chapter 2 veterinary drug development and control copyright © 2011 delmar, cengage learning

Chapter 2

Veterinary Drug Development

and Control

Copyright © 2011 Delmar, Cengage Learning

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


Stage One

• 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


Stage Two

• 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

– Submit Investigational New Animal Drug (INAD) application for the drug to the FDA

– Clinical trials begin once application is approved


Stage Three

– 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


Stage Four

• 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


Safety and Effectiveness Evaluation

• Short-term tests – hours following a test dose

– check the animal for obvious adverse reactions

• Long-term tests – typically run for 3 to 24 months of repeated dosing

– check the animal’s various organ systems for toxicity

damage


Safety and Effectiveness Evaluation

• Special tests– Reproductive affects

• Conception, fertilization, pregnancy

– Carcinogenicity• Cancer causing

– Teratogenicity • Fetal defects in pregnant animals


Toxicity Evaluation

• Conducted on mice• Highest dose that results in tissue and organ

damage• Highest dose that results in permanent injury

or death


Effective and Lethal Dose

• 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


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


Additional Testing

• Systems-oriented screening

• Evaluation of long-term effects

• Evaluation of reproductive effects, carcinogenicity, and teratogenicity


chapter 2 veterinary drug development and control copyright © 2011 delmar, cengage learning

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