od of marijuana use is by smoking it. This method produces a rapidonset of drug activity but only fifty to seventy-five percent of the THC present in marijuana isabsorbed in the body. THC, or tetrahydrocannabinol, is the active intoxicating chemical inmarijuana. Differences in individual smoking habits also result in considerable differences in theamount of cannabinoids (a term describing the active chemicals in marijuana) absorbed into thebody. The smallest amount of THC present in a joint, a slang term for a marijuana cigarette, thatwill produce desirable effects in man is around five milligrams. When smoked the onset of drugaction is about five to fifteen minutes; peak effect occurs around sixty minutes; the duration ofaction is often four hours or longer. Interestingly, while the peak psychological effect or “high”occurs around sixty minutes after smoking, the peak increase in pulse rate associated with thedrug occurs at fifteen minutes and then rapidly declines. Studies of drug distribution have shownthat tissues highly concentrated with blood, such as the liver, lung, kidney, and spleen attainrelatively high levels of drug concentration. One very interesting exception is the brain. Althoughit too receives a high blood flow, brain cannabinoid levels remain far below blood levels.It has been established that the liver processes the THC into further metabolites. Most ofthe cannabinoids that are excreted from the body are in the form of these metabolites rather thanthe parent compound. Studies of the elimination of THC and its metabolites from the body inman and in animals indicate that excretion occurs very slowly. The main route of elimination ifthrough the bile and feces. Unlike alcohol, relatively little of the drug passes through the kidney.About fifty percent of the THC taken into the body is eliminated in the first twenty-four hours. Inman, traces of the drug can still be found as long as eight days after usage. In ...
