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On the dermal absorption of cocaine
R C Baselt1, J Y Chang, D M Yoshikawa
1Chemical Toxicology Institute, Foster City, California 94404.
Journal of Analytical Toxicology
|November 1, 1990
Summary
Dermal cocaine exposure leads to detectable benzoylecgonine in urine. Even small doses absorbed through skin can impact drug test results, highlighting the need for careful interpretation.
Area of Science:
- Forensic Toxicology
- Pharmacokinetics
- Dermal Absorption Studies
Background:
- Cocaine is a widely abused stimulant drug.
- Urine drug testing is a common method for detecting cocaine use.
- The contribution of dermal absorption to overall cocaine exposure is not well-established.
Purpose of the Study:
- To investigate the extent of cocaine absorption through the skin.
- To quantify the urinary excretion of benzoylecgonine following dermal cocaine application.
- To assess the significance of dermal absorption in interpreting urine drug test results.
Main Methods:
- A controlled study involving the topical application of cocaine free base and cocaine hydrochloride to human volunteers.
- Collection and analysis of discrete urine specimens over a 96-hour period.
- Quantification of benzoylecgonine, a major metabolite of cocaine, in urine samples.
Main Results:
- Application of 5 mg cocaine free base resulted in a maximal urinary benzoylecgonine concentration of 55 ng/mL at 48 hours.
- A total of 58 micrograms (1.2% of the dose) of benzoylecgonine was excreted in urine within 96 hours.
- Application of 5 mg cocaine hydrochloride yielded a maximal urinary benzoylecgonine concentration of 15 ng/mL at 24 hours.
Conclusions:
- Dermal absorption of cocaine is a minor, yet significant, route of exposure.
- Urinary detection of benzoylecgonine following skin exposure can occur.
- These findings are crucial for accurate interpretation of low-level positive results in urine drug testing.