Subcutaneous Lidocaine Infusion for Pain in Patients with Cancer.

BACKGROUND: Intravenous lidocaine is effective in treating pain. Limited studies have assessed the effectiveness and safety of subcutaneous lidocaine infusions.

METHODS: We conducted a retrospective review of patients with cancer who received subcutaneous lidocaine infusions for pain. Patient characteristics, pain scores and opioid doses before and after lidocaine, and details of infusions were recorded. We identified three time periods of interest. T0 is defined as the 24-hour period immediately before commencing lidocaine treatment. T1 is defined as the 24-hour period before lidocaine was ceased. T2 is defined as the first 24-hour period after lidocaine was ceased. In addition, the overall impression of the effectiveness of lidocaine was subjectively evaluated by the authors.

RESULTS: Twenty patients (13M;7F) received lidocaine. Two patients received it twice, totaling 22 episodes. The median lidocaine dose was 0.67 mg/kg/h with the median duration being 5.5 days. The median worst pain score at T0 and T1 was 8.5 and 5.5, respectively. The difference in the mean pain scores was 3.2 95% CI (2.1, 4.4; p < 0.001). In 15/22 episodes (68%), patients experienced a decrease in pain scores of more than 2. The median morphine oral equivalent (MOE) daily doses at T0, T1, and T2 were 425, 362.5, and 275 mg, respectively. The difference in the mean MOE between T0 and T1 was -126 (95% CI [-281, 28]; p = 0.13). The difference in the mean MOE between T0 and T2 was -207 (95% CI [-370, -44]; p = 0.025). Lidocaine was subjectively deemed effective in 10/22 episodes (45%). There were no documented adverse events attributed to lidocaine. Univariate analyses did not identify any subgroups likely to benefit from lidocaine.

CONCLUSION: Subcutaneous lidocaine infusions may be used safely in cancer pain management and is effective in some patients.