Veterinary drugs and residues Flashcards by awesome possum

What can chloramphenicol cause?

aplastic anemia

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what can diehtylstilbsetrol cause?

bone marrow toxicity

carcinogen

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What can metronidazole cause?

carinogen

teratogen

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what can nitrofurazone cause

carcinogen

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what can phenylbutasone cause?

blood dyscrasias

carcinogen

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what can sulfonamides cause?

hypersensitivity

thyroid tumors

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What can penicillin cause?

hypersensitivity

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What are 4 issues with antimicobial use in food animals?

resistance in pathogens
resistence in commensal bacteria
changes in food animal flora (more enteric pathogens)
effect of drug residues on human enteric flora

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What was the issue with diclofenac?

it killed vultures. was cheap and used for cattle that are not slaughtered (NSAID). vultures are uniquely suscpetible

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Who approves drugs for veterinary use?

Health Canada
Health products and food branch
veterinary drugs directorate

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Does the veterinary drugs directorate regulate drug use?

no. but performs human health risk assessments?

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What does the CFIA do with respect ti drugs?

tests drug residues in food

2. approves biologics (vaccines, antibodies etc)

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What are 6 pre-market steps in approval of vet drugs?

human safety
clinical efficacy
safety in intended species
safety to the environmetn
manufacturing and quality control!
labelling

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What are subchronic toxicity studies?

2 species of lab animals used (rodent and non-rodent)
drug administered orally every day) 3-12 months
low, medium and high dose groups
minimum 2 animals (10 of each sex) per group

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What are chronic toxicity studies?

like subchornic but >12 months

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What are examples of special studies

carcinogenicity tests
reproductive tests
teratogenicity tests
genetic toxicity tests
(others: immunotoxicity, neurotoxicity, endocrine changes)

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What are three studies for human safety testing?

subchronic
chronic
special
tests

What are three studies for human safety testing?

subchronic
chronic
special
tests

What does human safety (microbiology) evaluate?

spectrum of activity
antimicrobial resistance
effect on target animal gut flora
effects on human gut flora
impact on human medicine

What are three aspects of human safety testing?

toxicology and pharmacology
microbiology
drug residues and metabolism

What aspects of spectrum of activity of a drug are considered?

activity to

target animal pathogens
food-borne pathogens
commensal bacteria

What aspects of antimicrobial resistance are examined in new drugs?

mechanism of AMR
mechanism of AMR transfer
rate of AMR development
cross resistance to other antimicrobials

What affects on animal gut flora are evaluated?

if zoonotic pathogens in gut increase
if there are changes in fecal shedding
(changes usually transient)

What is the microbiological acceptable daily intake?

the concentration of drug in food residues that is required to cause changes in the gut flora (human)

What is the acceptable daily intake?

the amount of drug that can be consumed by a human over a lifetime with no adverse effects all drug residues in food (parent compond + metabolites must result in human intake

How is the ADI (acceptable daily intake) determined?

1. toxicology and microbiology data

What is NOEL

No observable effect level (NOEL)

What is NOEL

No observable effect level (NOEL)

what is the no observable effect level (NOEL)

highest dose in the most susceptible species that does not cause any adverse effects (rabbits or rats)

How do you calculate ADI

NOEL divided by a safety factor (usually 100)--10 for intraspecies variability, 10 for interspecies variability

What is microbial ADI?

for antimicrobial only | the lowest concentration of drug that can cause changes in the human gut flora

What is the maximum residue limit?

determines how much drug residue is allowed in food

How is the total residue limit determined?

total residue limit=ADI/food consumption factor

What is the maximum residue limit?

the maximum amount of drug MARKER RESIDUE allowed in tissue

What is the maximum residue limit based on?

based on a ratio of the marker residue to the total residue limit

What is the maximum residue limit based on?

based on a ratio of the marker residue to the total residue limit

What is a withdrawal period

1. period of time from last treatment until an animal can be slaughtered/milk/eggs used for consumption

What is the withdrawal period determined to be?

amount of time for the marker residue coencentration in the slowest animals treated with that drug to fall below the maximum residue limit

What is an issue with the withdrawal period?

have to follow the label!

What might make a carcass suspect?

1. injection site lesions | 2. evidence of pathology or illness

Who determines if the processing plant will take the milk?

processing plant and they can have different levels-even if the residue is below the MRI is may not be accepted

what are some factors that ensure that drugs are very safe?

1. extensive testing 2. 100x safety factor 3. very high food consumption assumed 4. withdrawal periods are based on residues from slowest depleting animals