Doxycycline
103
Q

Doxycycline route

A
  • PO

- Injectable

104
Q

Doxycycline distribution**

A
  • Lipophilic and thus penetrates tissues well and is considered the drug of choice for treating intracellular pathogens such as Ehrlichia, Rickettsia, and Mycoplasma including M. haemofelis (formerly called haemobartonella felis)
105
Q

Doxycycline use for UTI**

A
  • Does not achieve high concentrations in urine

- Not a good choice for UTIs

106
Q

What are most commonly used aminoglycosides in vet med?

A
  • Gentamicin (LA)
  • Amikacin (SA)
  • Neomycin
107
Q

What are differences of gentamicin and amikacin?

A
  • Amikacin is less susceptible to bacterial inactivation than gentamicin
  • Amikacin is potentially less likely to produce nephrotoxicity
  • Amikacin is more expensive than gentamicin
108
Q

Gentamicin use

A
  • Frequently used in horses systemically as part of PPG

- Gentamicin is also used for regional limb perfusion to treat lower limb bone and joint infections

109
Q

Amikacin species use

A
  • Foals, dogs, and cats

- Amikacin also used as intrauterine infusion for horses

110
Q

Amphenicols distribution

A
  • Lipid soluble**

- Achieve high concentrations within cells and can gain access to tissues such as CNS and prostate

111
Q

Chloramphenicol clinical use**

A
  • In small animals used primarily for CNS infections, some rickettsiae, and mycoplasma
  • Chloramphenicol is sometimes used in horses (has reasonable oral bioavailability and does not cause serious adverse effects on the GI flora), but is ILLEGAL for use in food animals
  • Not used much in small animals
112
Q

Florphenicol clinical use

A
  • Approved for use as an injectable (IM or SQ) for treating bovine respiratory disease and bovine interdigital phlegmon (foot rot)
113
Q

Macrolides distribution

A
  • Lipid soluble (especially azithromycin) and are therefore useful against susceptible intracellular bacteria
  • Because of its long tissue half-life in the respiratory tract, it has unusual dosing recommendations (once every 3 days; OR once a day for 3 days then stop)
114
Q

Which macrolides are most often used for small animals and horses?

A
  • Erythromycin, azithromycin, and clarithromycin
115
Q

Clinical use of macrolides in small animals and horses

A
  • In horses, clarithromycin and azithromycin are effective for treating Rhodococcus equi infections (one paper suggested that erythromycin plus rifampin was best)
  • They are used in dogs and cats to treat a variety of respiratory infecitons (not used as much)
116
Q

Newer macrolides

A
  • Gamithromycin
  • Tulathromycin
  • Tilmicosin
117
Q

Use of newer macrolides

A
  • Approved for use as an injectable (IM or SQ) for treating bovine respiratory disease and bovine interdigital phlegmon (foot rot)
  • Tulathromycin quite common
118
Q

What is the most commonly used lincosamide?

A
  • Clindamycin***
119
Q

***What is clindamycin most commonly used for in SA?

A
  • Wounds, abscesses, periodontal disease, and osteomyelitis
120
Q

Drugs that are analogs of PABA

A
  • Sulfadimetoxine
  • Sulfadiazine
  • Sulfametoxazole
121
Q

Folate reduction inhibitors

A
  • Ormetoprim

- Trimetoprim

122
Q

Combinations of analogs of PAbA and folate reduction inhibitors

A
  • Sulfadimetoxine with ormetoprim
  • Sulfadiazine with trimethoprime
  • Sulfametoxazole with trimethoprim
123
Q

What enzyme do sulfas inhibit?

A
  • Dihydropteroate synthase
124
Q

What enzyme does trimethoprim inhibit?

A
  • Dihydrofolate reductase
125
Q

MOA of antimetabolites

A
  • See chart
  • Both inhibit tetrayhydrofolic acid (active form of folic acid) through different mechanisms
  • This is used for protein synthesis by bacteria
  • Bacteriostatic used alone
126
Q

Combination of sulfonamide with a folate reduction inhibitor

A
  • Synergistic and bacteriocidal
127
Q

MOA of resistance for antimetabolites

A
  • There are numerous mechanisms of resistance to the antimetabolites; the most important plasmid-mediated form of resistance is impaired penetration
  • This resistance has limited the clinical utility of these drugs in many clinical situations
128
Q

Spectrum of potentiated sulfonamides

A
  • Aerobes, Gram + and Gram -
129
Q

Which bacteria should you not use potentiated sulfonamides for?

