Dispersive solid-phase extraction of buprenorphine from biological fluids using metal-organic frameworks and its determination by ultra-performance liquid chromatography.

In this work, various types of metal-organic frameworks were synthesized, and their affinities toward buprenorphine were evaluated using dispersive solid-phase extraction. The extracted buprenorphine was determined by ultra high performance liquid chromatography-ultraviolet detection system. The highest extraction recovery was observed by employing zeolitic imidazole framework-67. Then, a facile and fast extraction method was designed for the extraction and purification of the target drug. Optimization of the extraction method was carried out by the design of experiment approach. A linearity range of 1-1000 µg/L with the limit of detection of 0.15 µg/L and relative standard deviations (50 µg/L, n = 5) of 3.4% was obtained for standard sample analysis. Under optimized experimental and instrumental conditions, the relative recoveries were in the range of 95 to 111%. Eventually, zeolitic imidazole framework-67 was successfully employed for the extraction and determination of buprenorphine in the biological fluids with satisfactory results.

Highly selective extraction and voltammetric determination of the opioid drug buprenorphine via a carbon paste electrode impregnated with nano-sized molecularly imprinted polymer.

An electrochemical sensor for the opioid drug buprenorphine (BUP) is described. Molecularly imprinted polymer nanoparticles (nanoMIP) were prepared and used to modify a carbon paste electrode (CPE). The BUP-imprinted polymer was synthesized using precipitation polymerization. The resulting polymer along with multiwalled carbon nanotubes (MWCNT) was used to fabricate the modified CPE which exhibited an anodic peak at about +0.73 V (vs. Ag/AgCl) for BUP. The MIP on the CPE functions as selective recognition element with an imprinting factor of 5.6. The assay consists of two-steps, viz. analyte extraction at the electrode surface and differential pulse voltammetric determination of BUP. The effects of various parameters on the electrochemical signal were optimized, and the selectivity of the modified CPE over cross reactants was studied. At optimum experimental conditions, the response is linear in the 1 nM to 50 µM BUP concentration range, and the detection limit is 0.6 nM (at S/N = 3). This method was applied to the determination of BUP in spiked urine with acceptable relative standard deviations (3.2-4.4%). Graphical abstract Schematic representation of buprenorphine (BUP) recognition and voltammetric determination at the surface of carbon paste electrode modified with imprinted polymer and carbon nanotubes.

Hollow fiber liquid-phase microextraction combined with ultra-high performance liquid chromatography-tandem mass spectrometry for the simultaneous determination of naloxone, buprenorphine and norbuprenorphine in human plasma.

A hollow fiber liquid phase microextraction (HF-LPME) combined with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed for the extraction and determination of naloxone (NLX), buprenorphine (BP) and its major metabolite norbuprenorphine (NBP) in human plasma. The optimum extraction conditions of HF-LPME were: the porous of polyvinylidene fluoride (PVDF) hollow fiber was full of component solvent (1-octanol/chloroform/toluene, 2/4/4), the pH of donor phase was 8.7, the extraction time was 30min and stirring speed was 1000 revolutions per minute (rpm). The UHPLC-MS/MS method was performed with Waters ACQUITY UPLCTM BEH C18, 50mm×2.1mm, 1.7µm, using methanol-0.2%formic acid as mobile phase with a gradient elution at a flow rate of 0.25mL/min. The target compounds were detected under a tandem quadrupole mass spectrometer in positive electrospray ionization (ESI) mode, then analyzed in multiple reaction monitoring (MRM) mode and the isotope internal standard method was used for quantification. The results showed that linearities were in the range of 0.1-25ng/mL (R>0.996). The limits of detection (LOD) of BP/NBP/NLX were 0.05/0.05/0.025ng/mL and the limits of quantitation (LOQ) of BP/NBP/NLX were 0.1/0.1/0.05ng/mL, respectively. The spiked recoveries were in the range of 92.1-106.0% with relative standard deviation (RSD) values were less than 15%. This method was simple, inexpensive, sensitive and has been successfully used to quantify plasma samples from patients included in a clinical pharmacogenetic study.

Chemical and enzyme-assisted syntheses of norbuprenorphine-3-ß-D-glucuronide.

Norbuprenorphine-3-ß-d-glucuronide (nBPN-3-ß-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.

Development and validation of a highly sensitive GC/MS method for the determination of buprenorphine and nor-buprenorphine in blood.

A sensitive and specific GC/MS method for the determination of buprenorphine (BPN) and its main metabolite nor-buprenorphine (nor-BPN) in blood has been developed, optimized and validated. Sample preparation includes solid-phase extraction of both analytes and their derivatization with acetic anhydride in pyridine. BPN-d4 was used as internal standard for the determination of both analytes. Limits of detection and quantification for BPN and nor-BPN were 0.02 and 0.05 µg/L, respectively. The calibration curves were linear within the dynamic range of each analyte (0.05-30.0 µg/L) with a correlation coefficient higher than 0.996. Absolute recovery ranged from 90.2 to 97.6% for both analytes and their internal standard. Intra- and inter-day accuracy was found to be between -5.40 to 1.73% and -2.45 to 2.80%, respectively, while intra- and inter-day precision were less than 5.8 and 4.7%, for both analytes. The method was applied to real blood samples obtained from patients that follow BPN maintenance program. The developed method can be used in routine every day analysis by clinical and forensic laboratories, for pharmacokinetic studies, for therapeutic drug level monitoring in order to adjust BPN dosage of BPN maintained patients or for the investigation of forensic cases.

[A study in extraction method of buprenorphine in urine].

OBJECTIVE: The extraction method for separating buprenorphine from urine was described. METHODS: Buprenorphine was extracted with chloroform at pH7 or with SPE (extracted by organic support 401 at pH10.8, then eluted with chloroform), finally determined by GC-NPD. RESULTS: The extracted yields of the analyte in specimens were 86.6% by solution-phase extraction and 83.0% by solid-phase extraction (SPE) respectively. CONCLUSION: These two methods are simple and accurate for separating buprenorphine from urine.

Preparation of [11C]buprenorphine--a potential radioligand for the study of the opiate receptor system in vivo.

A method is described for the preparation of [11C]buprenorphine in high specific activity, based on the reaction of N-(de-cyclopropylmethyl)buprenorphine with "no carrier added" [1-11C]cyclopropanecarbonyl chloride followed by reduction with lithium aluminium hydride. The [1-11C]cyclopropanecarbonyl chloride is itself prepared from cyclotron-produced [11C]carbon dioxide. The overall preparation time is 57 min from the end of radionuclide production, and the radiochemical yield is ca 20%, (decay-corrected from [11C]-carbon dioxide). [11C]Buprenorphine has potential as a radioligand for the study of the opiate receptor system in vivo by means of position emission tomography.