P-glycoprotein inhibitors improve effective dose and time of pregabalin to inhibit intermittent cold stress-induced central pain.

Pregabalin (PGB) is a valuable therapeutic drug against chronic pain. Here we attempted to perform the combinatorial drug therapy with P-glycoprotein (P-gp) inhibitors to lower therapeutic dosage of PGB in the intermittent cold stress-induced fibromyalgia-like pain model. Single intracerebroventricular (i.c.v.) PGB injection exerted long-lasting anti-hyperalgesic effects for 72 h, while the effect of PGB given intraperitoneally (i.p.) disappeared within 3 h. Importantly, the pretreatment with P-gp inhibitors markedly prolonged the PGB (i.p.) effects, which lasted for 72 h. These results suggest that the combinatorial treatment with P-gp inhibitor enables the prolongation of dose-interval for PGB.