A
  • NOT good choices for Staph, Enterococcus, E. coli, Proteus, Klebsiella, Pseudomonas
  • Many anaerobes
  • If you don’t do a susceptibility test, you wouldn’t know
130
Q

Adverse effects of sulfonamides

A
  • Most important adverse effect is hypersensitivity reaction, which occurs in people too
  • Immune-mediated diseases ranging from mild to severe can affect skin, liver, kidney, hematopoietic system, and eyes
  • Keratoconjunctivitis sicca (KCS; decreased tear production by the lacrimal glands), and it is recommended that the patient be monitored during treatment with Schirmer tear tests*** (monitor a baseline, then monitor over time)
  • If a decrease in tear production is noted, the drug should be discontinued, with normal tear production expected to resume
  • Check tear production at same time every day
131
Q

Sulfonamides and nephrotoxicity

A
  • Rarely, nephrotoxicity** associated with sulfonamide crystalluria has been reported in DOGS
  • Sulfonamides are metabolized by acetylation - because dogs lack this metabolic pathway, they are more likely to develop adverse effects than other species
  • Be careful in animals with kidney disease or when using other drugs that can cause kidney damage
132
Q

Clinical use of sulfonamides and potentiated sulfonamides

A
  • Available in a variety of forms (oral, injectable, feed additives) with indications including treatment of intestinal…
  • Infections in CNS, joints (synovial fluid) coccidiosis
  • Bacterial enteritis
  • Bacterial pneumonia
  • Skin and soft tissue infections in dogs and cats
  • Cystitis and prostatitis in dogs
133
Q

Clinical use of Sulfadimethoxine (Albon)

A
  • Labeled for use in many species
134
Q

Clinical use of Sulfadimethoxine + ormetoprim (Primor)

A
  • Labeled for use in dogs
135
Q

Clinical use of sulfadiazine + trimethoprim (Tribrissen)

A
  • labeled for use in horses; availability for dogs and cats has declined
136
Q

Clinical use of sulfamethoxazole + trimethoprim

A
  • Most common human formulation but used off-label in dogs, cats, and horses
137
Q

Sulfonamides use in food animals

A
  • Sulfonamides have caused the most tissue residue violations in the US with the greatest problems coming from pork, veal, and poultry
138
Q

Nucleic acid synthesis inhibitors

A
  1. Fluoroquinolones (Enrofloxacin, orbifloxacin, difloxacin, marbofloxacin, danofloxacin ciprofloxacin)
  2. Rifampin
  3. Metronidazole
139
Q

MOA of Fluoroquinolones

A
  • Inhibit the bacterial DNA gyrase (topoisomerase II) enzyme which is necessary for transcription, translation, and bacterial replication.
  • Bacteriocidal
140
Q

Folic acid inhibitor toxicity

A

Not toxic

141
Q

MOA of Rifampin

A
  • Bactericidal at high concentrations**

- Rifampin inhibits DNA-dependent RNA polymerase interfering with RNA synthesis

142
Q

MOA of Metronidazole

A
  • Bactericidal
  • By an undefined mechanism, metronidazole impairs microbial RNA and DNA synthesis
  • Induces free radical production in the bacteria
143
Q

MOA of resistance for fluoroquinolones

A
  • Alteration of the target (Topoisomerase II)
  • Decreased porin size (how it gets into the cell) by gram negative bacteria, resulting in failure of the drug to reach its target
144
Q

Rifampin MOA of resistance

A
  • Alteration of drug target

- If used as a sole agent, resistance often develops, rapidly limiting the usefulness of this drug***

145
Q

Metronidazole MOA of resistance

A
  • Unknown, but resistance exists
146
Q

Fluoroquinolones spectrum

A
  • Fluoroquinolones aerobic Gram + and Gram -

- Ineffective against anaerobes***

147
Q

Metronidazole spectrum

A
  • Anaerobic gram + and Gram -
148
Q

Rifampin spectrum

A
  • Gram + aerobic
149
Q

Spectrum of Pradofloxacin

A
  • Gram + Anaerobic
  • Next generation fluoroquinolone that is FDA approved for cats
  • Has greater gram positive and anaerobic activity while maintaining gram negative activity
  • For cats, the only specific antibiotic you have for anaerobic gram positive bacteria, as metronidazole is toxic in cats
150
Q

Toxicity of Fluoroquinolones in young animals

A
  • Irreversible cartilage damage in growing animals (documented in dogs and foals); therefore, fluoroquinolones should not be used in growing animals
151
Q

Toxicity of Fluoroquinolones in cats

A
  • Retinopathy in cats that results in irreversible blindness
  • This tends to be related to higher doses, or use in cats with compromised renal function
  • Polymorphism in the transporter in the eyes
  • Keep the cat inside to avoid this
152
Q

Toxicity of Fluoroquinolones in general

A
  • at high plasma concentrations such as those achieved after IV injection or extremely high oral doses, seizures can be induced by fluoroquinolones**
153
Q

Rifampin toxicity

A
  • Liver toxicity

- Can cause a red-orange discoloration of urine

154
Q

Rifampin drug interactions

A
  • It induces drug metabolizing enzymes so drug interactions are a concern
155
Q

Metronidazole toxicity

A
  • Dose-dependent vestibular toxicity (generally slowly reversible)
  • Neurotoxicosis in two cats**
  • Genotoxicity of PBMCs (monocytes) appears to resolve within 7 days of discontinuing administration
156
Q

Which fluoroquinolones are FDA approved for dogs and cats or dogs?

