Sharma, S., Rajagopal, M.R., Palat, G., Singh, C., Haji, A.G., & Jain, D. (2009). A phase II pilot study to evaluate use of intravenous lidocaine for opioid-refractory pain in cancer patients. Journal of Pain and Symptom Management, 37, 85–93.

To determine the magnitude and duration of pain relief in patients receiving IV lidocaine and placebo infusions, to explore the efficacy and potential uses of IV lidocaine for pain relief in opioid-refractory cancer pain, and to evaluate the safety profile, specifically acute side effects

Patients received infusions of lidocaine and placebo in random order with 14 days between the two infusions. Patients were to record their average daily pain score for 14 days after each infusion.

• The study consisted of 50 patients.
• The mean age of patients was 67 years with a range of 34–91 years. 
• The sample consisted of 22 females and 28 males.
• All patients were at least 18 years of age suffering from opioid-refractory cancer pain. Patients had to consent to no change in analgesic therapy from 48 hours before and 24 hours after completion of the scheduled infusion.

This was a single-site study conducted in India.

This was a randomized, double-blind, placebo-controlled, crossover study.

Pain was measured using a numeric analog scale (NAS) ranging from 0–10, with 0 being no pain and 10 being worst imaginable pain.

• Onset of maximum analgesic effect after initiating lidocaine infusion was 40 minutes (SD = 16.28) compared to 74.8 minutes (SD = 33.39) for saline (placebo).
• Duration of pain relief after lidocaine was 9.3 days (SD = 2.5) compared to 3.8 days (SD = 1.8) with saline.
• The mean pain score during the 14-day observation period was 1.4 for lidocaine and 5.2 for placebo.
• Frequency of rescue medications after lidocaine infusion was 1.45 per day with lidocaine compared to 1.76 per day with placebo infusion.
• During the peri-infusion period, up to two hours post, a decrease in heart rate was observed.
• After lidocaine infusion, 26 patients experienced at least one side effect; 18 patients experienced at least one side effect after placebo.
• Side effects developed earlier in patients receiving the lidocaine infusions.
• Side effects included tinnitus, perioral numbness, sedation, lightheadedness, and headache. All were self-limited and did not require intervention. One patient withdrew from the study because of severe tinnitus.

The average duration of pain relief in this study after a single infusion of lidocaine was 9.34 days.

• The investigators did not account for the progressive nature of the disease and its possible effect on pain.
• The study used a lower dose of lidocaine at a slower rate of infusion compared to the available literature.
• A possible carryover effect (despite a 14-day interval between dosing) may have occurred.
• The study did not evaluate the safety profile of IV lidocaine.
• Findings did not differentiate between the effects of the intervention on nociceptive and neuropathic pain and analgesia.

Further studies are indicated to establish guidelines and investigate the safety profile for the use of IV lidocaine.