Effects of oral melatonin premedication on hemodynamic responses to intubation, anesthetic requirements and postoperative sedation: A randomized trial.

Abstract

Sedative effects of melatonin may have an additive effect on general anesthesia (GA). We compared hemodynamic response to intubation following oral premedication with melatonin versus placebo. Induction dose of propofol, isoflurane and fentanyl consumption were also compared. This prospective, double-blinded study was conducted in fifty patients randomized into two equal groups. Group M received oral melatonin 6 mg and group P a placebo two hours before surgery. All patients were induced with intravenous propofol of 1.5-2.5mg/kg till loss of response to verbal commands, three minutes after vecuronium, laryngoscopy was done and trachea was intubated. Heart rate (HR) and mean arterial pressures (MAP) were recorded before premedication, before induction, immediately after induction and then at 1,3,5 and 10 minutes after intubation. Mean HR was comparable in both groups throughout the study period. Group M had significantly lower MAP before induction and immediately after induction (P < 0.05). At all other time points MAP remained comparable in both groups. Mean isoflurane consumption was significantly lower in group M compared to group P (14.8 ± 4.2 vs 19.7 ± 3.2 mL). Propofol requirement for induction was also significantly lower in group M (102.4 ± 19.6 vs 122.4 ± 26.3mg). Intraoperative fentanyl consumption was comparable. Oral premedication with melatonin 6mg administered two hours before surgery significantly reduced MAP before and after induction of GA with a significant reduction in dose of propofol requirement. Titrating induction dose of propofol till loss of response to verbal commands did not effectively attenuate responses to laryngoscopy and intubation following melatonin oral premedication.