The effects of nabilone on insomnia in fibromyalgia: Results of a randomized controlled trial

Purpose: Fibromyalgia (FM) is a chronic pain syndrome with generalized tender points. Insomnia affects over 75% of patients with FM, and tricyclic antidepressants are the mainstay of treatment. Cannabis has been used by patients with FM to help sleep. We evaluated nabilone, a synthetic cannabinoid, for insomnia in FM. Method: We conducted a randomized double-blind active control equivalency crossover trial to compare nabilone (0.5-1.0mg qHS) to amitriptyline (10-20mg qHS) in FM patients with chronic insomnia. Subjects received each drug for two weeks with a two-week washout. The primary outcome was sleep quality using the Insomnia Severity Index (ISI) and the Leeds Sleep Evaluation Questionnaire (LSEQ); secondary outcomes included pain, mood, quality of life and adverse events (AEs). Results: Thirty-one subjects were enrolled and 29 completed the trial (26 female, mean age 49.5y). While sleep was improved by both nabilone and amitriptyline, nabilone was superior to amitriptyline (ISI difference=3.2, 95%CI 1.2-5.3). Nabilone was marginally better on the restfulness LSEQ sleep quality scale (difference=0.5 (0.0-1.0) but not on wakefulness (difference=0.3 (-0.2, 0.8)). Adverse events were all mild-moderate and were more frequent with nabilone (102) than amitriptyline (53). Most common AEs for nabilone were dizziness (10), nausea (9) and dry mouth (7). Conclusion: Nabilone is effective in improving sleep in patients with FM and is well tolerated. Low dose nabilone given once daily at night may be considered as an alternative to amitriptyline. Longer trials are needed to determine the duration of effect and to characterize long-term safety.