Effect of oral low dose clonidine premedication on postoperative pain in patients undergoing abdominal hysterectomy: a randomized placebo controlled clinical trial.

UNLABELLED This study evaluated the effect of oral low dose clonidine premedication on postoperative pain and hemodynamic status of the patients during abdominal hysterectomy under general anesthesia. METHODS This study is a randomized, placebo controlled double-blinded clinical trial. After approval of the study protocol by the Ethics Committee 60 patients were recruited and written informed consents were obtained. Two hours before surgery, patients in the treatment group (n=30) received a single oral dose of 100 microgram of clonidine and those in the placebo group received an oral dose of placebo (n=30). The severity of postoperative pain was assessed at 2nd, 6th, 12th and 24th hours after the operation using the visual analog scoring system (VAS score). Also the total dose of administered analgesics during 24 hours after the surgery and the interval between the surgery and the first request of analgesic were compared between the two groups. Systolic blood pressure and pulse rate were recorded during the surgery and at the post anesthesia care unit. Drug related adverse effects were also evaluated. RESULTS Postoperative pain VAS during 24 hours after the surgery was significantly (P=0.001) lower in clonidine group (3.86 +/- 0.89) compared to the placebo group (4.86 +/- 0.93). Also, the interval between surgery and the first request of analgesic in clonidine group was 4.13 +/- 3.27 hours on of longer duration (P=0.02) compared to 2.88 +/- 3.74 hours in placebo group. The mean heart rate and systolic blood pressure were lower in the clonidine group. CONCLUSION A single oral 100 microg dose of clonidine administered 2 hours before abdominal hysterectomy significantly reduces the severity of postoperative pain.