Medical science monitor : international medical journal of experimental and clinical research
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Randomized Controlled Trial
Effect of Baricity of Bupivacaine on Median Effective Doses for Motor Block.
BACKGROUND The median effective dose (ED50) of a drug gives the amount or dose of drug needed to produce effective therapeutic response or desired effect in at least 50% of the population taking it. Our study focused on determining the ED50 required for effective motor block using hyperbaric and plain bupivacaine, and evaluated the influence of baricity on the ED50 required for motor block. MATERIAL AND METHODS A total of 38 patients were randomly assigned into 2 groups according to the baricity of bupivacaine: group P received plain bupivacaine and group H received hyperbaric bupivacaine. ⋯ RESULTS The ED50 required for effective motor block in spinal anesthesia was 7.20 and 10.05 mg in groups H and P, respectively. Their relative motor blocking potency ratio was found to be 0.72. CONCLUSIONS The ED50 for motor block was significantly decreased using hyperbaric bupivacaine intrathecally compared with plain bupivacaine, and the baricity of bupivacaine obviously affected the ED50 for the motor block.