Comparison of pentazocine and pethidine for the treatment of shivering following subarachnoid block

Pethidine is one of the known drugs for treating post-spinal shivering; however, it is a controlled drug. Pentazocine, a specific kappa agonist, is widely available in West Africa and is not yet a controlled drug. A randomized, double-blind trial was performed to compare the efficacy of pentazocine and pethidine for the treatment of post-spinal shivering. One hundred ASA I and II patients undergoing surgeries below the umbilicus under spinal anesthesia were studied. Patients who developed shivering after the administration of intrathecal bupivacaine for spinal anesthesia were randomly allocated to 2 groups to receive either Intravenous (IV) pethidine 25mg (n=50) - group A, or IV pentazocine 30 mg (n=50) - group B. The time from the administration of the study drug to the reduction and complete disappearance of shivering, recurrence of shivering, and other adverse effects were determined. The two study groups did not differ significantly regarding patient characteristics. The difference between the mean time of administration of the study drug to the complete disappearance of shivering in group A (9.23±2.18 minutes) and B (6.70±1.15 minutes) was statistically significant (p<0.05). The onset of action was faster with pentazocine (94.04±16.20 seconds) compared with pethidine (151±34.01) (p<0.05). The pentazocine group had a higher recurrence of shivering than the pethidine group (30.8% vs 13.0%), though this difference was not statistically significant (p=0.14). Three patients (13.04%) had a recurrence of shivering in the pethidine group compared to 8 patients (30.77%) in the pentazocine group. There was no significant difference between the groups in terms of sedation, pulse rates, nausea, perioperative tympanic temperatures, and mean arterial pressures. No vomiting or respiratory depressions were observed. Pentazocine 30 mg and pethidine 25 mg were both equally effective in the treatment of shivering following subarachnoid block. Though pentazocine had a faster onset of action and abolished shivering earlier than pethidine, the rate of recurrence of shivering after treatment was however higher with pentazocine than with pethidine.