An open-label dose-titration study of the efficacy and tolerability of tizanidine hydrochloride tablets in the prophylaxis of chronic daily headache

Objective.-To assess effectiveness and safety of tizanidine hydrochloride tablets for the prophylaxis of chronic daily headache. Background.-Tizanidine hydrochloride is an alpha (2)-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 X average intensity X 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.