Comparison of ketamine versus lignocaine intravenous infusion in refractory cancer pain: a prospective randomised double-blind controlled study

Objective To compare the analgesic efficacy, adverse effect profile, incidence of acute pain crises and opioid-sparing effects of intravenous ketamine versus lignocaine infusions in patients with refractory cancer pain. Methods A prospective, randomised, double-blind, controlled trial was conducted at Basavatarakam Indo American Cancer Hospital and Research Institute (October 2023–January 2025). 66 adults with refractory cancer pain, defined as pain inadequately controlled despite an oral morphine equivalent (OME) dose exceeding 200 mg/day, were randomised equally to receive either intravenous ketamine (0.3 mg/kg/hour) or intravenous lignocaine (2 mg/kg/hour), each administered as two 6-hour infusions separated by 12 hours. The primary outcome was effective pain relief, defined as a ≥50% reduction in pain severity. Secondary outcomes included adverse effects, acute pain crises during 6-week follow-up and postinfusion changes in OME dose. Results Effective pain relief was achieved in 84.8% of the ketamine group and 72.7% of the lignocaine group (p=0.228). Both groups demonstrated significant reductions in OME dose from baseline (p<0.01 for both), with no significant between-group difference (p=0.738). Adverse effects were significantly more frequent with ketamine than lignocaine (30.3% vs 9.1%; p=0.03). Acute pain crises during follow-up were numerically more common in the ketamine group (42.9% vs 29.2%), though this difference was not statistically significant (p=0.307). Conclusions Ketamine and lignocaine demonstrated comparable analgesic efficacy and opioid-sparing effects in refractory cancer pain. Lignocaine, however, offers a more favourable safety profile with significantly fewer adverse effects, supporting its consideration as a preferred option in this clinical setting.