An open label dose finding trial of tizanidine [Zanaflex™] for treatment of fibromyalgia

Objectives: To determine whether tizanidine [Zanaflex(TM)] would demonstrate clinical efficacy in patients with fibromyalgia [FMS] in an open label study over 14 weeks. Methods: Forty-six consecutive patients with a diagnosis of FMS were treated with tizanidine. Prior to and at seven and 14 weeks each patient was evaluated by the total number of tender points [TePs], the Fibromyalgia Impact Questionnaire [FIQ] score, and visual analog scales [VAS] for pain, sleep, fatigue, and patient global assessment. Patients were also analyzed based on employment status with an employed/retired [E/R] group and a disabled/applying [D/A] group. Results: Of the 46 initial patients, 30 patients completed seven weeks and showed a significant decrease in TePs [P < 0.001] and a significant improvement in VAS pain [P < 0.01], VAS sleep [P < 0.05], VAS fatigue [P < 0.02], and FIQ scores [P < 0.01]. By week 14, improvement was limited to TePs [P < 0.01] and VAS fatigue [P < 0.01]. The severity of FMS at the beginning of the study was not significantly different between the E/R group and the D/A group. There was significant improvement in the E/R group in TePs, VAS pain, fatigue, and FIQ scores at both weeks seven and 14. In contrast, this was not seen in the D/A group. Conclusion: Tizanidine is a useful medication in the treatment of FMS as judged by this open label uncontrolled study. The response as judged by TePs, VAS pain and fatigue, and FIQ scores was significantly better in the E/R group as opposed to the D/A group although there was no significant demographic difference between the groups. Employment status appears to be an important variable in the response achieved in this clinical trial.