Ecofriendly LC-MS/MS and TLC-densitometric methods for simultaneous quantitative assay and monitoring of BEGEV regimen, in vivo pharmacokinetic study application.

To date no analytical method has been developed for the determination of the BEGEV regimen and no study has investigated the kinetic interaction between the drugs, to give us priorities for further clinical study, so two rapid, accurate, sensitive and ecofriendly chromatographic methods were developed for the simultaneous determination of bendamustine (BEN), gemcitabine (GEM) and vinorelbine (VIB) using sildenafil (SIL) as an internal standard (IS) for the purpose of an in vivo pharmacokinetics study in rats. Firstly, the LC-MS/MS method was performed using a mixture of methanol and a 0.1% aqueous solution of formic acid as the mobile phase on a ZORBAX Eclipse Plus C 18 (4.6 mm × 150 mm, 5 μm) column as the stationary phase. BEN, GEM and VIB were ionized by positive ions and detected in the multi-reaction monitoring (MRM) mode using precursor → products of m / z 358.20 → 228.25 for BEN, m / z 264.05 → 112.15 for GEM, m / z 779.55 → 122.20 for VIB and m / z 475.00 → 58.35 for SIL. Secondly, TLC-densitometry was applied on TLC silica gel plates using methanol : ethyl acetate (8 : 2, v/v) as the developing system when the separated peaks were scanned at 280 nm. FDA guidelines were followed for validation of the proposed methods, which presented acceptable ranges; then they were applied for an in vivo study in rats with a quantitative determination of each drug after single or combined administration for an investigation of any suspected drug-drug interaction, and all pharmacokinetic parameters were calculated for therapeutic drug monitoring of those drugs. Green analytical chemistry principles were considered during all the procedural steps to ensure the greenness and the safety of the methods, which were evaluated using four assessment tools, eco-scale assessment, the national environmental method index (NEMI), the green analytical procedure index (GAPI) and the analytical greenness metric approach (AGREE), and the results were satisfactory.