Does intravenous lidocaine reduce fibromyalgia pain?: A randomized, double-blind, placebo controlled cross-over study

Objective. To determine if intravenous lidocaine has an analgesic effect in fibromyalgia pain. Method. A randomized, double-blind, placebo controlled cross-over study of 75 consenting adult patients with pain due to fibromyalgia. Patients received either 48 ml placebo (0.9% saline) intravenously over 24 h or Lidocaine 960 mg (48 mi 2% lidocaine) over a similar period. After 4 weeks the patients returned, those who initially received placebo were given lidocaine, those who initially received lidocaine given placebo, again intravenously over 24 h. Average pain was measured using a 0-10 cm visual analogue scale and recorded on a daily basis for the 4 week study period. Analgesic consumption as number of tablets taken was also recorded daily. Results. 63 patients provided results (44 female, 19 male) with an average age of 45 years and duration of fibromyalgia pain of 93 months. The: average pre-treatment pain VAS score was 7.31 and did not change after placebo. After lidocaine infusion there was a significant Fail to 6.5 (95% C.L. 5.81-7.19) during the first week, 6.6 (95% C.L. 5.85-7.33) after the second week, 6.6 (95% C.L. 5.88-7.36) after the third and 6.98 (95% C.L. 6.27-7.69) after the fourth week (p < 0.01). There was no change in analgesic consumption after either infusion. Side-effects were seen in 11 patients after lidocaine infusion and in 6 after placebo infusion. Eight patients got more than 50% reduction in pain scores with lidocaine while only one got similar relief after placebo infusion. Conclusion. Intravenous lidocaine produces analgesia in some patients with fibromyalgia, and the duration of this relief outlives both the infusion time and plasma half-life of the drug.