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.