Cross-reactivity of the CEDIA buprenorphine assay in drugs-of-abuse screening: influence of dose and metabolites of opioids

Quantitative Analysis of Buprenorphine, Norbuprenorphine, and Their Glucuronide Metabolites in Human Urine

We present a quantitative clinical LC-MS/MS assay for the simultaneous analysis of buprenorphine, norbuprenorphine, and their glucuronide metabolites in human urine. The assay is based on the direct and hydrolysis-free sample preparation protocol, i.e., dilute and shoot, whereby clarified urine specimens are diluted in internal standard reagent and injected into the LC-MS/MS instrument. The analytical platform employs reversed-phase liquid chromatography for upfront separation and electrospray ionization multiple reaction monitoring MS detection via the triple-quadrupole (TSQ Quantiva) instrument. The assay has a quantitative analytical range of 5 ng/mL-1000 ng/mL represented at seven levels for each of the four analytes. A unique stable isotopically labeled analogue is used as internal standard for each analyte. For high-throughput performance, the assay can be multiplexed between two LC channels.

Analysis of Drugs in Saliva of US Military Veterans Treated for Substance Use Disorders Using Supported Liquid Extraction and Surface-Enhanced Raman Spectral Analysis

According to the Center for Disease Control, there were more than 107,000 US drug overdose deaths in 2021, over 80,000 of which due to opioids. One of the more vulnerable populations is US military veterans. Nearly 250,000 military veterans suffer from substance-related disorders (SRD). For those seeking treatment, buprenorphine is prescribed to help treat opioid use disorder (OUD). Urinalysis is currently used to monitor buprenorphine adherence as well as to detect illicit drug use during treatment. Sometimes sample tampering occurs if patients seek to generate a false positive buprenorphine urine test or mask illicit drugs, both of which can compromise treatment. To address this problem, we have been developing a point-of-care (POC) analyzer that can rapidly measure both medications used for treatment and illicit drugs in patient saliva, ideally in the physi-cian's office. The two-step analyzer employs (1) supported liquid extraction (SLE) to isolate the drugs from the saliva and (2) surface-enhanced Raman spectroscopy (SERS) to detect the drugs. A prototype SLE-SERS-POC analyzer was used to quantify buprenorphine at ng/mL concentrations and identify illicit drugs in less than 1 mL of saliva collected from 20 SRD veterans in less than 20 min. It correctly detected buprenorphine in 19 of 20 samples (18 true positives, 1 true negative and 1 false negative). It also identified 10 other drugs in patient samples: acetaminophen, amphetamine, cannabidiol, cocaethylene, codeine, ibuprofen, methamphetamine, methadone, nicotine, and norbuprenorphine. The prototype analyzer shows evidence of accuracy in measuring treatment medications and relapse to drug use. Further study and development of the system is warranted.

Recent Update on Pretreatment and Analysis Methods of Buprenorphine in Different Matrix

Buprenorphine is one of the most commonly used pain-killing drugs due to its lengthy duration of action and high potency. However, excessive usage of buprenorphine can be harmful to one's health and prolonged use might result in addiction. Additionally, an increasing number of cases have been documented involving the illegal use of buprenorphine. Therefore, a variety of effective and reliable methods for pretreatment and determination of buprenorphine and its main metabolite norbuprenorphine have been established. This review aims to update the current state of pretreatment and detection techniques for buprenorphine and norbuprenorphine from January 2010 to March 2022. Pretreatment methods include several traditional extraction methods, solid-phase extraction, QuECHERS, various micro-extraction techniques, etc. while analytical methods include LC-MS, LC coupled with other detectors, GC-MS, capillary electrophoresis, electrochemical sensors, etc. The pros and cons of various techniques were compared and summarized, and the prospects were provided. HIGHLIGHTSProgress in pretreatment and detection methods for buprenorphine is demonstrated.Pros and cons of different pretreatment and analysis methods are compared.New materials (such as nanomaterials and magnetic materials) used in buprenorphine pretreatment are summarized.Newly emerged environmental-friendly methods are discussed.

Consumption of the Sugar Substitute Stevia Leads to Cross-Reactivity of CEDIA® Buprenorphine II Immunoassay

Buprenorphine is a semisynthetic opioid that is often used in opiate maintenance therapy. For this purpose, regular toxicological analyses of urine samples are mandatory. For fast analytical results, analyses are commonly performed by immunoassay, for example, Thermo Scientific™ CEDIA® Buprenorphine or Buprenorphine II assay. One drawback of immunoassay-based methods is the possible cross-reaction with other substances. Several drugs have already been checked for cross-reactivity to CEDIA® Buprenorphine II immunoassay. In contrast, cross-reactivities have not been checked for any food additives. In the present study, a cross-reaction of CEDIA® Buprenorphine II assay to steviol glucuronide was investigated. Steviol glucuronide is a phase II metabolite of the sugar substitute stevia. For our study, 32 urine samples of patients in rehabilitation centers were collected. These samples were tested positive with the CEDIA® Buprenorphine II immunoassay. These findings were suspicious, because it was highly unlikely that the patients in those institutions had access to buprenorphine. The absence or presence of buprenorphine in urine samples was evaluated by a validated gas chromatography-mass spectrometry method. In order to determine the concentration of steviol glucuronide in urine samples, a liquid chromatography-tandem mass spectrometry method has been developed and fully validated according to the respective guidelines of the German Society of Toxicological and Forensic Chemistry. The cross-reactivity of steviol glucuronide in the CEDIA® Buprenorphine II immunoassay was observed at concentrations above 15,000 µg/L. These findings demonstrate that food additives should also be considered as compounds that may reduce the selectivity of immunoassays and emphasize the importance of confirming implausible results by selective analytical methods.

