BACKGROUND: The discovery of opioid receptors and ligand in the brain and spinal cord lead to the feasibility of their intrathecal use. Pethidine is the only narcotic that has been shown to be effective intrathecally for surgery. This is because it as a phenyl-piperidine derivative and has a structure and action similar to that of local anesthetic. METHODS: It is a prospective study of 50 patients belonging to ASA grade I and II physical status were administered intrathecal Pethidine (preservative free) 1mg/kg body weight for lower limb surgeries. The time of onset and level of sensory blockade, onset and degree of motor blockade, hemodynamic parameters, time for regression of sensory and motor blockade, duration of postoperative analgesia and side effects were assessed in the patients. RESULTS: Majority of the procedures performed were below knee amputation or external fixation. The mean duration of onset of sensory block was 6.55 mins (SD:±0.79) and onset of motor block was 8.39mins (SD:±0.83). Peak level of sensory block was attained at L1 level in majority of patients (82%). Degree of motor block was II degree in 66% of patients. Mean time required for motor recovery was 62.2 mins (SD: ±5.0). This was followed by sensory regression at 94.6mins (SD:±7.3). Mean duration of postoperative analgesia was 333 minutes (SD:±29.9). Side effects observed were hypotension, nausea, vomiting, sedation, and pruritus. CONCLUSION: Pethidine (preservative free) 1mg/kg body weight can be used intrathecally as a sole anesthetic agent to provide prolonged postoperative analgesia associated with hemodynamic stability and early ambulation in patients undergoing lower limb surgeries.

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