Comparison of subcutaneous dexmedetomidine versus clonidine as an adjuvant to spinal anesthesia: a randomized double blind control trial

Background: Alpha-2 adrenergic agonists like clonidine and dexmedetomidine prolong the duration of postoperative analgesia and improve the quality of subarachnoid block (SAB) when used as adjuvant in various routes. However, addition of these drugs by IV or intrathecal routes are known to cause hemodynamic instability. The subcutaneous (SC) route provides similar efficacy as IV administration with less hemodynamic instability and prolonged effect. Aims: To compare the efficacy of clonidine and dexmedetomidine as adjuvants to SAB when used subcutaneously. Materials and methods: A total of 90 patients were randomized into one of the three groups: Group P received 1 ml of Normal saline SC, Group D received 0.5 mcg/kg of dexmeditomedine SC and Group C received 1 mcg/kg of clonidine SC respectively after SAB with 3ml of 0.5% hyperbaric bupivacaine (15 mg). Time of onset of sensory and motor block, intraoperative hemodynamics, postoperative VAS scores, Richmond agitation sedation scale, duration of postoperative analgesia and mean paracetamol requirement in 24 hours were recorded. Results: Mean duration of postoperative analgesia was prolonged in group D (838.10±348.22 minutes) and group C (816.67±230.48 minutes) when compared to group P (332.10±110.91 minutes). Total paracetamol consumption was less in group D (1400.00±770.13 mg) and group C (1600.00±674.66 mg), whereas it was 1900.00±758.86 mg in group P. Hemodynamic parameters, maximum sensory level attained, and time to attain maximum sensory levels were comparable among the two groups. Conclusion: Both subcutaneous clonidine and dexmedetomidine prolonged the duration of postoperative analgesia and reduced analgesic requirements when used as adjuvants to SAB with stable hemodynamics, hence both of these drugs can be used effectively as adjuvants to SAB.