Urinary Pharmacokinetics of Immediate and Controlled Release Oxycodone and its Phase I and II Metabolites using LC-MS/MS

Oxycodone is a schedule II semi-synthetic opioid in the United States that is prescribed for its analgesic effects and has a high potential for abuse. Prescriptions for oxycodone vary based on the dosage and formulation, immediate release (IR) and controlled release (CR). Monitoring oxycodone metabolites is beneficial for forensic casework. The limited studies that involve pharmacokinetics of the urinary excretion of oxycodone metabolites leave a knowledge gap regarding the excretion of conjugated and minor metabolites, pharmacokinetic differences by formulation, and the impact of CYP2D6 activity on the metabolism and excretion of oxycodone. The objectives of this study were to compare urinary excretion of phase I and II metabolites by formulation and investigate if ratio changes over time could be used to predict the time of intake. Subjects (n=7) received a single 10 mg IR tablet of Oxycodone Actavis. A few weeks later the same subjects received a single 10 mg CR tablet of Oxycodone Actavis. During each setting, urine was collected at 0, 0.5, 1, 1.5, 2, 3, 4, 5, 6, 8, 9, 10, 12, 14, 24, 48, and 72 h. Urine samples (100 µL) were diluted with 900 µL internal standard mixture and analyzed on an Acquity UPLC® I-class coupled to a Waters Xevo TQD using a previously validated method. The CYP2D6 phenotypes were categorized as poor metabolizers (PM), intermediate metabolizers (IM), extensive metabolizers (EM), and ultra-rapid metabolizers (UM). Comparisons between IR and CR were performed using two-tailed paired T-test at a significance level of p=0.05. The metabolite ratios showed a general increase over time. Four metabolite to parent ratios were used to predict the time of intake showing that predictions were best at the early time points.

Urine Drug Screening in the Era of Designer Benzodiazepines: Comparison of Three Immunoassay Platforms, LC-QTOF-MS, and LC-MS/MS

ABSTRACT This study investigated the presence of designer benzodiazepines in 35 urine specimens obtained from emergency department patients undergoing urine drug screening. All specimens showed apparent false-positive benzodiazepine screening results (i.e., confirmatory testing using a 19-component LC-MS/MS panel showed no prescribed benzodiazepines at detectable levels). The primary aims were to identify the possible presence of designer benzodiazepines, characterize the reactivity of commercially available screening immunoassays with designer benzodiazepines, and evaluate the risk of inappropriately ruling out designer benzodiazepine use when utilizing common urine drug screening and confirmatory tests. Specimens were obtained from emergency departments of a single US Health system. Following clinically ordered drug screening using Abbott ARCHITECT c assays and lab-developed LC-MS/MS confirmatory testing, additional characterization was performed for investigative purposes. Specifically, urine specimens were screened using two additional assays (Roche cobas c502, Siemens Dimension Vista) and LC-QTOF-MS to identify presumptively positive species, including benzodiazepines and non-benzodiazepines. Finally, targeted, qualitative LC-MS/MS was performed to confirm the presence of 12 designer benzodiazepines. Following benzodiazepine detection using the Abbott ARCHITECT, benzodiazepines were subsequently detected in 28/35 and 35/35 urine specimens, respectively, using Siemens and Roche assays. LC-QTOF-MS showed the presumptive presence of at least one non-FDA approved benzodiazepine in 30/35 specimens: flubromazolam (12/35), flualprazolam (11/35), flubromazepam (2/35), clonazolam (4/35), etizolam (9/35), metizolam (5/35), nitrazepam (1/35), and pyrazolam (1/35). Two or three designer benzodiazepines were detected concurrently in 13/35 specimens. Qualitative LC-MS/MS confirmed the presence of at least one designer benzodiazepine or metabolite in 23/35 specimens, with 3 specimens unavailable for confirmatory testing. Urine benzodiazepine screening assays from three manufacturers were cross-reactive with multiple non-US FDA-approved benzodiazepines. Clinical and forensic toxicology laboratories using traditionally designed LC-MS/MS panels may fail to confirm the presence of non-US FDA-approved benzodiazepines detected by screening assays, risking inappropriate interpretation of screening results as false-positives.

Qua-Alluding to the Past: A Case of Methaqualone Analog Ingestion

Methaqualone, known previously under the brand name Quaalude, is a Schedule I sedative hypnotic drug that may cause neurotoxicity in overdose, characterized by somnolence, hyperreflexia and muscular hyperactivity. We present a case of a 21-year-old male who reportedly ingested methaqualone in addition to insufflation of street cocaine. He subsequently developed hypoxia, hyperreflexia, myoclonus, and altered mental status. His laboratory results were notable for the presence of methemoglobinemia, which was most likely due to a cocaine contaminant. Laboratory analysis of the alleged methaqualone pills identified the substance as SL-164, a dichlorinated methaqualone analog. Urine toxicology results were positive for SL-164 (and presumed metabolites) as well as for cocaine and tetrahydrocannabinol metabolites. The patient was treated with supplemental oxygen and a benzodiazepine (lorazepam) and observed in the Emergency Department (ED) until his symptoms resolved. This case highlights current community access to methaqualone analogs. The case also focuses on laboratory techniques used to identify the methaqualone analog.