Highly sensitive HPLC method for assay of aliskiren in human plasma through derivatization with 1-naphthyl isocyanate using UV detection

A simple and sensitive HPLC method has been developed for the determination of aliskiren in human plasma through derivatization with 1-naphthyl isocyanate. The separation was achieved on a C18 column using a mobile phase consisting of acetonitrile/water/phosphoric acid (45:55:0.01, v/v/v, pH 3.2) in a flow rate of 1 mL/min with UV detection at 230 nm. Caffeine was used as an internal standard. The factors influencing the derivatization reaction yields were carefully studied and optimized. The method was linear over the concentration range of 5–400 ng/mL with a detection limit of 0.5 ng/mL and a limit of quantification of 1.0 ng/mL. The relative standard deviation was less than 4.2% for both intra-day assay and inter-day assay results. No interferences from endogenous compounds were encountered. The percentage recovery was in the range 97.1–98.6%. The method is suitable for routine therapeutic drug monitoring and for pharmacokinetic studies