In patients with chronic migraine, a daily dose of topiramate (Topamax) is reasonably well tolerated and reduces the number of headaches per month, even in patients who are overusing pain medications, a new study shows.

These findings suggest that the current guidelines recommending that migraine patients who are overusing pain medications need to withdraw from these drugs may be incorrect, report Dr. Peter J. Goadsby, of the Institute of Neurology, London, and colleagues in the medical journal Cephalagia. The overuse of pain medication can also lead to more migraines.

In the study, patients between 18 to 65 years with chronic migraine - defined as 15 or more migraine days per month for 3 or more months and 12 or more migraine days during the 4-week initial phase of the study - were randomly allocated to receive topiramate, a drug approved for the treatment of seizures, or to a placebo for 16 weeks.

At the start of the trial, the average number of migraine days per month was 15.5 in the topiramate group and 16.4 in the placebo group.

More than three quarters of the subjects who met diagnostic criteria for medication overuse were taking ergotamine, triptans, opioids, or a combination of analgesics 10 or more days per month, or taking simple analgesics for 15 days or more per month.

Topiramate was gradually increased by 25-milligram increments weekly to a target dose of 100 mg/day. The doses ranged from 50 to 200 mg/day according to individual needs. Thirty-two patients received topiramate at an average dose of 100 mg/day and 27 patients received placebo.

Goadsby’s team found that topiramate significantly reduced the average number of monthly migraine days by 3.5, compared with an increase of 0.2 days with placebo.

The Migraine Disability Assessment scores improved with topiramate compared with placebo as well.

Adverse effects that emerged during treatment were reported by 75 percent of topiramate-treated patients and 37 percent of placebo-treated patients.

The most topiramate side effects were paraesthesia, the sensation of tingling, pricking, or numbness of the skin with no apparent, also described as a feeling of “pins and needles.” The feeling of having a foot “fall asleep” was reported by 53 percent of patients and nausea reported by 9 percent. The rates of dizziness, indigestion, fatigue, anorexia, and disturbance in attention were each 6 percent with topiramate treatment.

Goadsby and colleagues note that “patients with chronic migraine and medication overuse are common in referral practice, highly disabled, and burdensome to society. We saw a clear effect that was present in the subgroup of patients with medication overuse.”

Goadsby added in an e-mail to Reuters Health: “This study highlights the fact that patients with chronic migraine are treatable and, very surprising to us, that even patients with medication overuse may be treatable by standard migraine preventives before medicine withdrawal. The challenge to us going forward is to identify these patients so we can offer them effective therapies.”

SOURCE: Cephalagia, July 2007.