Pharmacokinetic properties of the synthetic cannabinoid JWH-018 and of its metabolites in serum after inhalation.

Each year, synthetic cannabinoids are occurring in high numbers in the illicit drug market, but data on their pharmacology and toxicology are scarcely available. Therefore, a pilot study was performed to assess adverse effects of JWH-018, which is one of the oldest and best known synthetic cannabinoids. Six subjects inhaled smoke from 2 and 3mg JWH-018. The drug and nine of its metabolites were analyzed in their blood samples taken during the following 12h by liquid chromatography-mass spectrometry (LC-MSMS). The maximum concentration of JWH-018 reached 2.9-9.9ng/ml after inhalation and markedly decreased during the next 1.5h, followed by a multiexponential decline (t1/2 in median 1.3h and 5.7h). The concentration of the pentanoic acid metabolite was slightly higher than that of the 3-, 4- and 5-hydroxypentyl metabolites and of the 6-hydroxyindol metabolite. The data also suggest a multiexponential decline and slow terminal elimination of JWH-018 and all metabolites. The detection of JWH-018 and of its metabolites in serum requires high analytical sensitivity. The pharmacokinetic properties of inhaled JWH-018 are similar to that of THC. A slow terminal elimination of drug and metabolites may lead to accumulation in chronic users.