Comparison of several immunoassays used in drugs of abuse screening: Assessment against gold standard methods and calculation of measurement uncertainty

BACKGROUND

Immunoassays provide simple, powerful and inexpensive screening methods for urine drug screening. Other substances and/or factors may interfere with the test and cause false or positive results. It is essential to understand the differences between methods to be able to evaluate their impact on the results. All evaluated immunoassays were assessed in comparison with GC-MS or LC-MS/MS, which are generally accepted as vigorous confirmation gold standard techniques.

METHODS

CEDIA, DRI, EIA and EMIT II Plus screening immunoassays were evaluated on Beckman-Coulter AU5810 analyser. All results were confirmed using GC-MS or LC-MS/MS methods. Measurement Uncertainty for immunoassays was calculated by using standard deviation multiplied by 1.96 to cover 95% confidence interval of tested samples.

RESULTS

No discrepancy was found between CEDIA and EMIT II Plus for cocaine, methadone, heroin, and benzodiazepines assays. No discrepancy was found between oxycodone DRI assay and Immunalysis enzyme immunoassay (EIA). Cannabinoids EMIT II Plus assay performed better than DRI assay. EMIT II Plus assays for amphetamine and ecstasy performed better than CEDIA amphetamine/ecstasy combined assay. Opiates EMIT II Plus assay performed better than CEDIA assay. Fentanyl Ark EIA method performed slightly better than the DRI method. Buprenorphine CEDIA second-generation assay performed better than CEDIA first-generation assay, EMIT II Plus assay and EMIT II Plus with added Beta-Glucuronidase assay. Measurement Uncertainty for immunoassays was calculated and tabulated.

CONCLUSIONS

This study covered a fundamental gap in available knowledge by evaluating the performance of screening the current new generation of immunoassays methods for drugs of abuse in urine against gold standard methods.

A Novel Enzyme Immunoassay for the Detection of Buprenorphine, Norbuprenorphine and Their Glucuronides in Urine

Buprenorphine is a commonly used opioid in pain therapy as well as in opiate maintenance therapy. Immunoassays are quick and cost-effective methods for the necessary toxicological urine analysis of maintenance therapy patients. In this study a novel enzymatic immunoassay, the Thermo Fisher Scientific CEDIA Buprenorphine II assay (Bup2) was evaluated for the detection of buprenorphine, norbuprenorphine and their conjugated metabolites in human urine samples. The Bup2 assay has a cut-off of 10 ng/mL with ±25% controls, whereas the existing CEDIA Buprenorphine assay (Bup1) has a cut-off of 5 ng/mL and ±40% controls. Both assays were analyzed on a Thermo Scientific Indiko Plus benchtop analyzer. Seven-day precision studies of Bup2 assay demonstrated excellent precision of 7.2-10.6%. No crossover between control samples and the cut-off level were observed. Urine samples of 120 patients undergoing opiate maintenance therapy were collected. Immunoassay results of Bup1 and Bup2 were confirmed by gas chromatography mass spectrometry (GC/MS) for buprenorphine and norbuprenorphine as well as for their glucuronides. Comparison showed a specificity of 0.99 between the Bup2 assay and GC/MS, whereas the Bup1 assay had a specificity 0.70 due to 21 false positive samples. The reason is a known cross-reactivity of the Bup1 assay to opiate compounds. The Bup2 assay revealed one false positive result close to the cut-off value; no specific candidate possibly causing a cross-reaction was detected by GC/MS and liquid chromatography tandem mass-spectrometry (LC/MS/MS) methods. The data presented demonstrate an excellent correlation of the Bup2 assay to GC/MS, showing improved specificity and sensitivity when compared to the Bup1 assay. Thus, the Bup2 assay is highly suitable for urine testing, even for opiate maintenance patients receiving high doses of morphine.

Endogenous Opiates and Behavior: 2016

This paper is the thirty-ninth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2016 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia, stress and social status, tolerance and dependence, learning and memory, eating and drinking, drug abuse and alcohol, sexual activity and hormones, pregnancy, development and endocrinology, mental illness and mood, seizures and neurologic disorders, electrical-related activity and neurophysiology, general activity and locomotion, gastrointestinal, renal and hepatic functions, cardiovascular responses, respiration and thermoregulation, and immunological responses.