Objective.—To assess effectiveness and safety of tizanidine hydrochloride tablets for the prophylaxis of chronic daily headache.
Background.—Tizanidine hydrochloride is an α2-adrenergic agonist that inhibits the release and effectiveness of norepinephrine at both central sites (eg, the locus ceruleus) and the spinal cord. It acts as a central muscle relaxant and has antinociceptive effects. Preliminary research and retrospective analyses have suggested efficacy in treatment of both chronic tension-type headache and chronic daily headache with migrainous features.
Design.—Thirty-nine patients with more than 15 headache days per month (33 with migraine, 5 migrainous, 1 chronic tension-type) completed a 4-week baseline, with 31 completing a planned 12 weeks of treatment with tizanidine. Dosing was titrated from 2 mg at bedtime to a median daily dose of 14 mg (mean, 13.5; SD, 4.3; range, 4 to 20, divided over three doses per day) by treatment week 4.
Results.—The overall headache index through week 12 (headache frequency × average intensity × duration) declined significantly (P<.00000002), with a corresponding increase in mean percentage improvement from 49% for weeks 1 through 4, to 65% for weeks 5 through 8, and 64% for weeks 9 through 12 (P<.0182). During weeks 9 through 12, 67% had improved more than 50% compared to baseline. Overall headache frequency declined from 22.83 to 15.83 days per month (P<.00001), with frequency of severe headaches dropping from 7.52 to 3.58 days per month (P<.000035). Average headache intensity dropped from 1.83 to 1.07 (1-to-5 scale), peak intensity declined from 2.37 to 1.40, and mean duration was reduced from 6.96 to 4.00 hours per headache (P<.00001). Improvement also occurred on visual analog scales of overall headache status, mood, sleep, quality of life (P<.00001), and sexual function (P<.0075); as well as the Beck Depression Inventory-II (P<.00073).
Mild-to-moderate adverse events reported by more than 10% of the patients included somnolence, asthenia, and dry mouth. Only 3 patients discontinued treatment due to adverse events: somnolence and dry mouth alone (n = 1), or in combination with either hyperkinesis (n = 1) or constipation (n = 1). One patient had elevated liver enzymes that returned to normal after the drug was discontinued.
Conclusions.—The results provide preliminary support for the efficacy, safety, and tolerability of tizanidine in the prophylaxis of chronic daily headache.