Benzoylecgonine (BE)
Definition
The major hydrolysis metabolite of cocaine, formed by carboxylesterase action on the methyl ester of cocaine. Half-life is around 6 hours in blood and longer in urine. BE is the standard urine marker for cocaine use because the parent cocaine clears within 4 to 6 hours but BE persists for two to three days.
- Formation
- Carboxylesterase hydrolysis of cocaine's methyl ester
- Blood half-life
- Around 6 hours
- Urine persistence
- 2 to 3 days
- Parent drug clearance
- 4 to 6 hours in blood
- Role
- Standard urine marker for cocaine use
Common questions
Why does BE's shorter blood half-life compared to its urine persistence matter for interpretation?+
A blood sample taken more than about a day after use may already show very low or undetectable BE, while urine can still test positive for days, so blood and urine results from the same subject can legitimately disagree depending on when each sample was collected relative to use.
Can BE detection alone establish impairment at the time of an incident?+
No. BE reflects that cocaine was used within roughly the preceding two to three days, not current impairment, so a positive BE result needs to be paired with parent cocaine levels, clinical signs, or other timeline evidence before impairment at a specific moment can be argued.
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