Effect of repeated cocaine administration on detection times in oral fluid and urine.

Detection times reported for single-dose studies may not predict detection times following repeated cocaine dosing. Although repeated cocaine administration can result in drug accumulation and extended excretion time, there is a paucity of data from controlled dosing studies with repeated drug administration. We compared detection times for cocaine and benzoylecgonine (BZE) in oral fluid and BZE in urine following single and repeated cocaine dosing. Two groups of cocaine-experienced subjects participated in these studies. The single-dose group received cocaine by intravenous, intranasal, and smoked administration. The repeated dose group received daily escalating oral cocaine doses culminating in a total of 1,250-2,000 mg. Oral fluid and urine specimens following the last dosing were analyzed by gas chromatography-mass spectrometry. Detection times were determined as the time to the last positive specimen. The effect of repeated dosing was to extend oral fluid detection times for cocaine approximately fourfold and BZE detection times sevenfold, whereas urine BZE detection times were extended twofold. Because cocaine abusers frequently self-administer higher and repeated doses, we conclude that the short detection times observed in single-dose studies underestimate the utility of oral fluid for detection of cocaine abuse in realistic settings.