Determination of anaprazole in human plasma by LC-MS/MS in pharmacokinetic study

Anaprazole is a proton pump inhibitor clinically used for curing peptic ulcer. A rapid, sensitive and convenient LC-MS/MS method was first established for the determination of anaprazole in human plasma. d₃, ¹³C-anaprazole was used as internal standard (IS). After extraction from human plasma by protein precipitation with acetonitrile, all components were separated on an Extend C₁₈ column (100 mm×4.6 mm, 3.5 μm). The assay was linear over the concentration range of 5.00-3 000 ng·mL^-1 (r² > 0.995). The method was successfully applied to a pharmacokinetic study of 40 mg anaprazole enteric-coated tablets in 14 Chinese healthy volunteers under fasting or high fat diet conditions. C_max was (1 020±435) ng·mL^-1 and AUC_0-t was (2 370±754) h·ng·mL^-1 under fasting condition. And C_max was (538±395) ng·mL^-1 and AUC_0-t was (1 610±650) h·ng·mL^-1 under high fat diet condition. The plasma results suggest that the exposure of anaprazole is reduced by the high fat diet.