van de Donk T, et al. - Researchers undertook this experimental randomized placebo-controlled 4-way crossover trial including 20 chronic pain patients with fibromyalgia to determine the analgesic efficacy of inhaled pharmaceutical-grade cannabis. Four different cannabis varieties with exact knowledge on their [INCREMENT]9-tetrahydrocannabinol (THC) and cannabidiol (CBD) content: Bedrocan (22.4-mg THC, <1-mg CBD; Bedrocan International BV, Veendam, the Netherlands), Bediol (13.4-mg THC, 17.8-mg CBD; Bedrocan International BV, Veendam, the Netherlands), Bedrolite (18.4-mg CBD, <1-mg THC; Bedrocan International BV, Veendam, the Netherlands), and a placebo variety without any THC or CBD were tested. Spontaneous or electrical pain responses were not affected with any of the treatments greater than placebo, although a 30% decrease in pain scores was observed in more subjects receiving Bediol compared to placebo, with spontaneous pain scores correlating with the magnitude of drug high. They observed a significant increase in pressure pain threshold with cannabis varieties containing THC relative to placebo. THC plasma concentrations increased but with a decrease in THC-induced analgesic effects when cannabidiol inhalation was enhanced. This suggests that THC and CBD have synergistic pharmacokinetic but antagonistic pharmacodynamic interactions. This experimental trial shows that in chronic pain patients, inhaled cannabinoids display complex behavior with just small analgesic responses after a single inhalation.