Farad Withdrawal

FARAD Withdrawal

Overview

FARAD (Food Animal Residue Avoidance Databank) is the federally funded resource for drug withdrawal interval recommendations in food-producing animals. Maintained by UC Davis School of Veterinary Medicine, FARAD provides evidence-based guidance for both FDA-approved label withdrawals and extralabel drug use (ELDU) withdrawal determinations when commercial withdrawal data is unavailable.

What is FARAD?

Definition: Database and consultation service that provides withdrawal interval recommendations to ensure food animal products (meat, milk, eggs, honey, aquaculture) are safe for human consumption.

Regulatory Authority:

• Established under AMDUCA (Animal Medicinal Drug Use Clarification Act)
• Endorsed by FDA CVM, USDA-APHIS, state veterinary boards
• Primary resource for veterinarians determining ELDU withdrawal times
• Non-regulatory (advisory); veterinarian makes final determination

What FARAD Provides:

• Withdrawal time recommendations (in days for meat, hours for milk, days for eggs)
• Pharmacokinetic basis and safety margins
• Relevant literature citations
• Species-specific calculations
• Conservative ("extra-safe") vs. standard margin options
• Written recommendation documentation for veterinary records

Contact Information

Phone Consultation:

• Primary Line: 1-888-873-2723 (1-888-USFARAD)
• Hours: Monday-Friday, 8:00 AM - 4:30 PM Pacific Time
• Wait Time: Typically 24-48 hours for response (urgent cases prioritized)

Email Submission:

• Email: FARAD@ucdavis.edu
• Turnaround: 2-3 business days for written response

Online Database:

• Website: https://www.farad.org
• Search Field: Can query commonly used drugs with pre-calculated withdrawals (convenience lookup)
• Not All Drugs: Limited to most frequently used compounds; custom consultations needed for novel drugs

Fax (legacy):

• Available for formal submission; phone/email preferred

Species Covered by FARAD

Primary (Most Comprehensive Data):

• Beef cattle
• Dairy cattle
• Swine
• Poultry (chickens, turkeys)
• Sheep
• Goats

Secondary (Limited Data Available):

• Horses
• Aquaculture (farmed fish: salmon, catfish, trout)
• Rabbits
• Fur-bearing animals (minks)

Not Covered:

• Wildlife (deer, elk, wild boar - typically no withdrawal recommendations provided)
• Companion animals (dogs, cats) - not food-producing; different regulatory framework

When to Consult FARAD

Mandatory FARAD Consultation:

1. Extralabel Drug Use (ELDU): Drug is being used off-label (species, dose, route, or indication) and NO withdrawal time is on the FDA-approved label
2. Compounded Drug: Compounded formulation has no standard withdrawal data
3. Novel Drug Combination: Multiple drugs given concurrently; unknown interaction on withdrawal time
4. Accidental Exposure: Animal exposed to prohibited substance (e.g., avermectin to dairy cow); need emergency withdrawal guidance

Recommended FARAD Consultation:

• Aminoglycoside use in dairy (complex pharmacokinetics; kidney residue concentration)
• First-use of unfamiliar drug in food animal
• Pediatric/geriatric animals where metabolism differs from standard (very old cattle with renal disease, neonatal animals)
• Suspected drug interaction affecting residue depletion

Not Necessary:

• FDA-approved label withdrawal time is specified (use label without consultation)
• Companion animal drug use (dogs, cats, birds - non-food)
• Human medication used off-label in non-food animals

What FARAD Provides in Recommendation

Standard FARAD Written Recommendation Includes:

1. Header Information:

   • Date of recommendation
   • Consulting veterinarian name and contact
   • Drug name (generic + brand)
   • Species (beef, dairy, swine, etc.)
   • Target animal weight/age (if relevant)

2. Dose & Administration:

   • Specified dose (mg/kg or total dose)
   • Route of administration (PO, IV, IM, intramammary, feed)
   • Frequency (once daily, twice daily, single injection, etc.)
   • Duration of treatment (days)

3. Withdrawal Recommendations:

   • Meat Withdrawal: Number of days between last dose and slaughter/harvest for human food
   • Milk Withdrawal: Number of hours between last dose and milk collection for human consumption
   • Egg Withdrawal: Number of days for egg withdrawal (poultry only)
   • Tissue Specificity: If organ meats have different withdrawal (e.g., liver vs. muscle)

4. Safety Margin Designation:

   • Standard Margin: Based on pharmacokinetic data with typical safety buffer (1.5-2x)
   • Conservative/Extra-Safe Margin: Higher safety buffer (2-5x) recommended for:
     • First-time use of drug
     • High-value animals
     • Immunocompromised animals
     • Renal/hepatic impairment

5. Pharmacokinetic Basis:

   • Summary of half-life, clearance rate, tissue distribution
   • How withdrawal time was calculated
   • Assumptions (normal kidney/liver function, standard species physiology)

6. Literature Citations:

   • Published pharmacokinetic studies
   • Previous FARAD consultations if relevant
   • Manufacturer data if available
   • Why certain literature was used vs. alternative studies

7. Special Considerations:

   • Drug interactions if other medications given concurrently
   • Age/weight effects if non-standard
   • Disease state effects (renal/hepatic impairment = longer withdrawal)
   • Regional/market considerations (some countries stricter than US)

Regulatory Framework: AMDUCA & Withdrawal

AMDUCA Permits Extralabel Drug Use When:

