Patients (112) with acute low-back pain of recent onset were recruited to this double-blind, randomized, placebo-controlled parallel group study in general practice to evaluate the efficacy and tolerability of the muscle relaxant, tizanidine. They were treated for 7 days with tizanidine (4 mg three times daily) or matching placebo. Aspirin tablets (300 mg) were taken as required as ‘rescue’ medication. Symptoms were assessed by the patient and doctor before treatment, and after 3 and 7 days. Patients recorded pain and aspirin consumption in a daily diary. Both treatments were effective. In patients who had taken no medication prior to entry, aspirin consumption was almost halved in the first 3 days of taking tizanidine compared with placebo ( P = 0.037). Results for pain at rest, pain at night, restriction of movement and pain on movement suggest that tizanidine may give greater improvement, earlier. No serious drug-related adverse events or abnormal biochemistry or haematology were observed in either group. Drowsiness occurred in 22% of patients taking tizanidine although, in patients with severe acute low-back pain, sedation, analgesia and bed rest might be beneficial and desired. Considerably more patients given aspirin/placebo had gastro-intestinal side-effects ( P = 0.018). In conclusion, tizanidine may reduce the need for analgesics and be useful in the treatment of acute low-back pain.
