Migraine prevention is a major concern for many of us, and we're always looking for more options. One option that more and more Migraineurs are investigating is Botox, botulinum toxin Type A.

For several years now, researchers in several countries have been conducting clinical trials to investigate the effectiveness of Botox injections in the prevention of Migraines and headaches. Friday, it was announced that Botox has been licensed by the MHRA in the UK for the prevention of Migraine in adults who have chronic Migraine. In this case, chronic Migraine was defined as headaches on at least 15 days per month of which at least 8 days are Migraine. This is the first license worldwide of Botox(R) for this indication, and is also the first prophylactic (preventative) treatment to receive a specific license for patients with chronic Migraine.

Scott Whitcup, M.D., Allergan's Executive Vice President, Research and Development and Chief Scientific Officer, stated:

"There is an unmet need for effective and well-tolerated therapies specifically designed and studied for the prophylaxis of headache in chronic Migraine. The authorisation of Botox(R) marks an evolution in medical care for the prevention of headache in adults with chronic Migraine. It is also a significant milestone in the history of Botox(R) and Allergan is proud to advance novel treatments in the field of neurology through our neurosciences research programme."²

This approval was based largely on the results of the PREEMPT (Phase III Research Evaluating Migraine Prophylaxis Therapy) clinical trial. PREEMPT is the largest clinical trial in chronic Migraine and consists of two phase III clinical trials involving 1,384 adults. Patients were eligible for the study if they had a history of Migraine and experienced 15 or more headache days of which at least 50% were Migraine or probable Migraine during the 28 day baseline period. In a pooled assessment, two thirds of the patients had previously been treated with at least one other headache prophylactic medication and nearly two thirds of the patients were overusing acute medications. During the 28-day baseline period, patients reported suffering from an average of 19.9 headache days (headache for four or more hours in any calendar day), of which an average of 19.1 were Migraine/probable Migraine days (Migraine headache on four or more hours in any calendar day).

At the end of the 28-day baseline period, patients were randomized to receive either 155 - 195 units of Botox(R) administered as 31 injections (155 units) into seven specific head and neck muscle with an additional up to eight injections (up to 40 units) into three of these muscles that could be administered in a 'follow the pain' strategy, or placebo. Patients received two injection cycles in a 24-week double-blind phase and then three injection cycles in a 32 week open label phase.

• At baseline, patients in the Botox(R) treatment group had an average of 19.1 days with Migraine. Patients in the placebo treated group had an average of 18.9 days with Migraine. By week 24 following treatment, Botox(R) treated patients averaged 8.2 fewer Migraine days, which was significantly greater than the change from baseline observed in placebo treated patients (6.2 days), p<0.001
• Patients treated with Botox(R) experienced significantly fewer headache days compared to those patients treated with placebo (47.1% of Botox^(R) treated patients compared to 35.1% of placebo treated patients achieved greater-than or equal to 50% reduction from baseline in the number of headache days at the week 24 primary timepoint, p<0.001)
• Following the open label phase of the trial (week 56), nearly 70% of Botox(R) treated patients experienced greater-than or equal to 50% reduction from baseline in Migraine days
• Patients treated with Botox(R) had significant improvement from baseline in their quality of life scores (MSQ scores) and in the amount of headache related disability (HIT6 scores) compared with those on placebo, indicating significant improvement in patients functioning, vitality, psychological distress, and overall quality of life

Throughout the PREEMPT trials, including the open label phase, patients received up to 5 courses of treatment with Botox(R) every 12 weeks. Most adverse events reported in the trials were mild to moderate and resolved without further problems. The treatment was generally well tolerated and the discontinuation rate was low in both treatment arms; 3.8% in the Botox(R) treated arm and 1.2% in the placebo arm⁴.