A
  • Dogs and cats: Enrofloxacin, marbofloxacin, orbifloxacin

- Dogs only: Difloxacin

157
Q

Advantage of fluoroquinolones over aminoglycosides

A
  • Lower incidence of side effects than aminoglycosides in general
  • Otherwise spectrum of activity is very similar
158
Q

Distribution of Fluoroquinolones

A
  • Lipid soluble and achieve high intracellular concentrations and penetrate tissues including prostate, respiratory tract, and CNS
159
Q

Fluoroquinolones and UTIs

A
  • All of the veterinary labeled drugs except for difloxacin achieve high concentrations in urine and are therefore good choices for resistant urinary tract infections
160
Q

Fluoroquinolones in horses approval

A
  • No FQ approved for use in horses
  • Enrofloxacin is most commonly used (orally and by injection)
  • Orbifloxacin and marbofloxacin are available too (not used often due to cost)
161
Q

FQ in cattle clinical use

A
  • In cattle, enrofloxacin, and danofloxacin are approved for treating bovine respiratory disease
  • Extralabel use of fluoroquinolones in food animals is illegal***
162
Q

FQ in poultry clinical use

A
  • Because of potential for causing spread of resistant Campylobacter, fluoroquinolones that were once approved for use in poultry were pulled from the market
163
Q

FQ Absorption

A
  • Well absorbed after oral administration, although drug interactions do occur
  • Divalent (magnesium and calcium) and trivalent (aluminum) cations significantly decrease oral bioavailability and can lead to therapeutic failure (so be careful if your patient is drinking milk)
164
Q

FQ drug interactions

A
  • FQs inhibit cytochrome P450 drug metabolizing enzymes, which can cause an increase in plasma concentrations of some drugs if concurrently administered with fluoroquinolones
  • Especially enrofloxacin
165
Q

Rifampin clinical use

A
  • In vet med, rifampin is used mainly in combination with macrolides for treating Rhodococcus equi pneumonia in foals
166
Q

Metronidazole approval

A
  • No FDA approved vet formulations
167
Q

Metronidazole clinical use

A
  • Highly lipid soluble, therefore distributes well to the CNS and into abscesses
  • It is used to treat anaerobic infections in dogs and horses primarily
  • Too neurotoxic for cats
168
Q

Metronidazole in food animals

A
  • ILLEGAL in food animals and current formulations are inconvenient for dosing cats
169
Q

MRSA infections options

A
  • Chloramphenicol
  • Tetracycline (doxycycline, minocycline)
  • Aminoglycosides (gentamicin, amikacin)
  • Rifampin
  • Drugs to consider if a susceptibility test can confirm activity
170
Q

Pseudomonas infection options

A
  • Amikacin and gentamicin
  • 2nd or 3rd generation cephalosporins
  • Anti-pseudomonal penicillins (ticarcillin, piperacillin, carbenicillin; piperacillin-tazobactam
  • Imipenem (IV therapy)
  • Fluoroquinolone, combined with beta-lactam
  • In many situations aminoglycosides and fluoroquinolones are not effective
  • In many times just the 3rd gen cephalosporins and anti-pseudomonal penicillins
171
Q

Nocardia abx

A
  • Potentiated sulfonamides
172
Q

Mycoplasma abx

A
  • Tetracyclines
  • Macrolides
  • Amphenicols
173
Q

Rickettsiaceae and Anaplasmataceae abx

A
  • Tetracyclines
174
Q

Abx for Gram + anaerobes

A
  • Pradofloxacin (cat)
  • Clindamycin
  • Metronidazole (no cat)
  • Aminopenicillins
  • Natural penicillins
  • Tetracyclines
  • Newer macrolides
175
Q

Abx for Gram - anaerobes

A
  • Pradofloxacin (cat)
  • Metronidazole (no cat)
  • Aminopenicillins
  • Amphenicols
  • Newer macrolides
176
Q

Four quadrant antibiotics (pick for empirical treatment)

A
  • Ampicillin with enrofloxacin (avoid in young animals)
  • Amoxicillin/clindamycin/metronidazole + fluoroquinolones (dog) - Avoid in young animals
  • Amoxicillin/clavulanic (cat)
  • Imipenem (not an option for empirical and ambulatory treatment)
  • Penicillin and gentamicin or amikacin (not for ambulatory treatment)
  • Tetracycline, amphenicols, and newer macrolides (small animals??)

Clinical Pharmacology Final (2 decks)

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