A randomised controlled double blind study to assess the effect of oral tizanidine premedication on intraoperative isoflurane consumption in patients undergoing laparoscopic surgeries under general anaesthesia

Abstract

Tizanidine is an α 2 receptor agonist derived from clonidine with primary central myotonolytic action along with antinociceptive and anticonvulsant action. Unlike clonidine, there are few studies evaluating the role of tizanidine as an effective anaesthetic premedication. Hence this study was undertaken to evaluate oral tizanidine [2 mg and 4 mg] administered preoperatively in decreasing the intraoperative consumption of isoflurane. This prospective, randomised, double blind control trial was undertaken in 75 adult patients scheduled for elective laparoscopic surgeries. The subjects were randomly allocated into 3 groups with Group A (2 mg tizanidine), Group B (4 mg tizanidine), Group C (sugar pellet). The study drug was administered orally 90 minutes preoperatively. Intraoperative isoflurane consumption and end tidal isoflurane was recorded. Demographic data was comparable between the 3 groups. We observed a significant fall in isoflurane consumption in the tizanidine groups [Total: group A = 10.24 (2.07) ml, group B = 8.09 (2.17) ml, group C = 15.43 (4.77), p < 0.001; at 30 min: group A = 6.86 (0.91), group B = 5.22 (0.67), group C = 8.10 (1.15), p < 0.001; at 60 min: group A = 9.29 (0.73), group B = 7.92 (1.31), group C = 12.88 (2.45), p < 0.001; at 90 min: group A = 11.13 (0.83), group B = 10.25 (2.63), group C = 17.25 (2.5), p <0.001]. End tidal isoflurane was also significantly low in the tizanidine groups. Intergroup analysis showed no significant variation between tizanidine 2mg and 4mg. Oral tizanidine [2mg and 4 mg] is as effective and safe anaesthetic premedication in decreasing isoflurane consumption.