Many drugs of abuse are excreted in the urine. The duration of time that drugs can be detected in the urine is affected by multiple factors.
|
Factor |
Effect on Drug Detectability |
|---|---|
|
rate of drug metabolism |
slow increases length of time; fast decreases length of time |
|
renal function and diuresis |
low increases length of time; high decreases length of time |
|
bladder emptying |
urinary retention increases |
|
drug accumulation |
may be longer in habitual users |
|
sensitivity of analytic system |
ultrasensitive increases the length of time; insensitive decreases |
As a general rule of thumb, most drugs will be undetectable 6 half-lives after the last drug ingestion.
| Drug | Usage Pattern | Typical Duration of Detectability |
|---|---|---|
|
amphetamines |
|
2 days |
|
barbiturates, short-acting |
|
1 day |
|
barbiturates, intermediate acting |
|
2-3 days |
|
barbiturates, long-acting |
|
>= 7 days |
|
benzodiazepines |
|
3 days |
|
cannabinoids (THC) |
single use |
3 days |
|
|
moderate use (3-4 days per week) |
5 days |
|
|
heavy use (daily) |
10 days |
|
|
chronic heavy smoker |
21-27 days |
|
cocaine (metabolites) |
|
2-3 days |
|
codeine |
|
2 days |
|
methadone (metabolites) |
|
3 days |
|
methamphetamines |
|
2 days |
|
methaqualone |
|
>= 7 days |
|
morphine |
|
2 days |
|
norpropoxyphene |
|
1-2 days |
|
phencyclidine |
|
8 days |
where:
• The duration of detectability is affected by the cutoff used to call positive.
• The value for detectability of 2 days for opiates (codeine, morphine) is based on the previous detection limits of 300 ng/mL (raised in 1998 to 2,000 ng/mL)
Purpose: To determine the length of time a drug of abuse can be detected in the urine.
Specialty: Toxicology, Emergency Medicine, Critical Care
Objective: laboratory tests
ICD-10: Z86.4,
