1. Chapter 2 Veterinary Drug Development and Control
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2. 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
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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
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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
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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
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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
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7. 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
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8. Safety and Effectiveness Evaluation
Special tests
Reproductive affects
Conception, fertilization, pregnancy
Carcinogenicity
Cancer causing
Teratogenicity
Fetal defects in pregnant animals
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Toxicity Evaluation
Conducted on mice
Highest dose that results in tissue and organ damage
Highest dose that results in permanent injury or death
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10. 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
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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
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Additional Testing
Systems-oriented screening
Evaluation of long-term effects
Evaluation of reproductive effects, carcinogenicity, and teratogenicity
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