Miscellaneous

Question 1

What is a drug (human) under the nitromidazole class? Formulations?

Answer 1

Metronidazole (human products)

- oral, IV and topical cream

Question 2

What is the MOA of metronidazole?

Answer 2

intracelljlar anaerobic metabolism of drug produced reactive metabolites = DNA damage

Question 3

What is the SOA of metronidazole?

Answer 3

Anaerobes (clostridium, bacterioides, brachyspira)

protozoa (trichomonas, campylobacter)

limited against aerobes

Question 4

Can resistance occur with Metronidazole?

Answer 4

rare, but can with intracellular drug activation

- cross resistance between nitromidazoles

Question 5

what is the PK of metronidazole?

Answer 5

good oral F
penetrates many tissues (incl CSF and bone)
eliminated: hepatic metabolism, excreted bile and urine

Question 6

What are the AEs of metronidazole?

Answer 6

potential carcinogen (banned in food)
may be teratogenic (not for pregnant)
minimal GI upset (salivation, inappetence)
neuro: ataxia, seizures, lethargy (Tx: Diazapam)

Drug interactions:
- caution when using with microsomal enzyme (CYP) inducer/inhibitor

Question 7

What are 2 drugs in the nitrofuran class?

Answer 7

Nitrofurazon (topical vet)
- wound cream (not for food animals)

Nitrofurantoin (oral human)
- e.coli/MDR UTIs in dogs and cats

Question 8

What antimicrobial can be used to treat e.coli/MDR UTIs?

Answer 8

Nitrofurantoin

Question 9

what is the MOA of nitrofurans?

Answer 9

block bacterial pyruvate metabolism (no energy)

Question 10

what is the SOA for nitrofurans?

Answer 10

broad

especially gram - enterics

Question 11

What is the problem with nitrofuran effectiveness?

Answer 11

reaching MIC levels in plasma requires dose that causes systemic toxicity

Question 12

Is resistance a problem with nitrofurans?

Answer 12

does occur (not common)
- no cross resistance with other classes

Question 13

What is the PK of nitrofurans?

Answer 13

good oral absorption
topical absorption unknown
wide distribution
excretion: renal (high concentrations in urine (even low dose)

Question 14

What are the AEs of nitrofurans?

Answer 14

cardiomyopathy (ventricular dilation)

reproductive (endocrine) toxicity

carcinogenic (banned in food animals)

Question 15

What Rifampin formulations are used?

Answer 15

human tablets

Question 16

What is the MOA of Rifampin?

Answer 16

inhibits bacterial RNA polymerase
penetrates leukocytes (well for intracellular)

Question 17

What is the PK-PD relationship for Rifampin?

Answer 17

bacteriostatic

time dependent activity

Question 18

What is the SOA of Rifampin?

Answer 18

broad but high resistance (esp gram - )

Question 19

What are common infections Rifampin would be used to teat?

Answer 19

Mycobacterium (TB)
staph isolates
rhodococcus equi (pneumonia in foals)

Question 20

Is resistance a problem with Rifampin? How? what can be used in conjunction to avoid resistance?

Answer 20

emerges quickly
- single amino acid change in bacterial RNA polymerase reducing binding on antibiotic

use along with erythromycin or others

Question 21

what is the PK of Rifampin?

Answer 21

good oral F
wide distribution to variety of tissues
hepatic metabolism
biliary and renal excretion

Question 22

What are the AE of Rifampin?

Answer 22

red tinged fluides (urine, sweat, saliva) - no concern

Hepatic CYP and P-gyp enzyme induction (increases clearance of other drugs)

teratogenic

Blood dyscrasias (rare) - anemia, decrease platelets

Question 23

What glycopeptide antimicrobial should not be used in vet med?

Answer 23

vancomycin (oral, injectable)

Question 24

What is the MOA of vancomycin?

Answer 24

inhibits peptidoglycan synthesis for cell wall

Question 25

What is the SOA for vancomycin?

Answer 25

gram + rods and cocci (especially MRS, enterococcus)

Gram - typically resistant

Question 26

Is resistance a concern? what is the mechanism?

Answer 26

MAJOR health human concern

• vancomycin resistant enterococci (VRE)
• MRSA with decrease susceptability to vacomycin

plasmid binding VanA gene changes target binding

Question 27

What is the PK on vancomycin?

Answer 27

poor oral F
limited tissue distribution
excreted via glomerular filtration (renal failure patient)

Question 28

What is the MOA of Polymyxin B?

Answer 28

cationic detergents

- binds to cell membrane and disrupts its tructure

Question 29

What is the SOA of Polymyxin B?

Answer 29

gram - only

Question 30

What are the AE of Polymyxin B?

Answer 30

wide range of toxicity with systemic admin

Question 31

How should Polymyxin be be administered?

Answer 31

topically (otic or opthalamic) or IMM

Question 32

What other use is their for Polymyxin B?

Answer 32

endotoxin binding effects

Question 33

What is Bacitracin (BNPH)? use? formulations?

Answer 33

“topical b-lactam” - same mechanism

use: gram + bacteria

also
- premixes in poultry and swine (growth and prevention of enteritis)

Question 34

What is the MOA, use and PK of Mupirocin? what is the human drug name?

Answer 34

human fromulations

MOA: blocks bacterial protein synthesis

PK: rapidly metabolized after systemic administration
Form: topical (for staph infections), intranasal for MRSA
good penetration into infected tissues

Muricin
USE: pyoderma in dogs

Question 35

What are drugs we should not use in Vet Med?

Answer 35

Linezolid
- last resistance saved for humans

Colistin

• related to polymyxin B
• used in china for swine
• lead to high resistance and zoonotic risk