A Simple Sample Preparation with HPLC–UV Method for Estimation of Amlodipine from Plasma: Application to Bioequivalence Study

摘要

A simple, rapid and selective method was developed for the estimation of amlodipine from human plasma. Themethod involves a simple protein precipitation techniques using nifedipine as internal standard. Chromatographic separationwas carried out on a reverse phase C18 column using mixture of 50 mM potassium di hydrogen ortho phosphate (pH7.5) and acetonitrile (60:40, v/v) at a flow rate of 1.0 mL/min with UV detection at 239 nm. The retention time of amlodipineand internal standard were 4.12 and 8.31min, respectively. The method was validated and found to be linear inthe range of 0.5-50.0 ng/mL. An open, randomized, two-treatment, two period, single dose crossover, bioequivalencestudy in 24 fasting, healthy, male, volunteers was conducted. After dosing, serial blood samples were collected for the periodof 168.0 h. Various pharmacokinetic parameters including AUC0-t, AUC0-∞, Cmax, Tmax, T1/2, and elimination rateconstant (Kel) were determined from plasma concentration of both formulations of test (Amlodipine 5 mg tablets) and reference(Amlodipine 5 mg tablets). Log transformed values were compared by analysis of variance (ANOVA) followed byclassical 90% confidence interval for Cmax, AUC0-t, AUC0-∞ and was found to be within the range. These results indicatedthat the analytical method was linear, precise and accurate. Test and reference formulation were found to be bioequivalent.