Simple and rapid HPLC method for determination of amlodipine in human serum with fluorescence detection and its use in pharmacokinetic studies.

A fast, sensitive and specific high performance liquid chromatographic method using fluorescence detection is described for analysis of amlodipine in human serum. Amlodipine is extracted from serum by ethyl acetate and involves precolumn derivatization with 4-chloro-7-nitrobenzofurazan (NBD-Cl) and reverse-phase chromatography on C18 column. The mobile phase was sodium phosphate buffer (pH 2.5) containing 1 ml/l triethylamine and methanol at flow rate of 2.8 ml/min. Propranolol was used as internal standard. The standard curve was linear over the range 0.25-16 ng/ml of amlodipine in human serum. The within-day and between-day precision studies showed good reproducibility with coefficients of variation less than 12% for all the analytes. The limit of quantification was 0.25 ng/ml of serum. The method has been applied to a bioequivalence study after administration of 10 mg amlodipine in 12 normal subjects.