Effect of intravenous lidocaine associated with amitriptyline on pain relief and plasma serotonin, norepinephrine, and dopamine concentrations in fibromyalgia.

Author(s): Vlainich R, Issy AM, Sakata RK

Affiliation(s): Department of Anesthesiology, Universidade Federal de Sao Paulo, Rua Tres de Maio 61, Sao Paulo, SP, Brazil.

Publication date & source: 2011-05, Clin J Pain., 27(4):285-8.

Publication type: Randomized Controlled Trial

OBJECTIVE: The objective of this study was to evaluate the effect of intravenous lidocaine combined with amitriptyline on pain relief and plasma serotonin, norepinephrine, and dopamine levels. METHODS: A prospective, randomized, double-blind comparative study was conducted in 30 patients. All patients received 25 mg amitriptyline; monotherapy group (n=15) received 125 mL saline, and combined therapy group (n=15) received 240 mg lidocaine in 125 mL saline once a week for 4 weeks. Serotonin, norepinephrine, and dopamine were measured in plasma at time zero (T0) and after 4 weeks (T4). Pain intensity was rated on a numerical scale at the beginning of the study and weekly for 4 weeks. RESULTS: All patients were females and the mean age was 44.7+/-10.5 years for monotherapy group and 40.9+/-11.6 years for combined therapy group. No difference in pain intensity at baseline was observed between groups, with a decrease after treatment in monotherapy group (T0: 7.0+/-1.2 and T4: 4.0+/-2.1) and in combined therapy group (T0: 7.6+/-0.8 and T4: 4.1+/-2.3). Plasma serotonin and norepinephrine levels were similar in the 2 groups at T0 and T4. An increase in dopamine levels was observed in monotherapy group from the beginning to the end of treatment. CONCLUSIONS: Combined administration of 240 mg intravenous lidocaine (once a week) and 25 mg amitriptyline for 4 weeks did not modify pain intensity or plasma serotonin, norepinephrine, or dopamine concentrations in fibromyalgia patients.