SEPARATION AND ASSAY OF FOUR ANTIHISTAMINE DRUGS DIPHENHYDRAMINE, CHLORPHENIRAMINE, CYPROHEPTADINE AND FEXOFENADINE IN PHARMACEUTICAL FORMS BY A SINGLE HPLC METHOD

Objective: The objective of this study was to develop and validate a single HPLC method, in order to separate and assay four antihistamine drugs diphenhydramine, chlorpheniramine, cyproheptadine and fexofenadine in pharmaceutical forms. This method was a practical additional choice in quality control laboratories.Methods: The chromatographic conditions comprised of a classical C18-type stationary phase (150 × 4.6 mm, 5μ), with a mobile phase consisting of, 2.5g of sodium octane sulfonic acid in a mixture of 500 ml of deionized water and 500 ml of acetonitrile, and apparent pH of 2.0 was adjusted with phosphoric acid. The flow rate was 1 ml/min; the detection wavelengths were at 220 nm, 230 nm, 265 nm and 254 nm for diphenhydramine, chlorpheniramine, cyproheptadine and fexofenadine respectively. The temperature was ambient temperature.Results: The method was validated for linearity with correlation coefficients very close to one, the accuracy with mean recovery values between 95.0-105.0%, precision with relative standard deviations of the calculated concentrations less than 5.0% and specificity in the presence of degradation products. Then it was used successfully to separate a mixture of them and to assay these drugs in pharmaceutical forms purchased from Syria.Conclusion: The results presented in this paper showed that the developed method was simple and applicable, for the separation and determination of the four drugs in their pharmaceutical forms