Detection of synthetic cannabinoids in oral fluid using ELISA and LC-MS-MS.

Synthetic cannabinoids are often referred to as 'Spice' or K2 compounds. Detection of these compounds in oral fluid has, to date, been limited to chromatographic procedures such as liquid chromatography with tandem mass spectrometry detection. We report the first analytical immunoassay for the screening of some synthetic cannabinoids in oral fluid specimens collected with the Quantisal™ device. JWH-200 was chosen as the calibration standard, because parent compounds, not metabolites, are predominantly detected in oral fluid. The immunoassay is capable of detecting JWH-200, JWH-018, JWH-073, JWH-022, AM-2201, AM-2232 and AM-1220. The assay was validated according to accepted laboratory protocols and applied to 32 authentic oral fluid specimens previously analyzed using LC-MS-MS at an accredited laboratory. The assay is sensitive, with a cutoff concentration of 0.25 ng/mL, and has a wide working range from 0.1 to 5 ng/mL. Intra- and interday precision were determined to be <10%. The screening method was completely validated and characterized; critical aspects of the screening included the incorporation of a preincubation step that improves the sensitivity of the assay to allow relevant concentrations of synthetic compounds in oral fluid to be detected.

Immunoassay screening of diphenhydramine (Benadryl®) in urine and blood using a newly developed assay.

Diphenhydramine (DPH) is a common over the counter antihistamine that produces drowsiness and has the potential to cause driving under the influence of drugs-related accidents. To date there are no commercially available immunoassay screening kits for its detection in biological fluids such as urine and/or blood. We describe a newly developed enzyme-linked immunosorbent assay (ELISA) screen and report on its utility in the analysis of authentic specimens taken from volunteers. The assay is specific for detection of DPH and does not detect closely related antihistamines like brompheniramine, chlorpheniramine, and doxylamine. There is a varying amount of cross-reactivity seen with certain tricyclic compounds, due to similarities in side chain structure with DPH. Intra- and interday precision of the assay were determined to be less than 10%. The assay is highly sensitive and has a working range from 1 to 500 ng/mL for urine and 1 to 250 ng/mL for blood. The assay was further validated with authentic urine and blood specimens obtained from volunteers and coroner's laboratories.

Development of a homogeneous immunoassay for the detection of zolpidem in urine.

Sleep disorders are common conditions that affect about 40 million people in the U.S every year, the most common of which is insomnia, which is characterized by difficulty falling or staying asleep. Zolpidem (Ambien) is a non-benzodiazepine prescription drug that is used to treat insomnia and is often preferred over the commonly used benzodiazepines due to a lesser side effect profile. This is because the non-benzodiazepine binding is more selective to GABA-A receptors versus the non-selective binding of benzodiazepines. With the increasing popularity of non-benzodiazepines, drug abuse and driving-while-impaired cases involving sleep-inducing drugs have risen. Therefore, a highly sensitive and rapid homogeneous immunoassay (EMIT-type assay) has been developed for the detection of zolpidem in urine. The zolpidem antibody is highly specific and does not cross-react with other newer sleep aids such as zopiclone and zaleplon. This assay has a detection limit of 5 ng/mL for zolpidem in urine. Further evaluation of this assay using liquid chromatography-tandem mass spectrometry (LC-MS-MS) analysis of authentic urine samples demonstrated that the accuracy of the assay is greater than 90%. Because this assay is designed to measure the non-conjugated drug in urine, it resulted in simplification for gas chromatography-MS or LC-MS-MS confirmation methods that do not require urine hydrolysis before solid-phase extraction or liquid-liquid extraction.