A comparative study of pre-operative oral clonidine and pregabalin on post-operative analgesia after spinal anesthesia

OBJECTIVES: Pregabalin and clonidine have anti-nociceptive properties. This study assesses their efficacy in prolonging the analgesic effect of spinal anesthesia and post-operative analgesic requirement in patients undergoing vaginal hysterectomy. MATERIALS AND METHODS: A total of 90 females in the age group of 30-60 years were randomly allocated in to three groups of 30 each, to receive either oral clonidine (150 μg) or oral pregabalin (150 mg) or oral multivitamin as placebo 1.5 h before spinal anesthesia with 3ml (15 mg) of 0.5% hyperbaric bupivacaine. Intensity of pain was measured on a visual analog scale (VAS) at the end of operation (0 h) then at 1,2,4,6,12 and 24 h thereafter. Diclofenac sodium intramuscularly 1 mg/kg was provided when the VASscore was >4 in the study period. Sedation was defined by Ramsay sedation scale at 0,6,12 and 24 h. Side-effects such as nausea and vomiting, respiratory depression and dryness of mouth were noted. RESULTS: The VAS scores were significantly less in the pregabalin group compared with the clonidine group at 6,12 and 24 h post-operatively with a P < 0.0001. More sedation was seen in the clonidine group than in the pregabalin group (P < 0.05). Analgesic consumption and VAS scores were lower in clonidine and pregabalin group compared with the placebo group (P < 0.05). CONCLUSION: Oral pregabalin (150 mg) prolongs the post-operative pain relief after spinal anesthesia but produces less sedation compared with oral clonidine (150 μg).