1. ¹Department of Internal Medicine VI, Clinical Pharmacology and Pharmacoepidemiology, University of Heidelberg, Heidelberg, Germany
2. ²Institute of Legal Medicine, University of Heidelberg, Heidelberg, Germany
3. ³University Hospital Pharmacy, Heidelberg, Germany

Correspondence: G Mikus, (gerd.mikus@med.uni-heidelberg.de)

Received 29 December 2006; Accepted 21 February 2007; Published online 4 April 2007.

Abstract

After cannabis consumption there is only limited knowledge about the pharmacokinetic (PK) and metabolic properties of 11-nor-9-carboxy-⁹-tetrahydrocannabinol (CTHC), which is formed by oxidative breakdown from ⁹-tetrahydrocannabinol (THC). Despite widely-varying concentrations observed in smoking studies, attempts have been made to interpret consumption behavior with special regard to a cumulated or decreasing concentration of CTHC in serum. Ten healthy nonsmoking white male individuals received 5 mg CTHC intravenously over 10 min. Highest serum concentrations of CTHC were observed at the end of the infusion (336.861.7 g/l) followed by a quick decline. CTHC concentration could be quantified up to 96 h after administration, with a terminal elimination half-life of 17.65.5 h. Total clearance was low (91.224.0 ml/min), with renal clearance having only a minor contribution (0.1360.094 ml/min). This first metabolite-based kinetic approach will allow an advanced understanding of CTHC PKs data obtained in previous studies with THC.