Dose related effects of oral clonidine pre-medication on bupivacaine spinal anaesthesia

Introduction: The duration of action of sub-arachnoid block is short, and one of the ways to overcome this is the use of oral clonidine.
Methods: 108 patients of ASA I and II, aged 18 to 65 years undergoing lower abdominal surgeries under spinal anaesthesia were randomized into three groups.. Control group A (n=36) no oral clonidine pre-medication, Group B (n=36) and group C (n=36) received 100 μg and 200 μg of oral clonidine pre-medication respectively, 1hr before spinal anaesthesia. Haemodynamic parameters were recorded. Sensory block, degree of motor blockage, and sedation were assessed.
Results: Clonidine prolonged the mean duration of motor block by 189.98±26.93 min (100μg) and 191.89±28.13 min (200μg) compared to 117.92±25.13 min in the control group p<0.05. The mean duration of analgesia was 188.19±35 min (100μg) and194±24.58 min (200μg) in the clonidine groups compared to 115.89±26.66 min in control group p<0.05. All the patients were awake in the control group while 71.43% and 100% were drowsy in groups B and C respectively.
Conclusion: Oral clonidine produces better clinical effects on the onset and duration of Bupivacaine spinal anaesthesia.

Keywords
Spinal anaesthesia; pre-medication; clonidine; duration of action; duration of action