Hydrolysis of Conjugated Metabolites of Buprenorphine II. The Quantitative Enzymatic Hydrolysis of Norbuprenorphine-3- -D-Glucuronide in Human Urine

Pediatric poisoning management: How clinical practice can benefit from forensic approach

Pediatric population represents the most vulnerable and at risk for unintentional poisoning, with children younger than 6 years old accounting for nearly half of poison exposures. Poisoning is a time-dependent emergency. The need to reach a scientific agreement on diagnostic protocol and treatment seems to be crucial to reduce morbidity and mortality. Starting from a buprenorphine pediatric intoxication case, this article highlights the limits and pitfalls of the traditional diagnostic approach. Diagnosis of drug intoxication was achieved after several days when an in-depth diagnostic investigation became necessary and complete forensic toxicological analyses were performed. Results evidenced an alarming lack of an unequivocal diagnostic protocol in case of suspect intoxication in structures not provided with a forensic toxicological service/unit. Collection of biological specimens according to forensic protocols at hospitalization plays a paramount role in the definitive diagnosis of intoxication. A diagnostic algorithm that focuses on medical history and biological specimen collection timing is herein proposed, in order to unify emergency approaches to the suspected poisoned child.

A Rapid Method for the Determination of Buprenorphine and Norbuprenorphine in Urine by UPLC-MS/MS

Background:

Buprenorphine is quite common in the illicit market. Buprenorphinecontaining drug abuse is frequently encountered in patients. The analysis methods used to determine the abuse of buprenorphine and norbuprenorphine are important for forensic science. Buprenorphine is metabolized to norbuprenorphine by the liver.

Objective:

Therefore, the determination of buprenorphine and norbuprenorphine in urine is one of the methods to determine the abuse of buprenorphine.

Methods:

In this study, we developed a precise, simple, and rapid ultra-performance liquid chromatography- tandem mass spectrometer method for the determination of buprenorphine and norbuprenorphine simultaneously.

Results:

The developed method was validated in terms of selectivity and linearity, which was in the range of 9–1800 ng/mL for both buprenorphine and norbuprenorphine. The intra-assay and inter-assay accuracy and precision were found within acceptable limits of the EMA guideline. Lower limits of quantitation were 9 ng/mL for both buprenorphine and norbuprenorphine.

Conclusion:

The developed method was successfully applied for the determination of both analytes in the proficiency testing samples.

Predicting drug-metagenome interactions: Variation in the microbial β-glucuronidase level in the human gut metagenomes

Characterizing the gut microbiota in terms of their capacity to interfere with drug metabolism is necessary to achieve drug efficacy and safety. Although examples of drug-microbiome interactions are well-documented, little has been reported about a computational pipeline for systematically identifying and characterizing bacterial enzymes that process particular classes of drugs. The goal of our study is to develop a computational approach that compiles drugs whose metabolism may be influenced by a particular class of microbial enzymes and that quantifies the variability in the collective level of those enzymes among individuals. The present paper describes this approach, with microbial β-glucuronidases as an example, which break down drug-glucuronide conjugates and reactivate the drugs or their metabolites. We identified 100 medications that may be metabolized by β-glucuronidases from the gut microbiome. These medications included morphine, estrogen, ibuprofen, midazolam, and their structural analogues. The analysis of metagenomic data available through the Sequence Read Archive (SRA) showed that the level of β-glucuronidase in the gut metagenomes was higher in males than in females, which provides a potential explanation for the sex-based differences in efficacy and toxicity for several drugs, reported in previous studies. Our analysis also showed that infant gut metagenomes at birth and 12 months of age have higher levels of β-glucuronidase than the metagenomes of their mothers and the implication of this observed variability was discussed in the context of breastfeeding as well as infant hyperbilirubinemia. Overall, despite important limitations discussed in this paper, our analysis provided useful insights on the role of the human gut metagenome in the variability in drug response among individuals. Importantly, this approach exploits drug and metagenome data available in public databases as well as open-source cheminformatics and bioinformatics tools to predict drug-metagenome interactions.

