The effectiveness of cyclobenzaprine hydrochloride, a new tricyclic skeletal muscle relaxant, was shown in patients with long-term intractable pain of cervical and lumbar origin aggravated by skeletal muscle spasm and tenderness. The investigation was double-blind and randomized, comparing cyclobenzaprine hydrochloride (10 mg three times a day) with diazepam (5 mg three times a day) and with placebo. After two weeks of treatment, the 16 patients in the cyclobenzaprine group showed an overall improvement in pain variables as did the 16 patients in the diazepam group. No serious adverse reactions to cyclobenzaprine were observed in the study. However, dry mouth due to cyclobenzaprine's anticholinergic action and mild degrees of drowsiness were encountered more often than with diazepam or placebo.
(JAMA 240:1151-1152, 1978)
Brown BR, Womble J. Cyclobenzaprine in Intractable Pain Syndromes With Muscle Spasm. JAMA. 1978;240(11):1151–1152. doi:10.1001/jama.1978.03290110049018