New Bioanalytical HPLC Method for the Determination of Cyproheptadine Hydrochloride in Human Plasma and its Application to Rat Pharmacokinetic Study

Background: Cyproheptadine HCl is a serotonin antagonist and histamine H1 blocker agent. Objective: The objective of the present work was to establish a rapid, sensitive and validated bioanalytical HPLC method using Liquid extraction technique for the determination of Cyproheptadine Hydrochloride in human plasma and its application to rat pharmacokinetic study. Methodology: For development of analytical method, Cyproheptadine HCl was estimated in human plasma after liquid liquid extraction using 20 mm ammonium formate buffer and n-hexane as extracting solvents and Oxcarbazepine as internal standard. For separation of Cyproheptadine HCl from plasma components, Hypersil BDS C18 column (250×4.6 mm i.d, 5µ particle size) at ambient temperature, 224 nm as detection wavelength and (acetonitrile: methanol: 20 mM ammonium formate, pH 5.5 adjusted with 0.2% formic acid 40:10:50, v/v/v) as the mobile phase and at a flow rate of 1 ml/min was used. Results: Newly developed method showed good calibration curve in the concentration range of 100–800 ng/ml with excellent correlation coefficient (r2>0.998) and giving recovery more than 99%. The %RSD for both intraday and interday was less than 2%. Conclusion: The newly developed and validated HPLCPDA method was easy, fast and can be effectively utilized for pharmacokinetic studies in rats after oral administration of Cyproheptadine HCl.