ANSC 380 Lecture 7: Pharmacology

Pharmacology

  • study of how drugs and chemicals affect living systems

History of Aspirin - Acetylsalicylic acid

  • >3500 yrs ago willow bark used as a painkiller and fever reducer

    • Sumerians and Egyptians

    • Greece and Rome

    • Hippocrates used to treat pain

    • myth vs fact

      • salisin in bark? enough to treat? more concentrated active ingredient, more likely to reduce pain

  • 1763 - antipyretic effects

    • can help reduce fever

  • 1899 - synthesis of Aspirin

  • antipyretic, anti-inflammatory, antiplatelet, chemopreventative (?)

  • one of the most widely used drugs worldwide

Drug Sources

  • chemicals

    • synthesized in labs

  • plants

  • animals

  • minerals

  • recombinant proteins

  • microorganisms

  • drug source examples

    • morphine from poppy

    • digitalis cardiovascular drug from foxglove

    • propyphol contains egg

    • selenium

    • insulin from pig pancreas

Drug Nomenclature

  • chemical name

  • non-proprietary name

  • proprietary name

  • ex.

    • 2-acetoxybenzoic acid

    • aspirin

    • Bufferin, Ecotrin, Empirin

FDA Approval Timeline

  • 2-5 yrs

    • basic science research

  • 1-2 yrs

    • pre clinical testing

  • 5-7 yrs

    • clinical trials

  • 1/2-1 yrs

    • gov approval

Preclinical Trials

  • assess safety and efficacy of drug prior to human testing

    • determine safe starting dose

    • assess potential toxicity

  • in vitro testing

  • in vivo testing

    • 2 or more species of animals

Clinical Trials

  • phase 1

    • initial safety and dosage in healthy volunteers

    • give drug at different dosages

  • phase 2

    • efficacy and safety of drug in larger group

    • have the disease

    • more people than phase 1

  • phase 3

    • confirms efficacy of drug

      • drug vs placebo

    • large

    • randomized

  • phase 4

    • post FDA approval

    • monitoring with safety of drug once it is out in the market

Clinical Trials Gone Poorly

  • termination

  • complications

  • lack of volunteers

    • typically need 100s-1000s of people for sample size

  • cause vs effect

    • disease progression vs drug?

Federal Drug Approval

  • FDA

    • regulate safety and efficacy of human and animal drugs

    • food products from animals are safe for human consumption

      • meat, milk, eggs

    • regulate animal food

    • monitor development of antibiotic resistance in food production animals

    • regulate animal health products and feed additives

    • report adverse reactions and illegal drug use

  • USDA

    • leadership related to agriculture, natural resources, rural development, nutrition

    • approves diagnostics kits, animal vaccines

    • monitors drug residues in food supply

      • random testing

  • EPA

    • human and environmental health

    • regualte environmental safety and efficacy of pesticides in animals

      • ex. f/t prevention

Marketing Channels for Drugs

  • Non-prescription

    • available without restriction

    • feed stores, pet stores

    • ex. dewormers, certain vaccines, vitamins

  • Prescription

    • available by the order of a licensed practitioner to client

      • veterinarian-client-patient relationship (VCPR)

    • ex. all antibiotics, analgesics, heartworm preventatives, hormones, insulin, sedatives, in the past antibiotics but not true anymore

  • Controlled

    • prescription drugs with potential for human abuse

    • DEA registered practitioner prescription

    • records

    • ex. ketamine, diazepam, gabapentin

  • Veterinary Feed Directive

    • nonverbal order of licensed practitioner to clients with VCPR

    • for use in animal feeds, drinking water

  • ex. medically important antibiotics

    • chlortetracycline, sulfamethazine, penicillin, lincomycin, tylosin, florfenicol, etc

  • ex. A cat received Revolution Plus (flea/tick prevention) and started drooling and vomiting after topical application. Which of the following agencies should be alerted of the side effect?

    • EPA (pesticides in animals)

VCPR

  • veterinarian-client-patient-relationship

  • 1. A vet has assumed the responsibility for making medical judgments regarding the helath of the animal(S) and the need for medical treatment, and the client (the owner of the animal or other caretaker) has agreed to follow the instructions of the vet

  • 2. There is sufficient knowledge of the animal by the vet to initiate diagnosis

  • 3. Practicing vet is readily available for follow-up in case of adverse reactions

Veterinary Feed Directive

  • licensed veterinarian

    • used under supervision

  • valid VCPR

  • producer to obtain VFD order from vet and take to supplier

    • writen or electronic

  • expiration date (<6mo)

    • cannot feed past this date

  • copy for VFD kept for 2 hrs

    • producer, feed supplier, records

  • farmer chooses to use medicated feed, farmer and his vet discuss using medicated feed, vet writes VFD so that medicated feed is used correctly (keeps one copy), vet gives 2 copies to farmer, farmer takes copy to feed supplier and purchases medicated feed, feed supplier sells farmer the feed as directed on VFD

Antibiotic resistance

  • Antibiotic resistance in the animal population can affect the human population by eating those animals

Extralabel Drug Use (ELDU)

  • AMDUCA - American Medicinal Drug Use Clarification Act of 1994

  • permits vets to prescribe extralabel use of certain approved animal and human drugs for animals under certain conditions

  • applies to ALL species

  • extralabel: use of an approved drug in a manner not in accordance with the label directions

ELDU Requirements

  • must have a valid VCPR

  • vet must supervise and direct the ELDU

  • only FDA approved drugs

  • prevention, treatment, or control purposes whtn animal health is suffering

    • extralabel used to enhance production is not allowed

Food Animal Production Medicine: ELDU

  • only use when there is NO approved animal drug labeled for use to treat condition in that species

    • exception: vet finds that preparation clinically ineffective

    • only true in food animal

    • diagnose and evaluate condition

    • establish substantially extended withdrawal period

    • supported by science *(FARAD)

    • ID treated as animal maintanied

  • FARAD

    • Food Animal Residue Avoidance DAtabank

    • safe food

    • prevent and mitigate chemical residues in food animal products

ELDU Label Requirements

  • name and address of vet and pharmacy

  • name of drug

  • directions specified by vet species, id of animals

  • Record REquirements

    • identify animals

    • species and number

    • medical conditions

    • name of drug and active ingredient

    • dosage

    • treatment duration

    • specified withdrawal, holding

    • keep records 2 yrs after

Drug Residue

  • milk antibiotic residue testing

  • all bulk milk tankers sampled

  • antibiotics (beta-lactam)

  • if residue is found, dairy farmer fined and milk is disposed

  • meat drug residue

    • antibiotics, pesticides, etc

    • meat, poultry, egg products

    • residue, condemntation, destruction, penalties, legal action, other animal testing

Residue Avoidance

  • not consulting with vet

  • not following label

  • not appropriate withdrawal period

  • poor ID of treated animals

  • not diverting milk from treated cow from bulk tank

  • different route of administration

  • entire drug dose in one spot

  • overdose