The FDA has added a boxed warning to the labeling of the antimalarial drug mefloquine, advising of the possibility of neurologic and psychiatric adverse events, the agency announced.
Mefloquine hydrochloride is used for the prevention of malaria caused by Plasmodium falciparum, including chloroquine-resistant strains, and P. vivax, and for the treatment of mild-to-moderate disease.
The drug initially was developed by the U.S. military in the early 1970s, at a time when chloroquine resistance was on the rise, and even during initial testing there were reports of neurologic problems.
Its proprietary formulation, Lariam, is no longer available in the U.S., but generics remain on the market.
The neurologic side effects include dizziness, vertigo, tinnitus, and loss of balance relating to vestibular damage, as well as seizures and insomnia.
Psychiatric adverse events include depression, hallucinations, confusion, paranoia, anxiety, and restlessness.
These events can be particularly difficult to diagnose in children, according to the FDA statement.
In some reported cases, both neurologic and psychiatric symptoms were persistent or permanent, and developed after just one or two doses of the drug in individuals who were otherwise healthy.
A Cochrane review also identified 22 cases of deaths, including five suicides, linked with mefloquine use.
Information about the adverse events will be included in the patient information and wallet card provided with each prescription of mefloquine.
Patients also will be advised to contact their healthcare provider if these symptoms develop, but not to stop taking the medication unless told to do so.
The agency also encouraged clinicians to report any adverse reactions associated with mefloquine to the FDA's MedWatch program, noting that it will continue to evaluate the drug's safety.