DETERMINATION OF DUP-128, AN ACAT INHIBITOR AND ITS SULFOXIDE AND SULFONE METABOLITES IN HUMAN PLASMA BY LIQUID-CHROMATOGRAPHY

A sensitive and specific high-performance liquid chromatographic (HPLC ) method with fluorescence detection was developed for the simultaneou s determination of DuP 128 henyl-1H-imidazol-2-ylthio)pentyl]-N-hepthy lurea), an ACAT inhibitor, its sulphone metabolite (XB277), and the se parate determination of sulphoxide metabolite (XC164) in human plasma. After deproteinizing plasma samples with acetonitrile, the organic la yer, created by adding approximately 0.25 g of NaCl, was removed, evap orated to dryness, and the residue then reconstituted with 400 mu l of acetonitrile. The acetonitrile layer was washed with 5 ml of hexane a nd then 50 mu l was injected into the HPLC. DuP 128 and XB277 were sim ultaneously quantified using a YMC basic column and fluorescence detec tion (lambda(Ex) = 270 nm and lambda(Em) = 385 nm). XC164 was quantifi ed using a Waters mu Bondpack C-18 reversed-phase column and fluoresce nce detection (lambda(Ex) = 270 nm and lambda(Em) = 365 nm). The relat ionship between the peak height and plasma concentrations best fit a p ower curve and showed an average Correlation coefficient of >0.99 over a concentration range of 1-200 ng ml(-1) for DuP 128 and XC164 and 2. 5-200 ng ml(-1) for XB277. Good intraday and interday assay precisions (RSD <10%) and accuracy (<14%) for all three compounds were observed. The methods were sufficiently sensitive and selective to quantify pla sma concentrations of DuP 128 and its sulphoxide and sulphone metaboli tes after oral administration of single or multiple dose(s) of >350 mg of DuP 128 to healthy subjects.