A Sensitive and Rapid LC-MS-MS Method for Simultaneous Determination of Propafenone and Its Active Metabolite 5-Hydroxypropafenone in Human Plasma and Its Application in a Pharmacokinetic Study

A simple and rapid high-performance liquid chromatography tandem mass spectrometry method for the determination of propafenone (PPF) and its active metabolite 5-hydroxypropafenone (5-OHP) in human plasma was developed and validated. This new method was linear and allowed simultaneous quantification of PPF and 5-OHP at a lower level of 0.5 ng/mL. The aliquot of 200 mu L plasma sample was simply treated with 4-fold methanol to deproteinize the plasma. The chromatographic separation was achieved on a Hedera ODS-2C(18) analytical column with the mobile phase of methanol and 5mM ammonium acetate solution containing 0.2% formic acid (pH 3.2) (68: 32, v/v) at a flow rate of 0.4 mL/min. Quantitation of the analytes was achieved by multiple reaction monitoring under positive ionization mode. The method was successfully applied to a pharmacokinetic study of PPF and 5-OHP in healthy Chinese volunteers. After oral administration of a single dose of 425 mg PPF hydrochloride sustained-release capsule, the maximum peak plasma concentration (C-max) of PPF was 210.9 +/- 141.9 ng/mL with a T-max of 6 +/- 1 h, the C-max of 5-OHP was 129.6 +/- 65.4 ng/mL with a Tmax of 7 +/- 2 h. The area under plasma concentration-time curve (AUC(0-36)) of PPF was 1610 +/- 1309 ng . h/mL with a t(1/2) of 4.6 +/- 1.1 h, the AUC(0-36) of 5-OHP was 1446 +/- 754 ng . h/mL with a t(1/2) of 7.6 +/- 1.6 h.