An unapproved clenbuterol product associated with two horse deaths in Louisiana has prompted the Food and Drug Administration to remind veterinarians and horse owners that no generic versions of the drug are approved for use in animals.

The unapproved product is labeled Clenbuterol HCl, according to a statement issued Nov. 24 by the FDA Center for Veterinary Medicine. The agency has confirmed at least two deaths associated with the "super potent" product at Louisiana State University's veterinary hospital, and an investigation is under way, added an FDA spokesperson.

Three ill horses recently treated at the veterinary hospital all tested positive for clenbuterol, but only one had very high levels of the drug in its system, said Dr. Rebecca S. McConnico, an assistant professor of veterinary medicine at the university. Two of the horses were euthanized, and one recovered, said Dr. McConnico, who has heard unconfirmed reports of three additional clenbuterol-related fatalities in Louisiana.

Ventipulmin, manufactured by the Missouri-based Boehringer Ingelheim Vetmedica Inc., is one of just two prescription clenbuterol medications approved by the FDA as safe and effective for use in horses. Boehringer Ingelheim also makes Aeropulmin, an approved private-label clenbuterol product for distributor customers.

Horse owners and veterinarians aware of horse injuries or deaths that may have resulted from Clenbuterol HCl are urged to contact the FDA office in their area. Following is a link to a listing of FDA consumer complaint coordinators: http://www.fda.gov/opacom/backgrounders/complain.html.

For years, the FDA has been concerned about the availability of illegal clenbuterol formulations, produced as "compounded" drug products. Compounding is permitted by the Animal Medicinal Drug Use Clarification Act only under limited circumstances.