Synthesis and identification of deschloroketamine metabolites in rats' urine and a quantification method for deschloroketamine and metabolites in rats' serum and brain tissue using liquid chromatography tandem mass spectrometry

Deschloroketamine (2-(methylamino)-2-phenyl-cyclohexanone) is a ketamine analog belonging to a group of dissociative anesthetics, which have been distributed within the illicit market since 2015. However, it was also being sold as 'ketamine' misleading people to believe that they were getting genuine ketamine. Dissociative anesthetics have also come to the attention of the psychiatric field due to their potential properties in the treatment of depression. At present, there is a dearth of information on deschloroketamine related to its metabolism, biodistribution, and its mechanism of action. We have therefore carried out a metabolomics study for deschloroketamine via non-targeted screening of urine samples employing liquid chromatography combined with high-resolution mass spectrometry. We developed and validated a multiple reaction monitoring method using a triple quadrupole instrument to track metabolites of deschloroketamine. Furthermore, significant metabolites of deschloroketamine, (trans-dihydrodeschloroketamine, cis- and trans-dihydronordeschloroketamine, and nordeschloroketamine), were synthesized in-house. The prepared standards were utilized in the developed multiple reaction monitoring method. The quantification method for serum samples provided intra-day accuracy ranging from 86% to 112% with precision of 3% on average. The concentrations of cis/trans-dihydronordeschloroketamines and trans-dihydrodeschloroketamine were lower than 10 ng/mL, nordeschloroketamine and deschloroketamine ranged from 0.5 to 860 ng/mL in real samples. The quantification method for brain tissue provided intra-day accuracy ranging from 80% to 125% with precision of 7% on average. The concentrations of cis/trans-dihydronordeschloroketamines and trans-dihydrodeschloroketamine ranged from 0.5 to 70 ng/g, nordeschloroketamine and deschloroketamine varied from 0.5 to 4700 ng/g in real samples.

Simultaneous determination of opiates, methadone, buprenorphine and metabolites in human urine by superficially porous liquid chromatography tandem mass spectrometry

For monitoring compliance of methadone or buprenorphine maintenance patient, a method for the simultaneous determination of methadone, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), buprenorphine, norbuprenorphine, opiates (morphine, codeine, 6-monoacetylmorphine) in urine by superficially porous liquid chromatography tandem mass spectrometry was developed and validated. After enzyme digestion and liquid-liquid extraction, reverse-phase separation was achieved in 5.2 min and quantification was performed by multiple reaction monitoring. Chromatographic separation was performed at 40 °C on a reversed phase Poroshell column with gradient elution. The mobile phase consisted of water and methanol, each containing 0.1% formic acid, at a flow rate of 0.32 mL/min. Intra-day and inter-day precision were less than 12.1% and accuracy was between -9.8% and 13.7%. Extraction efficiencies were more than 68%. Although ion suppression was detected, deuterated internal standards compensated for these effects. Carryover was minimal, less than 0.20%. All analytes were stable at room temperature for 16 h, 4 °C for 72 h, and after three freeze-thaw cycles. The assay also fulfilled compound identification criteria in accordance with the European Commission Decision 2002/657/EC. We analyzed 62 urine samples from patients received maintenance therapy and found that 54.8% of the patient samples tested were detected for morphine, codeine, or 6-monoacetylmorphine. This method provides a reliable and simultaneous quantification of opiates, maintenance drugs, and their metabolites in urine samples. It facilitates the routine monitoring in individuals prescribed the drug to ensure compliance and help therapeutic process.

Chemical and enzyme-assisted syntheses of norbuprenorphine-3-β-D-glucuronide

Norbuprenorphine-3-β-d-glucuronide (nBPN-3-β-d-G, 1) is a major phase II metabolite of buprenorphine, a pharmaceutical used for the treatment of opioid addiction. The pharmacological activity of compound 1 is not clear because investigations have been limited by the lack of chemically pure, well characterized 1 in sufficient quantities for in vitro and in vivo experiments. This work describes two concise, new methods of synthesis of 1, a chemical and an enzyme-assisted synthesis. The chemical synthesis used a strategy based on a combination of Koenig-Knorr coupling and amino-silyl protection. The enzyme-assisted synthesis used dog liver to convert the substrate norbuprenorphine (nBPN, 2) to 1. Both methods provided 1, characterized by (1)H NMR and tandem mass spectrometry, with purity >96%. The fractional yield of the enzyme-assisted synthesis was greater than that of the chemical synthesis (67% vs 5.3%), but due to larger reaction volumes, the chemical synthesis afforded greater amounts of total 1.

Issues pertaining to the analysis of buprenorphine and its metabolites by gas chromatography-mass spectrometry

"Substitution therapy" and the use of buprenorphine (B) as an agent for treating heroin addiction continue to gain acceptance and have recently been implemented in Taiwan. Mature and widely utilized gas chromatography-mass spectrometry (GC-MS) technology can complement the low cost and highly sensitive immunoassay (IA) approach to facilitate the implementation of analytical tasks supporting compliance monitoring and pharmacokinetic/pharmacogenetic studies. Issues critical to GC-MS analysis of B and norbuprenorphine (NB) (free and as glucuronides), including extraction, hydrolysis, derivatization, and quantitation approaches were studied, followed by comparing the resulting data against those derived from IA and two types of liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods. Commercial solid-phase extraction devices, highly effective for recovering all metabolites, may not be suitable for the analysis of free B and NB; acetyl-derivatization products exhibit the most favorable chromatographic, ion intensity, and cross-contribution characteristics for GC-MS analysis. Evaluation of IA, GC-MS, and LC-MS/MS data obtained in three laboratories has proven the 2-aliquot GC-MS protocol effective for the determination of free B and NB and their glucuronides.

