Comparative Efficacy of Intrathecal Buprenorphine Versus Clonidine as Adjuvants To 0.75% Isobaric Ropivacaine in Subarachnoid Block: A Prospective Randomized Double-Blind Study

Abstract

Background:

Intrathecal adjuvants are frequently combined with local anesthetics to enhance the quality and duration of spinal anesthesia. Ropivacaine, a long-acting amide local anesthetic with reduced cardiotoxicity compared to bupivacaine, provides effective sensory blockade with relative motor sparing. The addition of adjuvants such as buprenorphine, a partial μ-opioid receptor agonist, or clonidine, an α₂-adrenergic agonist, may further improve analgesic efficacy and perioperative hemodynamic stability. However, comparative evidence regarding their relative effectiveness when combined with intrathecal 0.75% isobaric ropivacaine remains limited.

Aim:

To compare the efficacy and safety of intrathecal isobaric ropivacaine (0.75%) combined with buprenorphine versus clonidine in patients undergoing lower limb orthopaedic and lower abdominal surgeries under subarachnoid block.

Methods:

This prospective, randomized, double-blind study included 66 patients (ASA I–III), aged 18–60 years, scheduled for elective or emergency lower limb orthopaedic and lower abdominal surgeries. Patients were randomly allocated into two groups (n=33 each). Group A received 3.5 mL of 0.75% isobaric ropivacaine with clonidine 30 μg, while Group B received 3.5 mL of 0.75% isobaric ropivacaine with buprenorphine 60 μg intrathecally. Primary outcomes included onset and duration of sensory and motor blockade, and duration of analgesia. Secondary outcomes included hemodynamic parameters, postoperative pain scores (VAS), and incidence of adverse effects. Statistical analysis was performed using appropriate parametric and non-parametric tests, with p < 0.05 considered significant.

Results:

Both groups achieved effective sensory and motor blockade suitable for surgery. The onset of sensory blockade at T10 was statistically significant between groups (p = 0.005). Hemodynamic parameters demonstrated significant intergroup differences at selected time intervals, particularly in heart rate and blood pressure measurements. The duration of postoperative analgesia was prolonged in the buprenorphine group, whereas clonidine demonstrated comparatively greater hemodynamic modulation. The incidence of adverse effects was minimal and comparable between groups.

Conclusion:

Intrathecal ropivacaine (0.75%) combined with buprenorphine provides prolonged postoperative analgesia, while clonidine offers enhanced hemodynamic modulation. Both adjuvants are effective and safe; however, buprenorphine may be preferred when extended postoperative analgesia is prioritized. Further large-scale studies are warranted to confirm these findings.