Quantitative determination of dipyridamole in human plasma by high-performance liquid chromatography-tandem mass spectrometry and its application to a pharmacokinetic study.

Dipyridamole is a classic platelet inhibitor which has been a key medicine in clinical therapy of thrombosis and cerebrovascular disease. A rapid, selective and convenient method using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed for determination of dipyridamole in human plasma. After protein precipitation of 200 microL plasma with methanol, dipyridamole and diazepam (internal standard) were chromatographed on an Ultimate XB-C(18) (50 x 2.1 mm i.d, 3 microm) column with the mobile phase consisting of methanol-ammonium acetate (5 mM; 80 : 20, v/v) at a flow rate of 0.25 mL/min. The detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring mode via positive eletrospray ionization source (ESI(+)). The retention times of dipyridamole and diazepam were 1.4 and 1.2 min, respectively. The method was validated over a concentration range of 0.0180-4.50 microg/mL (r(2) > or = 0.99) with a lower limit of quantitation (LLOQ) of 0.0180 microg/mL for dipyridamole. The intra- and inter-day precisions (RSD) of the assay at all three QC levels were 1.6-12.7% with an accuracy (RE) of -4.3-1.9%, which meets the requirements of the FDA guidance. The HPLC-MS/MS method herein described was proved to be suitable for pharmacokinetic study of sustained-release dipyridamole tablet in volunteers after oral administration.