An in vitro experiment on the interaction of charcoal or wheat bran with 11-nor-9-carboxy-Δ(9)-tetrahydrocannabinol and its glucuronide.
The rather long yet variable terminal half-lives and detection times since last use of urinary cannabinoids may partly be attributed to their enterohepatic circulation which generally can be interrupted or restricted by chemical adsorbents. Therefore, an in vitro experiment was performed to study the adsorptionbinding of 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH) and its glucuronide to activated charcoal and wheat bran remaining concentrations were determined by liquid chromatographytandem mass spectrometry. Adsorptionbinding of 1,000 ngmL of free or conjugated THC-COOH was complete using as little as 5 mg of charcoal whereas adsorptionbinding to wheat bran increased with increasing amounts. Taking of remedies affecting enterohepatic recycling of THC-COOH and its glucuronide may challenge interpretation of cannabinoid concentrations used to detect or assess frequency of drug use or the time since last drug consumption.