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The variety of different body matrices that can be analysed to determine the presence or absence of different psychoactive substances is extensive, ranging from semen to cerumen (earwax). There are, however, practical limitations to the extent to which biological samples can be used, and the mechanism of collection and supervision of samples are critical to the procedure. This contribution focuses on those biological samples that are commonly used for testing within various drug treatment settings, namely urine, saliva, blood and hair. Urinalysis is routinely used in hospital-based services, blood in forensic environments, hair analysis for medico-legal cases, and saliva (oral fluid) tests in the prison service and outreach units.
Rationale
Many would advocate that the assessment of psychoactive drug use could reliably be achieved using self-report from the drug user (client). However, there are issues around the method of enquiry the context, purpose, interviewer characteristics, etc.1 that may bias self-report. Circumstances in which the user sees the self-report to the enquirer about drug use as influential on his or her own continued treatment or possible loss of privileges are particular examples.
Selecting the biological matrix
The drug being tested for and the period of time that the clinician wishes to consider influence the choice of body fluid. Blood gives the most accurate measurement of drugs currently active in the system, whereas urine provides a somewhat longer timeframe (Table 1), but with less quantitative accuracy. Hair provides a substantially longer timeframe.
Table 1.
Approximate duration of detectability in urine of commonly used substances and some of their metabolites Substance Duration of detectability
Amphetamine 23 days
Benzodiazepines:
short-acting (triazolam) 1 day
intermediate (temazepam) 24 days
long-acting (diazepam/nitrazepam) 7 days or more
Cannabinoids (marijuana):
single use 12 days
moderate use (daily use) 10 days
chronic heavy use 36 days
Cocaine 68 hours
metabolite/benzoylecgonine 23 days
LSD 1 day
Nicotine 12 hours
metabolite/cotinine 23 days
Opiates:
6-monoacetylmorphine 24 hours
morphine/codeine 1 day
dihydrocodeine 1 day
morphine glucuronides 2 days
codeine glucuronides 3 days
Opioids:
methadone (maintenance dosing) 79 days
buprenorphine 23 days
buprenorphine metabolites 7 days
propoxyphene 0.52 days
The detection rates in time may be useful for people taking drugs teasts
Hippy