Background: Effective postoperative analgesia is essential for early mobilization and improved recovery following surgeries under subarachnoid block. The limited duration of action of hyperbaric bupivacaine necessitates the use of adjuvants. Clonidine, an α2-adrenergic agonist, has been shown to prolong spinal anesthesia and enhance analgesia in a dose-dependent manner. Aim: To compare the efficacy and safety of two different doses of intrathecal clonidine (15 µg and 30 µg) as an adjuvant to 0.5% hyperbaric bupivacaine in patients undergoing below-umbilical surgeries. Methods: This prospective, randomized, double-blinded comparative study was conducted from March 2024 to March 2025 at Sree Mookambika Institute of Medical Sciences, Kulasekharam, Tamil Nadu, India. Adult patients (ASA I–II) undergoing elective surgeries under spinal anesthesia were randomly allocated into two groups. Group A received 18 mg of 0.5% hyperbaric bupivacaine with 15 µg clonidine, while Group B received 18 mg of 0.5% hyperbaric bupivacaine with 30 µg clonidine. Parameters assessed included onset and duration of sensory and motor block, duration of postoperative analgesia, hemodynamic variables, and adverse effects. Data were analyzed using SPSS software; continuous variables were compared using paired t-test and categorical variables using Chi-square test, with p < 0.05 considered statistically significant. Results: The onset of sensory and motor block was comparable between the two groups. However, Group B (30 µg clonidine) showed a statistically significant prolongation in the duration of sensory block, motor block, and postoperative analgesia compared to Group A (15 µg clonidine) (p < 0.05). Hemodynamic changes such as hypotension and bradycardia were more frequent in Group B but remained clinically manageable. Conclusion: Intrathecal clonidine in a dose of 30 µg, when used as an adjuvant to 0.5% hyperbaric bupivacaine, provides superior prolongation of postoperative analgesia and block duration without significant adverse effects. It can be considered an effective and safe option for enhancing spinal anesthesia in below-umbilical surgeries.

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