A simple method for determination of losartan in human plasma by HPLC with fluorescence detection and its application in a pharmacokinetic study

In this paper we describe an easy and inexpensive bioanalytical method to quantify losartan in human plasma samples (0.25 mL). The method involves a simple, one-step extraction procedure by pro-tein precipitation. Chromatographic separation of the compound was achieved with a Bondapak Phenyl column eluted with a mixture of acetonitrile and 0.025 potassium dihydrogen phosphate solution pH 2.2 (65:35 v/v) and detected with fluorescence detector at 250 nm and 375 nm as excitation and emission wave-lengths, respectively. The method was linear in the range of 10-1000 ng/mL. The coefficient of variation for the inter-day and intra-day assay were found to be less than 11%. In order to demonstrate the useful-ness of this method, oral pharmacokinetics of losartan was studied in healthy volunteers after administra-tion of 100 mg. The pharmacokinetic results were in agree with previous reports. It is concluded that the method herein reported is suitable for determination of plasma levels of losartan, offering some advan-tages related to small plasma volume, economical reagents and instrumentation, as well as less laborious procedures.