There are cases where marijuana metabolites have been detected for as long as sixty days after last use, since small amounts from fat go back into blood and appear in the urine. Depending on the amount of drug stored in the fat tissues, detection may be possible in the urine for many days after last use. Blood levels of δ 9-THC peak and start to decline in half the time it takes to smoke a marijuana "joint." Concentrations are known to fall by almost 90 per cent in the first hour. For example, δ 9-Tetrahydrocannabinol (THC), the active ingredient in marijuana, is highly fat-soluble, resulting in rapid reductions in blood levels as the drug is being distributed to the various tissues. Some drugs are fat-soluble and are deposited in fat tissues. The amount of drug stored depends on the nature of the drug, the quantity, duration of ingestion, the tissue holding the drug and the frequency of use. Once the absorbed drug enters the blood stream it is rapidly distributed to the various tissues in the body. the speed at which the drug reaches the brain and other body organs) whereas intravenous and inhalation routes result in the fastest absorption. Drugs taken orally are usually the slowest to be absorbed (i.e. There are various routes of drug administration oral (e.g., drinking Alcohol or swallowing pills), intravenous (e.g., Heroin injected into a vein) and inhalation (e.g., smoking Marijuana snorting Co-Caine sniffing Glue). DRUG PROPERTIES: ABSORPTION, DISTRIBUTION, AND ELIMINATION PHASESĭetection of a drug depends largely on its absorption, distribution, and elimination properties. These problems will be discussed and the various laboratory procedures that are used to combat these problems will be examined. The most frequent problems that confront the toxicology laboratory relate to developing technology that can determine how much and when the drug was taken, how long after use the tests are capable of showing positive results, the causes and rates of false positive and false negatives, and how tests can be "beaten" by employees. Although recent literature indicates that significant refinements and modifications to drug testing technology have been made, the complexity of drug effects is so great that many problems exist in interpretation of the test results. DRUG TESTING METHODS AND CLINICAL INTERPRETATIONS OF TEST RESULTSĪs interest increases in employment-related drug testing, the technologies and the interpretive skills of analysts continue to evolve.
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