Antinociception without motor blockade after subarachnoid administration of S-(+)-ibuprofen in rats

This study was designed to determine whether the nonsteroidal anti-inflammatory drug (NSAID) sodium S-(+)-ibuprofen (IB), can be used intrathecally as a substitute analgesic for opiates to avoid the side effects of intrathecal narcotics. One week or more after surgical implantation of subarachnoid catheters, four groups of Sprague-Dawley rats were given 0.05 ml subarachnoid injections containing one of the following: Group A, normal saline (NS); Group B, IB 0.25 mg, 0.5 mg and 1.5 mg; Group C, morphine (M) 0.05 mg and 0.025 mg; Group D received NS or IB 1.5 mg. Animals were sacrificed for spinal cord examination one week after injection. Tail flick response latency (TFL) was determined before and 15, 30, 60, 120 and 180 minutes after each injection. TFL differences were compared. IB 1.5 mg vs NS, IB 0.5 mg vs NS, IB 0.25 mg vs M 0.05 mg, IB 0.25 mg vs M 0.025 mg, M 0.05 mg vs NS, and M 0.025 vs NS showed p < 0.05. IB 1.5 mg vs M 0.05 mg and M 0.025 mg, IB 0.5 mg vs M 0.05 mg and M 0.025 mg revealed no significant difference. No motor impairment was observed in any animal. Light microscopy of the spinal cord revealed no evidence of pathological changes in any animal (group D).