Cannabinoids in multiple sclerosis. Opportunity or hazard?

Abstract

Based on patient reports, animal data, and in vitro experiments, evidence has emerged indicating a positive effect of cannabinoids as symptomatic treatment of spasticity and pain in multiple sclerosis. The recently published CAMS study was the first multicenter, randomized, placebo-controlled phase III trial to examine the efficacy of cannabinoids on symptoms related to MS. There was no treatment effect of cannabinoids on the primary outcome measure, a difference in the reduction of spasticity as assessed by the so-called Ashworth score. In contrast, significant effects on patient-reported spasticity and pain were documented. A major problem of the study was a high degree of patient unmasking in the active treatment group. In this review, the results of the CAMS study are discussed in the context of previous trials, the putative mechanism of action of cannabinoids and their adverse event profile.