Regulatory framework for the availability and use of animal drugs in the United States.

The goal of this article is to help practitioners understand the regulatory framework and basis for the approval of new animal drugs, the terminology and specific meaning of terms related to drug approval, and the marketing and use of veterinary drugs in companion animal practice. Understanding the differences between approved versus unapproved drugs and their use helps practitioners make the appropriate clinical decisions on their patients' treatment. Only when buying approved animal drugs can clinicians be assured of product safety, effectiveness, and manufacturing to the strict standards for quality, purity, and potency, as well as truthful and complete labeling.

Regulatory considerations for the approval of analgesic drugs for cattle in the United States.

Continuous life-cycle management of veterinary drugs by the Food and Drug Administration Center for Veterinary Medicine (CVM) ensures that safe and effective approved animal drugs are available for use in the United States. This article summarizes basic requirements for the approval of new animal drugs, with a specific focus on the approval of analgesic drugs for use in cattle. CVM encourages drug companies to use innovative approaches to demonstrate the effectiveness of analgesic drugs for cattle.

Considerations for extrapolating in vivo bioequivalence data across species and routes.

The purpose of this article is to discuss the numerous species-specific and route-specific factors that can influence the peak and extent of exposure of an active pharmaceutical ingredient as they relate to the demonstration of bioequivalence between veterinary drug products (test and reference formulations). Evaluation of potential circumstances when species-to-species or route-to-route extrapolations of bioequivalence data could be considered is provided, together with suggestions for alternative statistical analysis. It is concluded that further research is much needed in this area to establish an appropriate scientific basis for across-species and across-route comparisons.

Should licking behavior be considered in the bioavailability evaluation of transdermal products?

Antiparasitic drugs, and especially macrocyclic lactones (MLs), are often formulated as pour-on products because of their ease of administration, convenience, and reduction of stress in treated animals. However, because of self- and allo-grooming, much of a drug administered transdermally may be systemically absorbed via the oral route, creating highly variable pharmacokinetic and pharmacodynamic response in treated (and untreated) animals. Testing bioequivalence (BE) of pour-on drugs in cattle under laboratory conditions (with restricted licking) ignores a major factor of drug disposition of these drugs and thus fails to predict therapeutic equivalence in the target population under clinical conditions of use.

Safety of antibiotic drugs in food animals: comparison of findings from preapproval studies and postapproval experience in the United States with safety information in published literature.

Antibiotics are among the most widely prescribed drugs and are generally considered safe for the target species. However, their use has been associated with various adverse toxic effects in target animals, such as allergic reactions, gastrointestinal signs, cardiovascular effects, hypoglycemia, hepatic/renal toxicity, thrombocytopenia, and anaphylaxis. This article provides a qualitative summary of the adverse events observed in target animals during the evaluation of antibiotics by the Food and Drug Administration during both preapproval and postapproval periods.