Fig. 10. Percentage self-reported pain relief between placebo, morphine, and mexiletine. The use of morphine was associated (general estimating equation model) with significantly higher self-reported percentage pain relief error bars compared with mexiletine ( P < 0.0001) and placebo ( P < 0.0001). Reprinted with permission from Wu CL et al. , Anesthesiology 2008; 109:289–96.