PHILADELPHIA – The monoamine oxidase inhibitor isocarboxazid may be an effective migraine preventive as well, Dr. Bruce Corser reported in a poster presented at the International Headache Congress.
Although the open-label trial was small, with just 14 patients, all of those who completed it showed a significant decrease in migraine frequency over 20 weeks, said Dr. Corser, the medical director of Community Research, Cincinnati.
Isocarboxazid is approved for the treatment of depression. “The efficacy of antidepressants and other serotonin-modulating drugs in the treatment of migraine has suggested that monoaminergic pathways are involved in the etiology of migraine,” Dr. Corser wrote. “In addition, a recent study has identified an association between genetic polymorphisms of MAO-A and migraine.”
Dr. Corser and his colleagues included 14 patients (mean age 44 years) who had a diagnosis of migraine and a history of 3-12 migraine headaches per month for the 3 months preceding recruitment. The patients were not allowed concomitant use of antidepressants or other common anti-migraine drugs.
Isocarboxazid was started at 20 mg/day and increased as needed and tolerated to a maximum of 60 mg/day. Most of the patients tolerated a maximum dose of 20-40 mg/day.
However, adverse effects were common and caused five patients to discontinue the trial–one each for insomnia, irritability/anxiety, mood swings/fatigue, anorgasmia, and fatigue. Three other patients reported adverse events as well (fatigue, insomnia, and nosebleed), but they completed the trial.
A total of seven patients completed the final follow-up.
At baseline, patients reported an average of five migraines a month. By week 8, there was a significant reduction in frequency. By week 20, the average frequency per month was less than one.
All of the patients who completed the trial were considered responders by week 16–that is, they experienced at least a 50% decrease in migraine frequency, Dr. Corser and his colleagues reported at the meeting, which was sponsored by the International Headache Society and the American Headache Society.
“In this trial, isocarboxazid showed very robust clinical efficacy in the prophylactic treatment of migraine attack,” Dr. Corser wrote.
In addition to affecting monoaminergic neurotransmission, the drug's effect on blood pressure and vascular tone might add to its benefit in migraine, he added.
The trial was funded by Validus Pharmaceuticals of Parsippany, N.J., and Oxford Pharmaceutical Services of West Totowa, N.J.