© 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.

Fundamentals of Pharmacology for Veterinary Technicians

Chapter 2

Veterinary Drug Development

and Control

© 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.

Stages of Veterinary Drug Development

• In the United States, new veterinary drugs must go through a series of tests mandated by the FDA

• There are four major steps in drug development:– Synthesis/discovery of a new drug compound– Safety/effectiveness evaluation– Submission and review of the New Animal

Drug Application (NADA)– Postmarketing surveillance stage

© 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.

Synthesis/Discovery of a New Drug Compound

• Potential therapeutic agents must go through a series of tests

Step 1:• Preliminary studies: determine the

intended effect and possible toxic side effects

• May include computer modeling, testing in lab media, or testing on bacteria or fungi

© 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.

Synthesis/Discovery of a New Drug Compound

Step 2:• Preclinical studies: determine a drug’s

safety and effectiveness– Short-term and long-term tests– Check for immediate drug reactions, organ

damage, reproductive effects, carcinogenicity, and teratogenicity

© 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.

Synthesis/Discovery of a New Drug Compound

Step 3:• Submission and review of the New

Animal Drug Application (NADA)– Submit Investigational New Animal Drug

(INAD) application for the drug to the FDA– Submit Experimental Use Permit (EUP) for

pesticide to the EPA– Submit application for biologics to the

APHIS division of the USDA

© 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.

Synthesis/Discovery of a New Drug Compound

Step 3 (cont.):• Submission and review of the New Animal

Drug Application (NADA)– If application is approved, clinical trials

proceed– Clinical trials are done on target species– Satisfactory clinical trial results allow

scientists to file a New Animal Drug Application (NADA) with the FDA, EPA, or USDA

– Approval and license are granted for successful drugs

© 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.

Synthesis/Discovery of a New Drug Compound

Step 4:• Postmarketing surveillance stage

– The drug company and the government monitor the product as long as the drug is manufactured

– This monitoring ensures product safety and efficacy

© 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.

Effective and Lethal Doses

• Effective dose: the amount of the test drug that causes a defined effect in 50% of the animals that receive it– ED50

• Lethal dose: the amount of the test drug that kills 50% of the animals that receive it– LD50

© 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.

Therapeutic Index

• Therapeutic index is the drug dosage or dose that produces the desired effect with minimal or no signs of toxicity– Also called the margin of safety– Determined by comparing the lethal dose and

effective dose of the drug

– LD50 ÷ ED50

– A wide therapeutic index means that the drug can produce its desired effect without approaching toxicity

© 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.

Tests That New Drugs Go Through

• Systems-oriented screening

• Evaluation of long-term effects

• Evaluation of reproductive effects, carcinogenicity, and teratogenicity

© 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.

Drug Marketing Systems

• Direct marketing: drug is purchased directly from the company that makes it

• Distributors or wholesalers: drug is purchased from the manufacturing company and resold to veterinarians

• Generic companies: sell drugs that are no longer under patent protection