Comparative efficacy of clonidine versus magnesium sulfate as an adjunct to lignocaine in intravenous regional anesthesia for postoperative analgesia: A prospective, randomized, double-blind study.

Background and Aims: Intravenous regional anesthesia (IVRA) is a very good technique to be used in unstable patients. Various adjuvants have been added, but till date, there is no ideal adjuvant. Clonidine is one of the most widely used adjuvants in IVRA. However, it has many side effects. Hence, the search continues for a better adjuvant. The aim of the present study was to compare the efficacy of clonidine versus MgSO4 as an adjunct to lignocaine in IVRA for postoperative analgesia and to compare their side effect profile.

Material and Methods: This prospective double-blind randomized controlled study was conducted in a tertiary care institute. Forty adult patients were included. Patients were assigned into two groups; Group 1 ( n = 20) received 3 mg/kg of 2% lignocaine + 50% MgSO4 1.5 g diluted with normal saline to 40 ml. Group 2 ( n = 20) received 3 mg/kg of 2% lignocaine + clonidine 150 μg diluted with normal saline to 40 ml. Pain score, time to first rescue analgesic (TTFA), total number of rescue analgesics required, and the side effects of the two drugs were compared for 24 h postoperatively.

Results: The mean TTFA was significantly longer in Group 1 (193.9 ± 38.4 min) than in Group 2 (169.5 ± 33.3 min); P < 0.05. The mean number of rescue analgesics required was 1.6 ± 0.7 in Group 1 as compared to 2.1 ± 0.8 in Group 2 ( P < 0.05). More serious side effects such as hypotension and bradycardia were noted with clonidine, although all patients experienced transient pain during intravenous injection of MgSO4 .

Conclusion: MgSO4 provides better postoperative analgesia as compared to clonidine when used as an adjunct to lignocaine in IVRA with fewer side effects.