Bioanalytical Method Development and Validation of Cilnidipine and Metoprolol Succinate by RP-HPLC: Its Pharmacokinetic Application

Abstract

Background: Cilnidipine and Metoprolol Succinate are antihypertensive agents used in the treatment of hypertension. Methods: A pharmacokinetic study of Cilnidipine and Metoprolol Succinate in rat plasma was carried out using the chromatographic method. Methods: The chromatographic method involved a reverse phase C18 column, using acetonitrile and pH 4.0 water in the ratio of 80:20 v/v as mobile phase, a flow rate of 1.2 ml/min, and UV detection at 231 nm. In-vivo pharmacokinetic studies were performed on rats. Rats were treated with Cilnidipine (1mg/kg) and Metoprolol Succinate (1 mg/kg) orally, and blood samples were collected at 0, 0.5, 1, 2, 4, 6, 8, 12 and 24 h post-treatment. Results: The retention time of Plasma, Cilnidipine and Metoprolol Succinate was found to be 2.3, 3.1 and 5.5 min, respectively. Linearity was acceptable in the concentration range of 2-10 and 10- 50 for Cilnidipine and Metoprolol Succinate, respectively. The intra-day and inter-day variances were found to be less than 2. The mean recovery of Cilnidipine and Metoprolol Succinate was 100.12 and 100.15, respectively. The assay was successfully applied to a pharmacokinetic study in rat after oral administration. After oral administration, maximal concentration (Cmax) of Cilnidipine and Metoprolol Succinate was found to be 460.01 and 642.13 (μg g/mL), and the halflife was found at 2.0 and 3.904 hours, respectively. Conclusion: The present method was successfully applied to the pharmacokinetic study of Cilnidipine and Metoprolol Succinate in rat plasma after oral administration.