LC–MS/MS method for simultaneous determination of ramelteon and its metabolite M‐II in human plasma: Application to a clinical pharmacokinetic study in healthy Chinese volunteers

摘要

Abstract A sensitive liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) method was developed and validated for the simultaneous determination of ramelteon and its active metabolite M‐II in human plasma. After extraction from 200?μL of plasma by protein precipitation, the analytes and internal standard (IS) diazepam were separated on a Hedera ODS‐2 (5?μm, 150?×?2.1?mm) column with a mobile phase consisted of methanol–0.1% formic acid in 10?m m ammonium acetate solution (85:15, v/v) delivered at a flow rate of 0.5?mL/min. Mass spectrometric detection was operated in positive multiple reaction monitoring mode. The calibration curves were linear over the concentration range of 0.0500–30.0?ng/mL for ramelteon and 1.00–250?ng/mL for M‐II, respectively. This method was successfully applied to a clinical pharmacokinetic study in healthy Chinese volunteers after a single oral administration of ramelteon. The maximum plasma concentration ( C max ), the time to the C max and the elimination half‐life for ramelteon were 4.50?±?4.64ng/mL, 0.8?±?0.4h and 1.0?±?0.9?h, respectively, and for M‐II were 136?±?36?ng/mL, 1.1?±?0.5?h, 2.1?±?0.4?h, respectively.