Drugs of abuse screen

Keywords: Toxicological screening, Drugs toxicological screen, Cannabinoids, Amphetamine screen urine, Amphetamine

Specimen:

20 mL urine (random specimen).

If required for forensic or other official purposes, adequate standards of identification and secure sample custody must be maintained and documented.

Method:

Chromatography, mass spectrophotometry, immunoassay, 'spot' tests.

Official drug screening may require definitive identification of a drug, usually by GCMS.

Application:

Detection of drug overdose.

Identification of unauthorised taking of legal or illegal drugs by patients with suspicious clinical features.

Screening for drug-taking in eg, employees, sports competitors, drivers of vehicles involved in accidents.

Monitoring of patient compliance with drug-free or methadone programme.

See also Forensic toxicology and Laxatives.

Interpretation:

If the drug taken is known (eg, paracetamol, salicylate, theophylline), measurement of plasma levels may be more appropriate.

The presence of drug and/or metabolites indicates past or present drug taking.

Urinary levels of drugs or metabolites vary with the drug involved, the time since the last dose, the dose taken and individual pharmacodynamics.

Assay sensitivity depends on the analytical method, and some drugs are not excreted in urine or detected by certain assays. Consult pathologist.

Reference:

Warner EA et al. Am J Med 2003; 115(1): 54-58.