Pharmacological research : the official journal of the Italian Pharmacological Society
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Activation of cannabinoid CB1 receptors suppresses pathological pain but also produces unwanted side effects, including tolerance and physical dependence. Inhibition of fatty-acid amide hydrolase (FAAH), the major enzyme catalyzing the degradation of anandamide (AEA), an endocannabinoid, and other fatty-acid amides, suppresses pain without unwanted side effects typical of direct CB1 agonists. However, FAAH inhibitors have failed to show efficacy in several clinical trials suggesting that the right partnership of FAAH inhibition and pathology has yet to be identified. ⋯ Both FAAH inhibitors synergized with paclitaxel to reduce 4T1 and HeyA8 tumor cell line viability without reducing viability of non-tumor HEK293 cells. Neither FAAH inhibitor reduced viability of non-tumor HEK293 cells in either the presence or absence of paclitaxel, suggesting that nonspecific cytotoxic effects were not produced by the same treatments. Our results suggest that FAAH inhibitors reduce paclitaxel-induced allodynia without the occurrence of CB1-dependence in vivo and may, in fact, enhance the anti-tumor actions of paclitaxel in vitro.