• Veterinarian establishes valid VCPR (client-patient relationship)
• Drug is FDA-approved (for any species or indication)
• No FDA-approved alternative exists or is unsuitable
• Veterinarian determines safe withdrawal interval
• Extra-label use is documented in medical record

Veterinarian Responsibility:

• Final determination of withdrawal time belongs to prescribing veterinarian (not FARAD, not pharmacist)
• FARAD provides evidence-based recommendation; veterinarian may choose more conservative interval if justified
• Withdrawal time must be documented in animal medical record and communicated to client
• Veterinarian liable if withdrawal time is violated (residue in food = public health violation)

Client Responsibility:

• Client (producer) must adhere to withdrawal interval
• Cannot slaughter/milk/egg collect until withdrawal has elapsed
• Client must track withdrawal dates (typically calendar notation, tags on animal pens)
• Violation results in carcass/product condemnation and potential legal action

Common Extralabel Drug Withdrawal Examples

How to Submit a FARAD Request

Telephone Request (Fastest for Emergency):

1. Call 1-888-873-2723
2. Describe animal, disease, drug name/dose/route/frequency
3. Provide species, approximate weight, health status
4. FARAD consultant provides verbal recommendation immediately or within 24 hours
5. Document in medical record

Email/Online Submission:

1. Go to https://www.farad.org
2. Click "Submit a Consultation"
3. Complete form:
   • Your contact information
   • Consulting veterinarian name/license #
   • Animal species, weight, age, health status
   • Drug name (generic + brand), dose, route, frequency, duration
   • Indication (disease/condition being treated)
   • Reason for extralabel use (label not available, unsuitable dose, etc.)
   • Any concurrent medications
4. Submit; FARAD responds via email in 2-3 business days

Written Documentation Requirements:

• VCPR established (client-patient relationship documented)
• Clear justification for extralabel use
• Specific drug + dose + route + frequency + duration
• Target withdrawal product (meat, milk, egg)
• Any comorbidities affecting metabolism

Using FARAD Online Database Search

Searchable Field (Limited Database):

• Drug name (generic or brand): "doxycycline", "amoxicillin", "flunixin"
• Species: "beef cattle", "dairy cattle", "swine", "poultry"
• Pre-calculated withdrawal times for most-used compounds
• NOT a complete database; novel drugs/combinations require consultation

Search Steps:

1. Go to https://www.farad.org
2. Navigate to "Database Search"
3. Enter drug name + species
4. View pre-calculated withdrawal times if available
5. If not found: submit custom consultation

Safety Margin Interpretation

Standard Safety Margin (1.5-2x):

• Withdrawal time = (mean time to residue <tolerance) × 1.5-2
• Suitable for: standard animals, normal renal/liver function, single drug use
• Risk: if pharmacokinetics slightly slower than assumed, residue may remain above tolerance

Conservative/Extra-Safe Margin (2-5x):

• Withdrawal time = (mean time to residue <tolerance) × 2-5
• Suitable for: first-use, high-value animals, immunocompromised, renal/hepatic impairment, critical food safety
• Lower risk of residue violation; longer withdrawal period requires client compliance planning

Example: Drug X residue depletes below tolerance in 10 days in healthy animal.

• Standard margin recommendation: 15 days
• Conservative margin recommendation: 20-25 days
• Veterinarian may choose either based on clinical judgment and client compliance capability

Limitations of FARAD Recommendations

• Pharmacokinetic Assumptions: Based on normal animal; disease (renal failure, hepatic disease) alters clearance (veterinarian may extend withdrawal)
• Tissue Distribution Variation: Some drugs concentrate in specific tissues (kidney, liver); standard calculations may not account for organ-specific withdrawal
• Novel Drug Combinations: FARAD may lack data; may recommend extra-conservative margin or defer to veterinary literature
• Regional Variation: Some countries have different tolerances; FARAD primarily addresses US FDA tolerances
• Limited Data for Exotic Species: Horses, aquaculture, rabbits have fewer pharmacokinetic studies; may recommend longer withdrawal or suggest literature review
• Client Compliance: FARAD recommendation is only as good as producer adherence; veterinarian must verify tracking and enforcement

Integration with Veterinary Practice

Workflow:

1. Treat food animal off-label
2. Call FARAD immediately or within 24 hours
3. Document FARAD recommendation in medical record with date/time of consultation
4. Communicate withdrawal end date to client in writing (calendar, tag on animal pen)
5. Verify at slaughter/milk pickup that withdrawal has elapsed
6. Document final product disposition (sold, held, destroyed if violated)

Medical Record Documentation:

Date: 2024-03-18
Animal: Dairy cow #42, Holstein, 500 kg
Diagnosis: Clinical mastitis
Treatment: Ceftiofur IV 1 g daily × 3 days (ELDU - no label approval for IV)
FARAD Consultation: 888-873-2723, consulted 3/18/2024
FARAD Recommendation: 7 days meat withdrawal, 24 hours milk withdrawal (standard margin)
Withdrawal End Date: 3/25/2024 for meat; 3/19/2024 for milk
Client Notified: Yes, verbally + written instruction sheet

Sources

• FARAD Website: https://www.farad.org
• FARAD Phone: 1-888-873-2723
• AMDUCA Guidance (FDA CVM): https://www.fda.gov/animal-veterinary/guidance-documents
• UC Davis School of Veterinary Medicine: Hosts FARAD
• Plumb's Veterinary Drug Handbook (current edition): Withdrawal time tables
• Approved Animal Drug Products (Green Book): Official label withdrawal times