Simultaneous determination of buprenorphine, norbuprenorphine and the enantiomers of methadone and its metabolite (EDDP) in human plasma by liquid chromatography/mass spectrometry

A previously reported enantioselective LC-MS assay for the determination of (R)- and (S)-methadone [Met] and (R)- and (S)-2-ethylidene-1,5-dimethyl-3,3-diphenyl-pyrrolidine [EDDP] (the primary metabolite of Met) has been adapted for use in the simultaneous determination of the plasma concentrations of Met, EDDP, buprenorphine (Bu) and norbuprenorphine (norBu). All of the target compounds were separated within 15 min using an alpha1-acid glycoprotein chiral stationary phase, a mobile phase composed of acetonitrile: ammonium acetate buffer [10 mM, pH 7.0] in a ratio of 18:82 (v/v), a flow rate of 0.9 ml/min at 25 degrees C. Deuterium labeled compounds were used as internal standards [d4-Bu, d3-norBu, (R,S)-d3-Met and (R,S)-d3-EDDP] and linear relationships between peak height ratios and drug concentrations were obtained for Bu and norBu in the range 0.2-12 ng/ml with correlation coefficients greater than 0.999. The relative standard deviations (%R.S.D.) for the intra- and inter-day precision of the method were <4.5% and for accuracy was <4.0%. The method was validated and used to analyze plasma samples obtained from opioid dependent methadone-maintained adults enrolled in a research study.

Measurement of urinary monohydroxy polycyclic aromatic hydrocarbons using automated liquid-liquid extraction and gas chromatography/isotope dilution high-resolution mass spectrometry

A method for the measurement of 24 hydroxylated polycyclic aromatic hydrocarbon metabolites (OH-PAHs) in urine has been developed. The method is based on enzymatic deconjugation, automated liquid-liquid extraction, and gas chromatography/isotope dilution high-resolution mass spectrometry after derivatization of the OH-PAHs to the trimethylsilylated derivatives. The metabolites included in the current method are formed from eight different parent compounds. The limits of detection were below 7 pg/mL when using a sample size of 2 mL of urine, except for 1- and 2-naphthols (18 and 12 pg/mL, respectively). The enzymatic deconjugation efficiency, verified by deconjugation of urine samples spiked with alpha-naphthyl beta-d-glucuronide sodium salt (1-NAP-GLU) and pyrene-1-sulfate potassium salt (1-PYR-SULF), was determined to be 97% for 1-NAP-GLU conjugate and 84% for 1-PYR-SULF. The overall coefficients of variance for six batches of quality control samples (n = 42), was 2.9-11%. Mean method recoveries of the 13C-labeled internal standards were 66-72%, except for 13C6-1-naphthol (46%). The throughput of this method has been determined to be 40 samples per day per analyst. This method is currently applied to epidemiological studies, such as the National Exposure and Nutrition Examination Survey (NHANES), to measure human exposure to PAHs.

New designer drug N-(1-phenylcyclohexyl)-3-ethoxypropanamine (PCEPA): studies on its metabolism and toxicological detection in rat urine using gas chromatographic/mass spectrometric techniques

Studies are described on the metabolism and toxicological detection of the phencyclidine-derived designer drug N-(1-phenylcyclohexyl)-3-ethoxypropanamine (PCEPA) in rat urine using gas chromatographic/mass spectrometric techniques. The identified metabolites indicated that PCEPA was metabolized by N-dealkylation, O-deethylation partially followed by oxidation of the resulting alcohol to the corresponding carboxylic acid, hydroxylation of the cyclohexyl ring at different positions of PCEPA, N-dealkyl PCEPA, O-deethyl PCEPA, and of the corresponding carboxylic acids. Finally, aromatic hydroxylation of PCEPA, the corresponding carboxylic acids, and O-deethyl PCEPA, the latter partially followed by oxidation to the corresponding carboxylic acid and hydroxylation of the cyclohexyl ring could be observed. All metabolites were partially excreted in the conjugated form. The authors' systematic toxicological analysis (STA) procedure using full-scan GC/MS after acid hydrolysis, liquid-liquid extraction, and microwave-assisted acetylation allowed the detection in rat urine of an intake of a common drug users' dose of PCEPA. Assuming a similar metabolism in humans, the STA in human urine should be suitable as proof of intake of PCEPA.