Detection of Drugs in Simultaneously Collected Samples of Oral Fluid and Blood.

Simultaneously collected samples of oral fluid and blood in a naturalistic setting could provide a qualitative impression of the relative detection times of drugs in oral fluid compared to blood. The aim of this study was to compare detections of different drugs in oral fluid and blood from a large material of paired samples. The study included results from 930 paired oral fluid and blood samples collected from drivers suspected for driving under the influence of drugs. Oral fluid was collected using the Intercept device. Blood samples were screened using an ultra high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS-MS) method and positive results were confirmed and quantified with a different analytical method. Oral fluid samples were analyzed using UHPLC-MS-MS. The drugs included in the study were: amphetamine, methamphetamine, tetrahydrocannabinol (THC), diazepam, N-desmethyldiazepam, clonazepam, alprazolam, nitrazepam, oxazepam, morphine, 6-monoacetylmorphine (6-MAM), methadone and buprenorphine. The drugs detected more frequently in oral fluid compared to blood were amphetamine (497 positive in oral fluid/408 positive in blood), methamphetamine (332/232), oxazepam (106/36), morphine (65/31) and 6-MAM (19/0). The drugs detected less frequently in oral fluid compared to blood were THC (224 positive in oral fluid/407 positive in blood), diazepam (137/160), N-desmethyldiazepam (183/188), clonazepam (148/307), alprazolam (47/68), nitrazepam (16/29) and buprenorphine (31/59). For methadone, the number of detections was the same in oral fluid and in blood (23/23). The results indicate that for amphetamine, methamphetamine, morphine and 6-MAM, relative detection time is longer in oral fluid than in blood, while for benzodiazepines, the results indicate that relative detection time is shorter in oral fluid than in blood. For oxazepam and buprenorphine, the results were dependent on the cut-off limits used. Regarding THC, the detection time in oral fluid depends on the sampling method. The relative detection time was shorter than in blood when using the Intercept device.