FDA warns veterinarians of risks associated with altrenogest exposure

Shutterstock.comThe FDA is alerting veterinary professionals that a synthetic progesterone product often used in horses and pigs may cause reproductive disorders in people exposed to the drug. Some of these adverse effects have occurred in teenage girls, the agency reports in a media release.

Altrenogest is a progestin used to suppress estrus in mares and to synchronize estrus in gilts (young female pigs). It's marketed under several brand names, including the equine products Regumate, Ovamed and Altren and the swine products Matrix, Chronomate and Swinemate. The equine products are available via veterinary prescription and can be administered directly on the base of the mare's tongue or on the mare's feed. The swine products are available over-the-counter and are administered with feed. These liquid products may be administered to the animals on a daily basis for long periods of time.

The FDA has received reports of adverse effects involving altrenogest exposure in 137 people over the last 30 years-115 women and 22 men. Eighteen of the women were teenage girls, some as young as 14 years old. Reproductive system issues have included abnormal or absent menstrual cycles in women and, in men, decreased libido, the FDA states. Headaches, fever, abdominal pain, nausea, diarrhea, vomiting and rash have also been reported.

Most people were exposed when the drug contacted their skin, although some exposures occurred when people who did not administer the drug touched product residue on barn surfaces, equipment or treated animals, the FDA says. Most of the reports involved the product Regumate and the rest involved Matrix, but generic altrenogest products are used in the same manner and on the same animal populations, so they have the same risk for adverse events, the agency warns.

The labeling for all altrenogest products includes warnings against human exposure as the hormone is readily absorbed through intact skin, the FDA says. People who should not handle altrenogest products include:

Women who are or suspect they are pregnant

Anyone with thrombophlebitis or thromboembolic disorders or a history of these problems

Anyone with cerebral-vascular or coronary-artery disease

Women with known or suspected carcinoma of the breast

People with known or suspected estrogen-dependent neoplasia

Women with unexplained vaginal bleeding

People with benign or malignant tumors that developed during the use of oral contraceptives or other estrogen-containing products

Anyone with liver dysfunction or disease.

Product labeling directs the use of impermeable, nonporous protective gloves when handling these drug products.

The FDA has been in contact with Merck, which markets Regumate and Matrix, to discuss ways the labeling and packaging of these products could be modified to enhance safety to the user. Any changes to the labeling of these pioneer products must, by law, be applied to any generic products. The agency has issued a warning letter to Bimeda, which markets Ovamed, a generic altrenogest equine product, because an advertisement for the product did not include important risk information associated with the product, it says.

The FDA continues to monitor reports of adverse drug events in people exposed to altrenogest products. Veterinary professionals, horse owners, and operators and employees of swine and equine facilities are encouraged to report adverse drug events to product manufacturers, who in turn are required to report this information to the FDA.