Marijuana DUI - California Background Information

Marijuana
Background

Marijuana comes from the hemp plant, Cannabis sativa. The principal psychoactive agent in marijuana is delta-9-tetrahydroc annabinol (9-THC or THC). 9-carboxy THC (also known as THC-COOH) is an inactive metabolite (bio-product) of 9-THC. While 9-THC is the pharmacologically active component of marijuana and is the source of the euphoric high, 9-carboxy THC is inactive and its presence has no effect on the user.

Marijuana produces a pleasant euphoria or “high” commonly followed by drowsiness. Intoxication temporarily impairs concentration, learning, and perceptual-motor skills. Thus, for at least 4-6 hours after a dose of marijuana, users probably function with reduced abilities. Preliminary studies suggest that performance is impaired long after the acute subjective effects have ended. Experienced pilots in a flight simulator were impaired for at least 24 hours after a dose; long after the subjective high had disappeared. Functional impairments are less understood in cases of prolonged, heavy marijuana use, because, although 9-THC accumulates in the body, behavioral and physiological tolerance also develops.

Metabolism and Excretion

Marijuana is usually smoked; transpulmonary absorption rapidly gets psychoactive drug to the brain. Since the drug is also absorbed from the gastrointestinal tract, although much more slowly, marijuana sometimes is eaten. 9-THC leaves the bloodstream and is distributed into different parts of the body where it is metabolized, excreted, or stored. The 9-THC that is stored in fatty tissue gradually reenters the blood stream at very low levels, permitting metabolism and eventual excretion. THC is metabolized extensively in the liver and the major metabolite is 11-nor-delta9- tetrahydrocannab inol-9-carboxyli c acid (9-carboxy THC).

Analysis and Detection Times

A two-step process is frequently used to test for marijuana. The first step is a qualitative screening procedure. This procedure typically uses an immunoassay (EIA, ELISA) method to detect the presence of marijuana metabolites. It provides only a positive or a negative result. Any positives identified using EIA or ELISA should be confirmed by an alternate method. There are multiple types of Gas or Liquid Chromatography/ Mass Spectrometry procedures (GC/MS or LC/MS) available to laboratories to confirm screening test results. These methods provide definitive molecular identification and quantitation of the drug .

With wide variations in metabolism, body fat composition, drug potency, and other factors, it is difficult to approximate how long 9-THC will be detected in the urine or blood of an individual. 9-THC could be present at detectable levels for 2 to 4 hours after use in the blood, and is rarely seen in the urine. However, 9-carboxy THC can be present at detectable for several days or even weeks. Studies have shown inexperienced smokers (one marijuana cigarette) may be positive for 1-3 days. But with repeated smoking, 9-THC accumulates in fatty tissue; so frequent, chronic smokers slowly release low levels of 9-THC over a longer time and may continue to test positive for the 9-carboxy THC metabolite for several weeks. A recent study1 monitored prison inmates with a history of chronic marijuana use. The last positive was found 17 days after last intake. Earlier literature suggests detection times of 30 days or longer for chronic cannabis users2. If one is not a first time user or a chronic user, detection times of a couple of days to a couple of weeks have been reported, but this can vary widely form one individual to another.

References

1. Smith-Kielland, et al., Urinary Excretion of 11-nor-9-Carboxy- delta9-THC and Cannabinoids in Frequent and Infrequent Drug Users. J.Anal.Toxicol. Vol.23 no. 5, pp.323-332, 1999.

2. Ellis GM JR, et al., Excretion patterns of cannabinoid metabolites after last use in a group of chronic users. Clin Pharmacol Ther 1985 Nov: 38(5):572-8.

3. Baselt, Randall C; Disposition of Toxic Drugs and Chemicals is Man, Seventh Addition, Biomedical Publications, Foster City CA, 2004.

4. Baselt, Randall C; Drug Effects on Psychomotor Performance, One Edition, Chemical Toxicology, November, 2000.