Cyclobenzaprine for acute back pain.

Evidence • In 3 systematic reviews (9 to 46 RCTs, 820 to 5401 patients) of non-benzodiazepine muscle relaxants versus placebo, differences were statistically significant1-3: -Pain scores were about 12 points lower on a 100point visual analogue scale at 10 days.1 -There was undefined pain reduction (number needed to treat [NNT] of 4 to 7) at 2 to 7 days; an undefined target for global efficacy (NNT = 4) was achieved at 2 to 4 days.2 • Cyclobenzaprine versus placebo: -One systematic review (14 RCTs, 3023 patients) showed global improvement (NNT = 3) at about 10 days.4 -We pooled data from 2 publications with 2 RCTs each. —Pain relief (1389 patients) was achieved at 7 days in 50% of those taking 5 mg of cyclobenzaprine 3 times daily versus 38% taking placebo (NNT = 9; P < .001).5 No difference was noted in 5 mg versus 10 mg or 2.5 mg versus placebo. —No difference was noted between 30 mg extended release once daily and 10 mg immediate release 3 times daily (504 patients).6 • An RCT of cyclobenzaprine plus ibuprofen (867 patients) showed no benefit to adding ibuprofen.7 • An RCT of naproxen plus cyclobenzaprine (323 patients) showed no benefit to adding cyclobenzaprine at day 7, but only about 30% had frequent or continual back pain then.8