FDA warns Micotil 300 is dangerous

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An antimicrobial used in cattle and sheep has killed at least 25 people and hurt thousands in 25 years.

Food and Drug Administration officials issued a warning in September to veterinarians, livestock owners, and health care providers that tilmicosin is dangerous and has no antidote.

Micotil 300, an injectable tilmicosin drug, is administered to treat respiratory disease in cattle and sheep. It has been associated with 2,200 reports in the U.S. of adverse events involving human exposure, most of them from accidents, according to FDA information. At least 16 of the 25 deaths associated with Micotil 300 likely were by suicide.

"This drug has been shown to have toxic effects on the human heart," the FDA announcement states. "In some cases of exposure, people required hospitalization and prolonged medical care; some people have died despite receiving medical care."

In a message, FDA spokeswoman Lindsay Dashefsky said the drug's manufacturer, Elanco, has implemented online training and adjusted the product to improve handling, among other changes since the drug was approved in 1992.

In May 2017, the Centers for Disease Control and Prevention's National Institute for Occupational Safety and Health issued recommendations on preventing deaths and injuries from Micotil 300. NIOSH recommends that veterinarians consider prescribing medications without toxic effects on humans, administer Micotil 300 only with appropriate animal restraint, ensure that people administering the drug have the appropriate skill, review safety warnings with clients, and describe to clients what equipment is appropriate for administration.

A NIOSH document indicates that, in humans, Micotil 300 reduces cardiac contractility and causes tachycardia. The drug label includes a note to physicians that the drug may hurt a human heart by blocking calcium channels.

"In dogs, administration of intravenous calcium offset Micotil-induced tachycardia and negative inotropy (decreased contractility)," it states. "Dobutamine partially offset the negative inotropic effects induced by Micotil in dogs. ß-adrenergic antagonists, such as propranolol, exacerbated the negative inotropy of Micotil in dogs. Epinephrine potentiated lethality of Micotil in pigs. This antibiotic persists in tissues for several days."

The CDC NIOSH recommendations are available as a PDF document at http://jav.ma/nioshmicotil.