Extended Detection of Amphetamine and Methamphetamine in Oral Fluid.

Abstract

Amphetamine and methamphetamine are popular drugs of abuse worldwide and are important components of drug monitoring programs. Windows of detection for amphetamine and methamphetamine in oral fluid after high doses have not been investigated. Repeated high-dose ingestions are likely to cause positive samples for extended periods. Common routes of administration of amphetamine/methamphetamine in Norway are oral intake or injection. The aim of this study was to investigate windows of detection for amphetamine and methamphetamine in oral fluid from drug addicts under sustained abstinence during detoxification. Twenty-five patients admitted to a closed detoxification unit were included in this study. Oral fluid samples were collected daily in the morning and evening, and urine every morning for 10 days. A blood sample was drawn during the first 5 days after admission if the patient consented. Oral fluid results were compared with urine results to determine whether a new ingestion occurred. Oral fluid was collected with the Intercept oral fluid collection device. In-house cutoff concentrations for amphetamine and methamphetamine were 6.8 and 7.5 mcg/L, respectively, in oral fluid, and 135 and 149 mcg/L, respectively, in urine. Amphetamines were detected in 11 oral fluid, 5 urine, and 2 blood specimens from 25 patients. Patients self-reported amphetamines intake of up to 0.5-2 g daily. Windows of detection for amphetamine and methamphetamine in oral fluid were up to 8 days, longer than in urine at the applied cutoff values. These data confirm that oral fluid is a viable alternative to urine for monitoring amphetamine abuse, and that these substances might be detected in oral fluid for at least 1 week after ingestion of high doses. Such long detection times were, as far as we are aware, never reported previously for oral fluid amphetamines.