SASOM: CLINICAL MEETING

ACTION OF DAGGA AND MANDRAX AND THEIR BIOPERSISTENCE

DAGGA (, , POT, WEED, )

Marijuana is a mixture of dried leaves and flowering tops of the plant . ∆-9- (∆-9-THC) is the chief active ingredient, which sometimes constitutes more than 7% of marijuana material (61 different have been identified). Cannabis or the cannabinoids are collective terms for psychoactive compounds derived from C sativa. Hashish is the dried resin collected from the flower tops.

Dagga is usually smoked (in South Africa often mixed with Mandrax). Absorption from the oral route is poor ( 5 – 20%).

∆-9-THC is difficult to detect in plasma (mass spectrometry with high-pressure gas or liquid chromatography ---- GC-MS).

∆-9-THC may accumulate in fatty tissue faster than it can be eliminated. This leads to longer detection times in urine for chronic users than for occasional users.

Both immunoassays and GC-MS chromatographic procedures can detect ∆-9-THC and its metabolites in the urine. Urine concentrations do not correlate with symptoms or degree of exposure. A positive result indicates only the likelihood of prior use.

Immunoassays are used for routine screening of cannibinoids in the urine. These provide only a preliminary analytical test results and must be considered screening procedures only. All specimens identified as positive on the initial immunoassay test must be confirmed by using gas chromatography-mass spectrometry methods.

Duration of detection: Following a single dagga cigarette, ∆-9-THC metabolites are detectable for several days. In casual users cannabinoids may be detected for up to 2 weeks, and up to 4 weeks in heavy users. Depending upon the assay, chronic cannabis users who have stopped using marijuana can continue to have positive urine results:

• An average of 16 days (up to 46 days) before the first negative and up to 77 days (average 27 days) before it was less than the cut off of 10 ng/ml for 10 consecutive days.

• A study of 13 chronic marijuana users demonstrated positive EMIT urine assays for 3 to 25 days after cessation of smoking. The excretion half-life for the delta-THC-7-oic acid metabolite ranged from 0,8 to 9,8 days.

Laboratory interference: Urine cannibinoid analyses are especially vulnerable to adulterants. Addition of salt, sodium hypochlorite (Jik), vinegar, benzalkonium chloride (as in some eyedrop preparations), soap (especially dishwashing detergents) to the urine, may all produce false negatives. Ingestion of high doses of ascorbic acid (3 g) and cranberry juice (750 ml) may reduce or lower the concentration of ∆-THC metabolites.

Cross reactivity: Drugs/agents which may cause false positive results include hempseed oil, ibuprofen and naproxen.