The GP took my blood pressure and prescribed Imigran (sumatriptan). On arriving home I had breakfast and took one. Nothing prepared me for what was to follow. I collapsed and came to some seven hours later, able to do very little. Breathing difficulties, a lack of appetite and a feeling of total lethargy followed for the next three days.

After this experience I refused to take any more, preferring to suffer the pain of migraine, which I experience about once a year. J M, Newhaven, East Sussex.

A:As you know from the patient information leaflet you were given with your drug, Imigran, generically known as sumatriptan, is a new migraine drug, called a 5-HT agonist, which supposedly works by reducing the swollen blood vessels around the brain.

It is chemically related to 5-hydroxytryptamine, or serotonin, a chemical in the brain, and was developed after scientists revised their thinking about what causes migraine. Dr Frank Clifford-Rose of the Charing Cross Hospital, who helped coordinate many of the studies of sumatriptan, says that migraine, rather than being initiated by the blood vessels in the brain itself, is now believed to be a biological disease of the nervous system, and that serotonin plays a key role. It has long been known that 5-HT can cause headaches, and experiments have shown that 5-HT is released during migraine attacks.

Glaxo was the first to come up with a drug which was chemically related to 5-HT, but supposed to selectively block the receptors for this hormone, causing the blood vessels in the brain to constrict without affecting what could be as many as 15 other 5-HT receptors, which affect blood clotting, activity in the lungs and the gastrointestinal system in the central nervous system.

In 1991, Glaxo enthusiastically launched sumatriptan as "a revolutionary acute therapy in migraine" after a number of studies showed highly promising results in patients injected with the drug under the skin (the faster route) or given it in tablets.

In two studies testing sumatriptan against a placebo in a total of 1600

patients, within two hours, 81-86 per cent of patients had their headaches disappear or lessen to the point of being mild (N Engl J Med, 1991; 325: 316-21 and JAMA, 1991; 265: 2831-5).

In the wake of a great deal of noisy fanfare over what was thought to be one of the first real breakthroughs for migraine, medicine has begun to retrench, now that the reports are flooding in demonstrating that patients taking this drug may be trading one health problem for another or, indeed, making the problem worse.

The latest studies show that at least 5 per cent of users of sumatriptan experience chest pain. Because the drug works on blood vessels, it has always been assumed that the chest pain had to do with the heart. But a new study (The Lancet, 8 October 1994) shows that the pain may start in the esophagus (the canal from your mouth to your stomach). A double-blind study of 24 volunteers randomly injected with either sumatriptan or saline found that there were no electrocardiogram changes. However, studies of the esophagus showed that contractions of the esophagus were significantly increased by sumatriptan.

Five of the subjects (21 per cent) developed chest pain, lasting from two to 45 minutes, although there seemed to be no relation in time between onset of the pain and the abnormal recordings of movement of the esophagus.