A randomized, double-masked, placebo-controlled pilot trial of extended IV lidocaine infusion for relief of ongoing neuropathic pain.
OBJECTIVE
To determine the dose-response effect and safety of IV lidocaine at different dose infusion rates on spontaneous ongoing neuropathic pain.


METHODS
In this double-masked, placebo-controlled, parallel study conducted in an outpatient clinical research center, patients with peripheral neuropathic pain received a 6-hour infusion of three doses (1, 3, and 5 mg/kg) of lidocaine or placebo. The main outcome measure was relief of pain intensity (percentage pain intensity difference [PID %]). Other measures were responder rate, adverse events, and correlation between lidocaine levels and PID %.


RESULTS
There was a significant difference in the median PID % between the group treated with lidocaine 5 mg/kg/h (-34.60) and the placebo group (-11.96, P=0.012). Such effect began 4 hours after the onset of treatment and lasted until the end of the study. Lidocaine at lower infusion rates was no better than placebo in relieving pain. A modest but significant correlation was found between methylethylglycinexylidide (MEGX) levels and pain relief (R=0.60). There were no serious adverse events, but in two patients lidocaine was stopped prematurely.


CONCLUSIONS
Lidocaine at 5 mg/kg/h was more effective than placebo at relieving neuropathic pain. The effect started 4 hours after the onset of treatment and continued for at least 4 hours after the end of the infusion. Additional research is needed using higher infusion rates with larger sample sizes to confirm these results and to explore the role of MEGX in the relief of neuropathic pain.
Tremont-Lukats
Ivo W
IW
Department of Neurology, University of Wisconsin-Madison, Madison, WI 53792, USA.
Hutson
Paul R
PR
Backonja
Misha-Miroslav
MM
D000328:Adult; D000779:Anesthetics, Local / Q000008:administration & dosage* / Q000009:adverse effects; D002908:Chronic Disease; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D008012:Lidocaine / Q000008:administration & dosage* / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D009437:Neuralgia / Q000175:diagnosis / Q000188:drug therapy*; D010147:Pain Measurement; D010865:Pilot Projects; D015990:Placebo Effect; D016896:Treatment Outcome
D000779:Anesthetics, Local; D008012:Lidocaine