Download Chapter 2 - Veterinary Drug Development and Control

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