Hydrolysis of conjugated metabolites of buprenorphine. I. The quantitative enzymatic hydrolysis of buprenorphine-3-beta-D-glucuronide in human urine

Stability and Hydrolysis of Desomorphine-Glucuronide

Desomorphine, the principal opioid in Krokodil, has an analgesic potency approximately ten-times that of morphine. Similar to other opioids, during phase II metabolism it undergoes conjugation with glucuronic acid to form desomorphine-glucuronide. Although hydrolysis of conjugated species is sometimes required prior to analysis, desomorphine-glucuronide has not been fully investigated. In this study, six hydrolysis procedures were optimized and evaluated. Deconjugation efficiencies using chemical and enzymatic hydrolysis were evaluated and stability in aqueous solution was assessed. Acid hydrolysis was compared with five β-glucuronidase sources (BGTurbo™, IMCSzyme™, Escherichia coli, Helix pomatia and Patella vulgata). At optimal conditions, each hydrolysis method produced complete hydrolysis (≥96%). However, under simulated challenging conditions, P. vulgata was the most efficient β-glucuronidase for the hydrolysis of desomorphine-glucuronide. Both BGTurbo™ and IMCSzyme™ offered fast hydrolysis with no need for sample cleanup prior to liquid chromatography-quadrupole/time of flight-mass spectrometry (LC-Q/TOF-MS) analysis. Hydrolysates using E. coli, H. pomatia and P. vulgata underwent additional sample treatment using β-Gone™ cartridges. Additionally, the stability of free and conjugated drug was evaluated at elevated temperature (60°C) in aqueous solutions between pH 4 and 10. No degradation was observed for either desomorphine or desomorphine-glucuronide under any of the conditions tested.

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.

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.

The development and application of a rapid gas chromatography-mass spectrometry method to monitor buprenorphine withdrawal protocols

There are several drug therapies that can be used to treat opiate abuse. One such treatment that is currently gaining wide acceptance is the use of the combined agonist/antagonist drug buprenorphine. As with all long-term treatments, there is a potential for compliance issues to arise, which establishes the need for a technique to facilitate the monitoring of individuals prescribed buprenorphine. One such method has been developed and applied to the routine monitoring of buprenorphine and its primary metabolite in urine. The method was found to be sensitive (limits of detection of 1.0 ng/mL for both buprenorphine and norbuprenorphine), reproducible and linear up to 2000 ng/mL. This article describes the application of this method to the analysis of specimens collected from subjects prescribed a reducing low-dose buprenorphine regimen (10.0-0.4 mg per day) for acute opiate detoxification. A significant relationship between the daily dose and the mean creatinine-corrected concentration of buprenorphine in the urine was observed, together with a relatively stable relationship between the ratio of the urinary concentrations of norbuprenorphine to buprenorphine across the dose range studied.

Buprenorphine in the treatment of opiate dependence: its pharmacology and social context of use in the U.S

Buprenorphine's physiological effects are produced when it attaches to specific opiate receptors that are designated mu, kappa, or delta. Buprenorphine, a partial agonist at the mu receptor and an antagonist at the kappa receptor, produces typical morphine-like effects at low doses. At higher doses, it produces opiate effects that are less than those of full opiate agonists. Knowledge of the physiological effects of opiate receptors and the way they interact with opiate agonists, partial opiate agonists, and opiate antagonists is fundamental to understanding the safety and efficacy of buprenorphine in treatment of pain and opiate addiction. Knowledge of the historical and social context of opiate agonist treatment of opiate dependence is fundamental to understanding how nonpharmacological factors may limit the clinical adoption and utility of a safe and effective medication in treatment of opiate dependence. This article reviews the pharmacology of sublingual buprenorphine and the historical context of opiate agonist therapy; delineates classes of opiate receptors and their interaction with opiate agonists, partial agonists, and antagonists; and describes the commercially available pharmaceutical formulations of buprenorphine. It focuses on sublingual buprenorphine tablets, Subutex and Suboxone, the FDA-approved formulations of buprenorphine for treatment of opiate dependence. Sublingual buprenorphine, and the combination of sublingual buprenorphine/naloxone, have unique pharmacological properties that make them a logical first-line intervention in the treatment of opioid dependence.

Development and validation of a gas chromatography–mass spectrometry method for the simultaneous determination of buprenorphine, flunitrazepam and their metabolites in rat plasma: application to the pharmacokinetic study

Buprenorphine (BUP), a synthetic opioid analgesic, is frequently abused alone, and in association with benzodiazepines. Fatalities involving buprenorphine alone seem very unusual while its association with benzodiazepines, such as flunitrazepam (FNZ), has been reported to result in severe respiratory depression and death. The quantitative relationship between these drugs remain, however, uncertain. Our objective was to develop an analytical method that could be used as a means to study and explore, in animals, the toxicity and pharmacological interaction mechanisms between buprenorphine, flunitrazepam and their active metabolites. A procedure based on gas chromatography-mass spectrometry (GC-MS) is described for the simultaneous analysis of buprenorphine, norbuprenorphine (NBUP), flunitrazepam, N-desmethylflunitrazepam (N-DMFNZ) and 7-aminoflunitrazepam (7-AFNZ) in rat plasma. The method was set up and adapted for the analysis of small plasma samples taken from rats. Plasma samples were extracted by liquid-liquid extraction using Toxi-tubes A. Extracted compounds were derivatized with N,O-bis-(trimethylsilyl)trifluoroacetamide (BSTFA), using trimethylchlorosilane (TMCS) as a catalyst. They were then separated by GC on a crosslinked 5% phenyl-methylpolysiloxane analytical column and determined by a quadrupole mass spectrometer detector operated under selected ion monitoring mode. Excellent linearity was found between 0.125 and 25 ng/microl plasma for BUP, 0.125 and 12.5 ng/microl for NBUP and N-DMFNZ, 0.125 and 5 ng/microl for FNZ, and between 0.025 and 50 ng/microl for 7-AFNZ. The limit of quantification was 0.025 ng/microl plasma for 7-AFNZ and 0.125 ng/microl for the four other compounds. A good reproducibility (intra-assay CV=0.32-11.69%; inter-assay CV=0.63-9.55%) and accuracy (intra-assay error=2.58-12.73%; inter-assay error=0.83-11.07%) were attained. Recoveries were 71, 67 and 81%, for BUP, FNZ and N-DMFNZ, respectively, and 51% for NBUP and 7-AFNZ, with CV ranging from 5.4 to 13.9%, and were concentration-independent. The GC-MS method was successfully applied to the pharmacokinetic study of BUP, NBUP, FNZ, DMFNZ and 7-AFNZ in rats, after administration of BUP and FNZ.