PRODUCTS THAT ARE CURRENTLY AVAILABLE- AN OVERVIEW

Edward J. Robb, Pfizer Animal Health

Antimicrobials are regulated in the United States by the Center for Veterinary Medicine (CVM) a division within the Food and Drug Administration (FDA). Antimicrobials are commercially available based on their successful review for safety, efficacy and quality to producers for Over The Counter (OTC) sales or through veterinarians as prescription products. Approvals are for the treatment, control and prevention of a variety of bacterial pathogens or for the improvement of performance (weight gain and feed efficiency). An approved drug also know as a NADA (New Animal Drug Application) is required for commercialization. Approvals are by species and sub-class within species. For example, separate approvals are needed for a claim in beef and lactating cattle. Within each species or sub species approval, separate indications or label claims are provided based on the agency's review of the data from a sponsor. Similarly each formulation is separately reviewed and approved.

There are numerous methods that can provide an overview of currently available antimicrobial products. This review will define the diversity, or lack of, for antimicrobial chemical classes approved for livestock. The number of approved antimicrobial compounds within each species or sub class and the number of compounds unique to veterinary medicine will be summarized.

The sources of data used in this census include the Vetgram Database within FARAD (Food Animal Residue Avoidance Database) accessed via farad.org. Numerous listings within the Vetgram database were checked against the list of approved NADA as accessed via the CVM website and the 2002 Feed Additive Compendium. Based on this listing, antimicrobials were classified into twelve chemical classes using the NCCLS (National Committee For Clinical Laboratory Standards)- Cumulative Antimicrobial Susceptibility Test Data- Approved Guideline May 2002.

For therapeutic antimicrobials in beef cattle, 9/12 classes are available representing 17 chemical actives, nine of which are used only in veterinary medicine. For lactating dairy cattle 5/12 classes are available representing nine chemical actives two of which are veterinary specific. Intamammary approvals provide for 6/12 classes, nine chemical actives, four of which are veterinary specific. For pre ruminant calves, used in veal production, only two classes and three actives are approved. In swine 11/12 classes are approved representing 15 therapeutic actives with eight distinct to veterinary use. In sheep only 5/12 classes are available representing six therapeutic actives and in goats 2/12 classes are approved representing two therapeutic actives.

This census provides a perspective on the diversity of available therapeutic antimicrobials for livestock. This review does not support or contrast any particular point of view or hypothesis but provides a perspective for discussion. Diversity of antimicrobial chemical classes, the number or diversity of therapeutic actives within each class and the number of veterinary specific antimicrobials by species may provide insight pertaining to the prevalence of target pathogen, commensial and zoonotic bacterial resistance detected in livestock.