Bimectin EUA Allows Cattle Ivermectin Use
The FDA has granted emergency use authorization for the generic ivermectin injection Bimectin to prevent New World screwworm infestations in cattle, making
The FDA issued an emergency use authorization (EUA) for the generic ivermectin injection Bimectin to prevent New World screwworm (NWS) infestations in cattle. The drug may be administered within 24 hours of birth, at castration, or when a wound appears.
Bimectin is the agency’s 14th EUA against NWS, as detections of the flesh-eating parasite rise in Texas. The USDA has confirmed 47 domestic cases of NWS in animals, including 3 dogs. stats
| Species | Cases |
|---|---|
| Domestic animals | 47 |
| Dogs | 3 |
Bimectin is a generic version of Ivomec, which the FDA authorized in February 2026 for NWS prevention in cattle. The authorization applies only to the injectable form and does not cover other dosage forms. It is not authorized for use in lactating dairy cows or in calves that will be processed for veal, and producers must observe a 35-day slaughter withdrawal time to avoid drug residues in the food supply.
The product is available over the counter without a prescription. “By authorizing both generic and pioneer products, the Agency is ensuring producers aren’t dependent on a single manufacturer or product to protect their herds,” said Timothy Schell, PhD, director of the FDA’s Center for Veterinary Medicine.
The FDA did not require new bioequivalence, target animal safety, or human food safety studies for the authorization. The agency grounded its effectiveness determination in Bimectin’s established bioequivalence to Ivomec and in studies conducted with ivermectin injection. squad
Evidence includes four dose confirmation studies conducted in Brazil and Argentina in 1991 and 1992. In those trials, no calves treated with a single 200-mcg/kg dose developed myiasis requiring rescue treatment, while untreated controls developed infestations within the first week of birth or castration.
Published literature from 1993 to 2022 showed variable but supportive results. The agency noted that effectiveness figures differed across studies but collectively supported a reasonable belief that the product may be effective when used as authorized.
According to the FDA’s Freedom of Information document, the known and potential benefits of Bimectin outweigh its known and potential risks. Untreated NWS infestations can be fatal because of tissue damage caused by the larvae.
Bimectin joins a small set of products already cleared against NWS in cattle: a conditionally approved injectable, Dectomax-CA1 (doramectin), and a conditionally approved topical, Exzolt Cattle-CA1 (fluralaner). The FDA determined that neither the conditionally approved injectable nor the conditionally approved topical is an adequate alternative to an over-the-counter generic. The injectable cannot be produced in sufficient quantities to meet the demands of a widescale incursion, while the topical belongs to a different pharmacological class, requires a prescription, and is restricted to cattle 2 months and older.
The EUA will remain in effect until it is revoked or the Secretary of Health and Human Services ends the emergency declaration that allows the FDA to authorize animal drugs for NWS. Bimectin injection is sponsored by Ireland-based Bimeda Animal Health Ltd.
