The Impact of Serum Drug Concentration on the Efficacy of Imipramine, Pregabalin, and their Combination in Painful Polyneuropathy

Objective: The aim of this study was to explore the serum concentration-effect relation for first-line drugs in neuropathic pain and to determine if efficacy could be increased.
Methods: Data from a randomized, placebo-controlled, cross-over trial on imipramine, pregabalin, and their combination in painful polyneuropathy were used. Treatment periods were of 4 weeks’ duration, outcome was the weekly median of daily pain rated by a 0 to 10 numeric scale, and drug concentrations were determined by high-performance liquid chromatography.
Results: In 47 patients, pain was reduced −1.0 (95% confidence interval [CI], −1.5 to −0.6) by imipramine, −0.4 (95% CI, −0.9 to 0.1) by pregabalin, and −1.6 (95% CI, −2.1 to −1.1) by combination therapy. On monotherapy, there was no difference between responders and nonresponders with respect to concentrations of imipramine (mean, 161 vs. 229 nmol/L, P=0.129) and pregabalin (mean, 9.8 vs. 11.7 μmol/L, P=0.178). There was no correlation between drug concentration and pain reduction for imipramine (r=0.17, P=0.247), whereas there was a marginally, positive correlation for pregabalin (r=0.28, P=0.057). There was no interaction between treatment and concentration classes (imipramine

Source: The Clinical Journal of Pain - November 8, 2017 Category: Anesthesiology Tags: Original Articles Source Type: research