Simple and sensitive determination of menatetrenone and its epoxide metabolite in human plasma.

A simple and rapid quantification method was developed for determining menatetrenone and its epoxide metabolite in human plasma. After a simple protein precipitation with methanol, the analytes were chromatographed on a reversed-phase C(18) column and detected by LC/MS/MS with atmospheric pressure chemical ionization. The coefficient of variation of the assay precision was less than 10.1%, and the accuracy ranged from 98.0 to 106.5%. The limit of detection of menatetrenone and its epoxide was 0.5 and 0.2 ng/ml, respectively. This method was used to simultaneously measure the plasma concentration of menatetrenone and its epoxide metabolite from healthy subjects after a single 30 mg oral dose of menatetrenone.