A chiral LC‐MS/MS method for the enantioselective determination of R‐(+)‐ and S‐(–)‐pantoprazole in human plasma and its application to a pharmacokinetic study of S‐(–)‐pantoprazole sodium injection

Abstract

Pantoprazole, a proton pump inhibitor, is clinically used for the treatment of peptic diseases. An enantioselective LC-MS/MS method was developed and validated for the simultaneous determination of pantoprazole enantiomers in human plasma. Pantoprazole enantiomers and the internal standard were extracted from plasma using acetonitrile. Chiral separation was carried on a Chiralpak IE column using the mobile phase consisted of 10 mm ammonium acetate solution containing 0.1% acetic acid-acetonitrile (28 : 72, v/v). MS analysis was performed on an API 4000 mass spectrometer. Multiple reactions monitoring transitions of m/z 384.1→200.1 and 390.1→206.0 were used to quantify pantoprazole enantiomers and internal standard, respectively. For each enantiomer, no apparent matrix effect was found, the calibration curve was linear over 5.00-10,000 ng/mL, the intra- and inter-day precisions were below 10.0%, and the accuracy was within the range of -5.6% to 0.6%. This method was applied to the stereoselective pharmacokinetic studies in human after intravenous administration of S-(-)-pantoprazole sodium injections. No chiral inversion was observed during sample storage, preparation procedure and analysis. While R-(+)-pantoprazole was detected in human plasma with a slightly high concentration, which implied that S-(-)-pantoprazole may convert to R-(+)-pantoprazole in some subjects.

Stereoselective pharmacokinetics of (R)‐(+)‐ and (S)‐(−)‐rabeprazole in human using chiral LC‐MS/MS after administration of rabeprazole sodium enteric‐coated tablet

“…The decision factors of chiral separation and analysis were the selection of chiral columns and the composition of the mobile phase . We attempted to separate (R)‐(+)‐ and (S)‐(−)‐rabeprazole on a Chiralpak IE column.…”

“…Fortunately, the Chiralpak IC column, with cellulose derivative immobilized stationary phase, has been successfully used to separate rabeprazole enantiomers using an analytical run time of 8 minutes. The use of 10 mM ammonium acetate keeps the stability of aqueous phase and ensures the reproducibility of retention time . The aqueous phase added 0.2% acetic acid enhanced ionization and improved sensitivity, which also results in a shorter analytical run time .…”

“…Methods used to evaluate the matrix effect followed the local standard operating procedures. Two sets of samples at concentrations of 1.20 and 320 ng·mL −1 were prepared to evaluate the matrix effect of each enantiomer and IS.…”

“…The chiral inversion of (R)‐(+)‐ and (S)‐(−)‐rabeprazole at low and high concentrations (1.20 and 320 ng·mL −1 ) are evaluated by making up mixtures with R/S ((R)‐(+)−/(S)‐(−)‐rabeprazole) ratios at 1:0 and 0:1. These samples were analyzed using the chiral LC‐MS/MS method at all of the abovementioned storage and handling conditions by detecting the appearance of the corresponding enantiomer …”

“…Carryover was investigated by comparing the peak area at the retention time of the analytes and the IS in double blank sample immediately following the injection of the upper limit of quantification (400 ng·mL −1 ) to that of the LLOQ sample. The value of carryover should be no more than 20% of analytes and 5% for the IS …”