Quick, simple, and sensitive HPLC method for determination of isradipine in plasma and its application in pharmacokinetic studies

A quick, simple and sensitive HPLC method for the analysis of isradipine (ISRA) in plasma is described using UV detection in the presence of diazepam as internal standard. The method employs a reverse phase C8 column and a mobile phase containing water: acetonitrile (50: 50%, v/v) adjusted to pH 4.0 by glacial acetic acid. Separation of ISRA from plasma is achieved by precipitating plasma proteins with acetonitrile. The lower limit of quantification was 1.0 ng/mL with corresponding retention time of 5.80 min. The suitability of the method for pharmacokinetic studies was verified in rabbits dosed with 0.25 mg IV solution of ISRA and consequently, the relevant pharmacokinetic parameters were determined.