Drug Residues

Question 1

What does ‘adulterated’ mean in food safety?

Answer 1

• Any carcass, part therof, meat or meat food product under one or more of the following circumstances
  
  • If it bears or contains any poisons or deleterious substance which may render it injurious to health
  • If it bears or contains (by reason of administration of any substance to the live animal or otherwise) any added poisonous or added deleterious substance which may , in the judgment of the Secretary, make such article unfit for human food

Question 2

What does ‘NOEL’ mean in food safety?

Answer 2

• No Observable Effect Level
• highest dose of drug that does not produce adverse effects in traditional toxicology studies

Question 3

What does ‘ADI’ mean in food safety?

Answer 3

• Acceptable Daily Intake
• Reflects uncertainty associated with the extrapolation of data from laboratory animal studies to humans and the variability in sensitivity among humans to the new drug
• It is a NOEL with an additional safety factor

Question 4

What is the ‘safe concentration’ in food safety?

Answer 4

• Amount of total residue of a drug that can be consumed from all edible tissues every day for the lifetime of a human without exposing the consumer to residues in excess of the ADI

Question 5

What is Tolerance in Food safety?

Answer 5

• Maximum concentration of a marker residue that can legally remain in the target tissue
  
  • Target tissue and marker residue are selected so that absence of residue would confirm that each edible tissue is at or below the safe concentration
  • Target tissue and maker residue is what will be tested at slaughter using the regulatory method

Question 6

What is the ‘target tissue’?

Answer 6

• edible tissue that will be monitored at slaughter

Question 7

what is a ‘marker residue’?

Answer 7

• residue whose concentration is in known relationship to total residues

Question 8

What is the ‘withdrawal period’ / ‘milk discard period’?

Answer 8

• Interval between the time of the last dose and when the animal / product can be consumed
  
  • Calculated using statistical tolerance limit
    
    • 99th percentile tolerance with 95% confidence
    • protects producer and consumer - tissue or milk samples collected at the proper withdrawal time will be below tolerance
• Withdral times are rounded up to the next day or milking

Question 9

What organizations monitor residues?

Answer 9

• USDA:
  
  • collection of animal products at slaughter
  • Testing of animal products
  • Results are published annually in USDA “Red Book”
• FDA:
  
  • Authority for on-farm enforcement of violative residues

Question 10

What is ‘Tier 1 sampling’?

Answer 10

• Random, scheduled sampling / “programmatic”

Question 11

What is ‘Tier 2 Sampling’?

Answer 11

• Inspector - generated sampling
  
  • Antemortem, postmortem or herd history that indicate an increased risk of violative residues
    
    • Mastitis
    • Metritis
    • Surgical devices (sutures, toggle, etc)
    • Injection sites
      
      • injection sites not ‘target tissue’ but indicate a history of pharmaceutical use
    • Pneumonia / Pleuritis / Pericarditis / Endocarditis
    • Septicemia
    • Cellulitis

Question 12

What residues are most common in dairy products?

Answer 12

• Desfuroylceftiofur
• Penicillin
• Sulfadimethoxine
• Flunixin
• Ampicillin
• Sulfamethazine
• Meloxicam

Question 13

What residues are most common in Bob Veal?

Answer 13

• Neomycin
• Flunixin
• Sulfadimethoxine
• Penicillin
• Sulfamethoxazole

Question 14

What residues are common in Non-formula Fed Veal?

Answer 14

• Tilmicosin
• Florfenicol

Question 15

What residues are common in beef catltle?

Answer 15

Desfuroyleftiofur

Question 16

What are the consequences for residue violations?

Answer 16

• Investigation by FDA / FDA-cooperating state agency
  
  • Listing on “Repeat Violator List”
• Warning Letters
• Injunctions

Question 17

What issues does the FDA commonly cite producers for?

Answer 17

• Failure to maintain adequate treatment records and identify treated animals
• ELDU outside of the context of a VCPR
  
  • Inadequate withdrawal time - indication of extralabel dose / route
  • Use of drugs prohibited for that production class

Question 18

What issues does the FDA commonly cite veterinarians for?

Answer 18

• Failure to provide specific labeling requirements or directions for use on an ELDU prescription
• Failure to establish a substantial withdrawal period for ELDU
• Extralabel use of sulfadimethoxine / phynylbutazone in lactating dairy cows
• ELDU use of ceftiofur crystalline free acid
• Failure to take appropriate measures to assure that withdrawal period is met
• Failure to institute procedures that assure the identity of treated animals is carefully maintained

Question 19

What is a VCPR?

Answer 19

• Veterinarian
  
  • Assumes responsibility for clinical judgments
  • Sufficient knowledge of the patient to initiate a preliminary diagnosis
  • Readily available for follow-up
  • Provides oversight of treatment, compliance and outcome
  • Maintains patient records
• Client
  
  • Agrees to follow instruction of the veterinarian

Question 20

What information should be included in Treatment Protocols?

Answer 20

• Case Definition
  
  • Criteria trigger drug administration
• Regimen
  
  • Which drug? How much? Which route? How often? Duration?
• Records
  
  • Who administered? When? to which animals?
• Withdrawal period - Meat and Milk
• Treatment failure definition
  
  • When do we decide the treatment didn’t work? What is the next treatment ot be administered? When is veterinary diagnosis/intervention warranted?
• Salvage slaughter vs euthanasia