Botulinum toxin type A, celebrated by seekers of eternal youthfulness for its ability to temporarily smooth wrinkles, also might provide relief of chronic daily migraines, Brazilian investigators suggest.
A single treatment session consisting of botulinum toxin type A (OnabotulinumtoxinA, BTX-A) injections to 15 sites on the head was comparable to daily oral dosing of the tricyclic antidepressant (TCA) amitriptyline for preventing chronic daily migraine over 90 days, reported Elza Magalhães and her colleagues from the Federal University of Bahia, Brazil (Clin. Neurol. Neurosurg. 2010 April 18; [doi:10.1016/j.clineuro.2010.02.004]).
Both BTX-A injections and amitriptyline reduced the number of pain days by at least 50% in more than two-thirds of patients with chronic daily migraine, and each treatment cut the intensity of patient-rated pain approximately in half, according to the investigators.
“Considering the clinical benefits and the lack of undesirable side effects, such as weight gain and constipation, we argue that BTX-A should be considered for use in patients with chronic headaches as an alternative therapy or should be considered for use in patients who have contraindications for the use of other classes of drugs,” Ms. Magalhães and her coauthors wrote.
They enrolled 72 adults (aged 18 to 56 years) with chronic daily migraine according to International Classification of Headache Disorders-II criteria, and randomly assigned them to receive either BTX-A in a total dose of 250 units (35 patients), or 25 mg or 50 mg of amitriptyline daily (37 patients). Patients on the oral drug initially were given the 25-mg dose, and were titrated upward to the 50 mg dose if they did not have remission of symptoms from the lower dose at 30 days.
Patients assigned to BTX-A received 15 injections into pre-determined sites around the head. The injection sites included areas over sensitive innervations, including the trigeminal, C2, and C3 nerves.
Patients in both treatment groups were evaluated monthly for pain intensity, number of pain days, number of drug doses for pain, and side effects.
In all, 72% of patients treated with amitriptyline had a 50% or greater reduction in pain days, compared with 68% of the patients treated with BTX-A. The mean reported reduction in pain intensity by visual analog scale over baseline was 56% for patients on the oral drug vs. 50% for patients who received the injections. Similar percentages of patients reduced their use of pain drugs in the amitriptyline (77%) and BTX-A groups (71%).
There were no significant between-group differences in either patient or physician assessment of improvement at 90 days, with 88% of patients on the oral medication and 84% of patients on the injections reporting improvement at study end. The investigators determined that 87% of patients improved while taking the antidepressant and 88% of patients improved after receiving the toxin.
Adverse events generally were higher in the amitriptyline group, including the side effects of weight gain (58% for the oral drug vs. 12% for BTX-A), somnolence (53% vs. 4%), dry mouth (44% vs. 14%), and constipation (39% vs. 0%).
The investigators acknowledged that BTX-A is both more expensive and more invasive than oral medications, and suggested additional research to determine which subgroups of migraine sufferers might benefit from the injections compared with other means of migraine prevention.
The study is part of the doctorate of Ms. Magalhães, who received a grant from the Brazilian Federal Agency for the Support and Evaluation of Graduate Education. A coauthor received a research grant from Brazil’s National Council for Scientific and Technological Development. The authors did not report conflicts of interest.