Purpose. The effects of oral administration of clonidine on sympathetic and endocrinological responses were investigated in patients undergoing elective laparoscopic cholecystectomy.

Methods. Twenty adult patients were allocated randomly to the clonidine group (n = 10) or the control group (n = 10). The control and clonidine groups received placebo on clonidine 4μg·kg⁻¹ orally 2 h before the induction of anesthesia. All patients underwent laparoscopic cholecystectomy under isoflurane anesthesia. The hemodynamic variables were observed perioperatively. Plasma concentrations of cortisol, ACTH, noradrenaline, adrenaline, and dopamine were determined before administration of clonidine or placebo, 2 h after the beginning of the operation, and 3 h after the end of the operation.

Results. Systolic and diastolic blood pressures were lower in the clonidine group than in the control group immediately after endotracheal intubation and extubation (P < 0.05). Patients in the clonidine group showed lower plasma concentrations of noradrenaline 2 h after the beginning of the operation than patients in the control group (P < 0.01). However, the plasma concentrations of the other hormones did not differ between groups.

Conclusion. Clonidine premedication prevents sympathetic hyperactivity but does not suppress hypothalamo-pituitary-adrenocortical responses in patients undergoing laparoscopic cholecystectomy.