Considering unintentional exposure when testing for cocaine use via oral fluid testing

Area of Science:

• Forensic Toxicology
• Analytical Chemistry
• Pharmacology

Background:

• Oral fluid testing for cocaine use is common, but optimal cutoffs for intentional use versus unintentional exposure require clarification.
• Previous research has not fully addressed the correlation between cocaine and metabolite detection levels and self-reported use, especially when considering co-ingestion of other substances.

Purpose of the Study:

• To determine optimal cutoffs for cocaine detection in oral fluid that distinguish intentional use from unintentional exposure.
• To compare the accuracy of detecting cocaine and its metabolites against self-reported use, accounting for concurrent drug use.

Main Methods:

• Analysis of oral fluid samples from 1819 adult nightclub attendees using liquid chromatography quadrupole time-of-flight mass spectrometry.
• Comparison of detected cocaine and metabolite levels with self-reported cocaine and other drug use within the past 24 hours.

Main Results:

• 43.7% tested positive for cocaine exposure (≥1 ng/mL), while only 13.6% reported 24-hour use.
• An optimal cocaine concentration cutoff of ≥26 ng/mL best predicted self-reported use among those testing positive.
• Metabolite detection was the strongest predictor of self-reported use, outperforming cocaine detection alone, but higher cutoffs risked under-detection.

Conclusions:

• Detection of cocaine metabolites offers the most accurate classification of self-reported cocaine use in oral fluid.
• While higher cocaine concentration thresholds and metabolite detection improve specificity for intentional use, they may reduce sensitivity, potentially missing some instances of use.
• Further research is needed to balance sensitivity and specificity in oral fluid cocaine testing to accurately identify intentional use while minimizing false positives from unintentional exposure.