Efficacy of Paracetamol Plus Lignocaine versus Lignocaine Alone for Pain on Propofol Injection: A Randomised Controlled Trial

Introduction: Propofol triggers endothelial irritation and nociceptor activation, producing early injection pain. Lignocaine blunts this response but does not abolish it completely. A brief systemic analgesic may help close this residual gap. This randomised evaluation tested whether intravenous paracetamol added to lignocaine further reduces the frequency and intensity of pain during induction. Aim: To assess the efficacy of paracetamol plus lignocaine versus lignocaine alone for propofol injection pain. Materials and Methods: This double-blinded, randomised, parallel-group trial was conducted at a tertiary care centre in the Department of Anaesthesiology, Krishna Institute of Medical Sciences (Deemed to be University), Karad, Maharashtra, India, from May 2023 to August 2024 (16 months) {n=98; American Society of Anaesthesiologists (ASA) I-II adults, 20–60 years; Body Mass Index (BMI) 19-30 kg/m²}. Group 1 received intravenous paracetamol 15 mg/kg infused over 10 minutes before theatre, plus lignocaine 2% (2 mL, diluted to 5 mL) with 2-minute venous occlusion. Group 2 received the identical lignocaine protocol without paracetamol (1:1, n=49 each). After tourniquet release, 25% of the propofol induction dose (2.5 mg/kg total) was injected over five seconds through the same cannula and pain was scored immediately on a 0-3 Verbal Rating Scale (VRS). Primary comparisons used risk ratio with 95% confidence intervals and Chi-square (χ²); ordinal severity was analysed using a trend/non parametric test. Two-sided α=0.05; intention-to-treat analysis was applied. Results: Baseline characteristics were similar between groups: age 38.2±10.1 vs 37.6±9.8 years; sex 28/21 vs 26/23 (M/F); BMI 24.9±2.8 vs 25.1±2.7 kg/m²; ASA I/II 30/19 vs 32/17 (Group 1 vs Group 2). Pain occurred in 12/49 patients receiving paracetamol+lignocaine versus 28/49 receiving lignocaine alone {Relative Risk (RR) 0.43, 95% Confidence Interval (CI) 0.25-0.74; Absolute Risk Reduction (ARR) 32.7%; Number Needed to Treat (NNT=4); p=0.001). Severity distribution: none 37 vs 21; mild 10 vs 14; moderate 2 vs 10; severe 0 vs 4 (p=0.0013). No patient in either group developed injection-site complications (erythema, phlebitis, or swelling). Both regimens were well-tolerated. Conclusion: Intravenous paracetamol, when added to standard lignocaine pretreatment, substantially decreases both the likelihood and intensity of propofol injection pain without causing new local adverse effects. This approach is simple, inexpensive and immediately transferable to routine practice.