Oral clonidine premedication decreases energy expenditure in human volunteers

Abstract

Purpose: Clonidine not only stops postoperative shivering and decreases oxygen consumption, but also decreases energy expenditure with or without a reduction in shivering during recovery from anaesthesia. It is important to see if clonidine decreases energy expenditure at rest since this may contribute to a postoperative decrease in energy expenditure. The authors tested the hypothesis that oral clonidine decreases energy expenditure at rest. Methods: Twenty healthy male volunteers were randomly assigned to one of two groups. Ten volunteers received oral clonidine approximately 5 μg- kg-1 (clonidine group), while the remaining 10 volunteers received placebo (control group). Blood pressure, heart rate, body temperature at the tympanic membrane, sedation score graded from 1 (alert) to 5 (sleeping and difficult to be aroused by tactile stimulation) were measured before and at 30-min intervals for three hours after administration of clonidine or placebo. Measurements of enengy expenditure and respiratory quotient were made with a head canopy system at one-minute intervals and averaged over 15 min before, and at 30, 60, 90, 120, and 180 min after administration of clonidine or placebo Results: Sedation score increased from 1 to 3 (median) after clonidine administration. Energy expenditure decreased from 1452 ± 225 kcal · 24hr-1 (mean ± SD) at baseline to 1258 ± 175 kcal · 24hr-1 at 180 min after clonidine administration (P <0.05). Conclusion: This study suggests that oral clonidine at a dose of 5 μg · kg-1 decreases energy expenditure at rest.