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A drug test (also often toxicology screen or tox screen) is a technical analysis of a biological specimen, for example urine, hair, blood, breath, sweat, or oral fluid/saliva—to determine the presence or absence of specified parent drugs or their metabolites.
Toxicology testing is commonly conducted during preclinical development for a substance intended for human exposure. Stages of in silico, in vitro and in vivo research are conducted to determine safe exposure doses in model organisms. If necessary, the next phase of research involves human toxicology testing during a first-in-man study.
Most cannabis drug tests yield a positive result when the concentration of THC-COOH in urine exceeds 50 ng/mL. [10] Urine testing is an immunoassay based test on the principle of competitive binding. Drugs which may be present in the urine specimen compete against their respective drug conjugate for binding sites on their specific antibody.
Most people who take a drug test take a presumptive test, cheaper and faster than other methods of testing. However, it is less accurate and can render false results. The FDA recommends for confirmatory testing to be conducted and the placing of a warning label on the presumptive drug test: "This assay provides only a preliminary result.
The fixed-dose procedure (FDP), proposed in 1992 by the British Toxicology Society, is a method to assess a substance's acute oral toxicity. [1] [2]In comparison to the older LD 50 test developed in 1927, this procedure produces similar results while using fewer animals and causing less pain and suffering. [3]
Chemical hair analysis may be considered for retrospective purposes when blood and urine are no longer expected to contain a particular contaminant, typically three months or less. Its most widely accepted use is in the fields of forensic toxicology , in pre-employment drug testing and, increasingly, in environmental toxicology .
An early life stage (ELS) test is a chronic toxicity test using sensitive early life stages like embryos or larvae to predict the effects of toxicants on organisms. [1] ELS tests were developed to be quicker and more cost-efficient than full life-cycle tests, taking on average 1–5 months to complete compared to 6–12 months for a life-cycle test.
Up-and-down procedure (or method) for toxicology tests in medicine is an alternative to the LD 50 test, in which animals are used for acute toxicity testing. [1] [2] It requires fewer animals to achieve similar accuracy as the LD 50 test because animals are dosed one at a time. [3]