New warnings on migraine drug - sumatriptan, Imitrex

Healthfacts, Feb, 1995

As is often the case with a heralded new drug, post-marketing experience reveals greater risk of serious drug-related problems than is suggested by the small, short-term studies necessary for approval. The migraine drug sumatriptan (brand name: Imitrex), which was approved in the U.S. in 1993, is no exception. Increased reports of adverse effects has resulted in Glaxo, the manufacturer, providing doctors with new warnings about the drug twice within the past four months (Scrip, 2 September 1994 and 25 November 1994).

In August 1994, doctors were cautioned about deaths caused by cerebrovascular events in patients treated with sumatriptan. But, according to Glaxo's letter, most of these were probably caused by underlying heart problems whose symptoms were mistaken for those of a migraine headache, resulting in the inappropriate prescription of sumatriptan. The drug label now advises doctors to be cautious in diagnosing as a migraine what might be symptoms of stroke or cerebral hemorrhage.

In November 1994, Glaxo also advised doctors that because sumatriptan injections are usually self-administered they should provide this caution to their patients: "For a given attack, if a patient does not respond to the first dose, the diagnosis of migraine should be reconsidered before administration of a second dose."