Buprenorphine and norbuprenorphine quantification in human plasma by simple protein precipitation and ultra-high performance liquid chromatography tandem mass spectrometry

Introduction Compliance with sublingual buprenorphine/naloxone (SL-BUP/NX) is associated with higher abstinence from illicit opioid use. Therapeutic drug monitoring (TDM) has been recommended for adherence monitoring of buprenorphine (BUP) maintenance treatment for opioid use disorder (OUD), but to date there have been no reported clinical applications. In this TDM feasibility study, we investigated BUP assay precision in 15 adults with OUD who had been stabilized on buprenorphine/naloxone. Methods Using solid phase extraction, BUP recovery was contrasted at 100 mMol and 1 Molar of acetic acid wash solution. Precision was determined by applying the condition generating highest recovery using 0.2 ng/mL and 10 ng/mL standards. Four blood samples were drawn to examine the BUP peak and trough plasma concentrations, and BUP elimination rate was estimated. BUP recovery was examined again in a random sample and contrasted with the concentration predicted applying first-order kinetics. Results Higher BUP recovery was achieved with 1 Molar wash (94.3%; p=0.05). Precision ranged from 15–20%. The estimated limit of detection (LoD) and limit of quantitation (LoQ) were 0.02 and 0.069 ng/mL, respectively. BUP peak and trough concentrations were successfully examined, and BUP trough concentrations were replicated confirming steady state. BUP concentrations were predicted at a variance of −7.20% to 1.54 %. Conclusions TDM for BUP maintenance treatment of OUD is feasible, and simple adjustment of the assay conditions enhances BUP recovery.

A highly feasible and reliable ultra-high performance liquid chromatography tandem mass spectrometry method was presented for therapeutic drug monitoring of five anti-schizophrenic drugs (amisulpride, olanzapine, aripiprazole, paliperidone and ziprasidone) simultaneously. To meet the requirements of practical clinical usage (easy handling, high throughput and cost effectiveness), the pretreatment process was simplified (only including protein precipitation and mobile phase dilution steps) and the UPLC separation cycle was set within 6 min. The whole methodology was carefully validated according to the latest international guidelines showing the excellent selectivity, accuracy, precision, applicability and stability. After a 10 month clinical application, a retrospective analysis of 253 positive samples was carried out to investigate conformance with the Arbeitsgemeinschaft für Neuropsychopharmakologie und Pharmakopsychiatrie therapeutic reference range for Chinese patients. The results suggested good consistency for olanzapine, aripiprazole, paliperidone and ziprasidone, while for amisulpride, the plasma concentration level (445.2 ± 231.5 ng/mL) was relatively higher than the recommended range (100-320 ng/mL). We supposed that such phenomenon indicated the necessity of reconstructing a Chinese-specific therapeutic reference range for amisulpride treatment, which would be helpful to improve medication efficiency and safety for Chinese patients.

A new method using ultra-fast liquid chromatography and tandem mass spectrometry (UFLC–MS/MS) was developed for the simultaneous determination of buprenorphine and the metabolites norbuprenorphine, buprenorphine-3β-glucuronide, and norbuprenorphine-3β-glucuronide in plasma and urine. Sample handling, sample preparation and solid-phase extraction procedures were optimized for maximum analyte recovery. All four analytes of interest were quantified by positive ion electrospray ionization tandem mass spectrometry after solid-phase microextraction. The lower limits of quantification in plasma were 1 pg/mL for buprenorphine and buprenorphine glucuronide, and 10 pg/mL for norbuprenorphine and norbuprenorphine glucuronide. The lower limits of quantitation in urine were 10 pg/mL for buprenorphine, norbuprenorphine and their glucuronides. Overall extraction recoveries ranged from 68–100% in both matrices. Interassay precision and accuracy was within 10% for all four analytes in plasma and within 15% in urine. The method was applicable to pharmacokinetic studies of low-dose buprenorphine.