Subcutaneous Lidocaine for Cancer-Related Pain

Background: Intravenous lidocaine infusions have been shown to be effective for cancer related pain, but access is restricted to acute care settings. If able to be shown to be safe and effective, the subcutaneous route could expand access to residential hospices or patients' homes. Objectives: This randomized, double-blind, placebo controlled, 2 × 2 crossover trial evaluated the effectiveness, safety, toxicity, and impact on quality of life of a limited duration subcutaneous lidocaine infusion (SCLI) for chronic cancer pain. Methods: Patients with the life expectancy of three months or more, who were experiencing cancer-related pain with a worst severity of at least 4 on a 0-10 scale despite a trial of at least one opioid and appropriate adjuvant analgesic, received two subcutaneous infusions at least a week apart; lidocaine 10 mg/kg over 5.5 hours and saline placebo. The primary outcome was either a reduction in worst pain intensity of two points out of 10 or a reduction in 24 hours opioid dose of at least 30% without worsening of pain scores, in seven days. Results: The SCLI was only effective for two subjects. One of these subjects experienced a drop in worst pain score and the other experienced a reduction in opioid dose. Conclusions: A weight-based subcutaneous infusion of lidocaine does not achieve sufficiently predictable blood levels for determining lidocaine responsiveness. This study does not allow any conclusion to be drawn on whether or not lidocaine would have been more effective had it been titrated to higher blood levels.