On-line fully automated solid-phase extraction—liquid chromatography analysis of 1,2-dihydro-4-(1,2-dihydro-2-oxo-1-pyridyl)-2,2-dimethyl-1-oxonaphthalene-6-carbonitrile (UR-8225), a new potassium channel opener, in plasma samples

Abstract A fully automated reversed-phase HPLC method for pharmacokinetic studies was developed for the determination in plasma samples of 1,2-dihydro-4-(1,2-dihydro-2-oxo-1-pyridyl)-2,2-dimethyl-1-oxonaphthalene-6-carbonitrile (compound I), a new potassium channel opener. On-line solid-phase extraction was performed with disposable C 18 cartridges. After clean up, the samples were eluted and transferred onto an RP-18 analytical column, where separation was performed with a mobile phase of acetonitrile—10 m M di- n -butylamine phosphate (28:72, v/v). Ultraviolet absorbance detection was used at 236 nm. The detector response was linear in the range 25–2500 ng/ml, and the lowest limit of quantitation was determined at 2.5 ng/ml. The inter-day variability was