Comparative clinical study of effect of neostigmine and ketamine for postoperative analgesia.

The purpose of the study was to evaluate and compare the role of neostigmine and ketamine as an additive to epidural bupivacaine to prolong the duration of postoperative analgesia. A double-blind randomised study was done on 60 adult patients, of both sexes, between 18 and 50 years, belonging to ASA grades I and II, undergoing below umbilical surgeries under epidural anaesthesia. All the patients were divided into three groups of 20 each to receive 20 ml of 0.5% bupivacaine with either 1 ml of normal saline, 100 mg of neostigmine or 50 mg of ketamine (both diluted with 1 ml normal saline). The mean (+/- SD) time to the first rescue analgesic administration was significantly prolonged by neostigmine [543.30 (+/- 133.40) minutes] and ketamine [292.00 (+/- 71.93) minutes] compared to the control group with saline [212.80 (+/- 62.49) minutes]. Postoperative 24-hour pain score was also less in neostigmine group. When compared to ketamine group neostigmine showed superior postoperative pain relief. Both neostigmine and ketamine demonstrated better haemodynamic stability with less incidence of hypotension. There was no increased incidence of nausea and vomiting or any other side-effects. In conclusion, it can be said neostigmine is a good adjuvant to epidural block to produce adequate pain relief without increased incidence of adverse effects.