Clonidine, an alpha-2-adrenergic agonist, have a clinically relevant analgesic action but also a hypotensive action, when administered spinally. In this study, therefore, the analgesic, hemodynamic effects of intrathecal clonidine were studied in patients undergoing lower abdominal and lower limb surgery under spinal anaesthesia. Sixty patients of ASA I-II were randomly divided to two groups. One group received clonidine 15 μg mixed with 15.5 mg 0.5% bupivacaine and the other group an identical saline volume mixed with bupivacaine as above, in a double-blind fashion. Onset and duration of sensory and motor block, blood pressure, heart rate and sedation were followed during and after the operation. The duration of sensory analgesia (regression of the block to L2) was longer in the clonidine group (mean 178 min) than in the control group. Duration of motor blockade was also longer in the clonidine group compared to the control group. Mean arterial pressure and heart rate were significantly lower in the clonidine group compared to the control group. Postoperative the clonidine patients needed less doses of diclofenac sodium than those in the control group. More patients in the clonidine group were sedated 3–4 hr than control group (p < 0.05). Addition of clonidine prolonged the bupivacaine spinal block.

Keywords: Clonidin; Bupivacaine spinal block alpha-2-adrenergic agonist.