A randomized, prospective, double-blind, comparative trial was carried out to explore the efficacy and tolerability of nimesulide (a cyclooxygenase-2 [COX-2] selective inhibitor) compared to ibuprofen in relieving acute lumbosacral back pain.

The study recruited 104 patients (aged 18-65 years) having acute low back pain. Participants were randomly assigned to either oral nimesulide (100 mg twice daily for ten days) group or oral ibuprofen (600 mg three times daily for ten days).

Back stiffness, mean of the visual analog scale (VAS) pain intensity and the pain relief, physical assessment results, and functional status were the outcome parameters. At each visit, all the adverse effects were precisely recorded. 

Both nimesulide and ibuprofen remarkably improved all the outcomes of pain and back function estimated from the third day of treatment. In both groups, an improvement was noted in the participant's capacity for daily tasks. After ten days, a substantial difference was witnessed between the two therapies in favor of the nimesulide group.

Compared to ibuprofen, nimesulide was found to be more effective in improving lateral bending measurements. In the modified Schober test, pain intensity score, and back stiffness scores, both nimesulide and ibuprofen therapies offered comparable degrees of improvement.

Compared to nimesulide, more gastrointestinal side effects were noted with ibuprofen, and the comparison displayed an important trend. In the nimesulide group, ten adverse effects occurred in 7 (13%) patients, and in the ibuprofen group, 13 adverse effects occurred in 11 (21%) patients.

For the general practice management of acute low back pain, nimesulide is an effective and well-tolerated therapeutic agent.