Single-dose kinetics of deuterium-labelled cannabinol in man after intravenous administration and smoking

The single dose pharmacokinetics of deuterium-labelled cannabinol (2H2-CBN) were evaluated in six male cannabis users with different degree of abuse after smoking an average dose of 19 mg and after intravenous administration of 20 mg CBN. Plasma levels were measured for up to 72 h with selected ion monitoring by GC/MS using 2H7-CBN as internal standard. The systemic availability of smoked CBN was found to be 39 +/- 26% (min-max 6-65%). The mean plasma clearance was 19.1 +/- 2.6 ml min-1 kg-1 and the volume of distribution was determined to 50 +/- 23 l kg-1. The apparent terminal half lives for CBN were 32 +/- 17 h and 43 +/- 29 h after intravenous administration and smoking, respectively.