|MadSci Network: Medicine|
I looked this up in a Substance Abuse textbook and also asked one of our substance abuse experts in our department. It seems there are no substances that you can take to avoid detection of a drug. However, what can be done is basically to drink lots of water to try to dilute out the substance of abuse such that it is no longer detectable. The most common test in emergency rooms for example, is the use of the traditional TLC (thin layer chromatography) "toxicology screen" to detect what are presumably high doses of drugs. A TLC tox screen is NOT sufficiently sensitive for diagnosis of low-dose use of illicit drugs. When TLC is used, false negatives are common. TLC sensitivity is in the range of 2 micrograms per mL. Thus if you dilute out the drug by drinking lots of water or using diuretics you may avoid detection. In forensic settings TLC is not admissible and one must use more sensitive methods such as Gas chromatography or Mass Spec. On a final note, there are substances which one can ingest which can come out as illicit in a tox screen. For example, ingestion of a large quantity of poppy seeds (as in poppy seed muffins) will register as an opiate positive tox screen (since poppy seeds have morphine). References Substance Abuse: A comprehensive textbook second edition Williams and Wilkins hope this helps, cheers, gabriel vargas, md/phd
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