SPECTROPHOTOMETRIC METHODS FOR SIMULTANEOUS DETERMINATION OF VARDENAFIL AND DAPOXETINE HYDROCHLORIDES IN COMBINED DOSAGE FORM
Mona M. Abdel-Moety,*, Eglal R. Souaya and Ethar A. Soliman
ABSTRACT
Three simple, accurate and sensitive UV-spectrophotometric methods have been developed for simultaneous determination of vardenafil hydrochloride (VAR) and dapoxetine hydrochloride (DAP) in bulk powder and combined dosage form. Method I is based on zero-crossing derivative spectrophotometry. In this method the second derivative (2D) were used for the determination of VAR at zero-crossing wavelength 260.9 nm, while the first derivative (1D) were used for the determination of DAP at zero-crossing wavelength 240.8 nm. Method II is depending on ratio derivative spectrophotometry, the amplitudes in the first derivative of ratio spectra (1DD) were measured at wavelength 241.9 and 238.5 nm for VAR and DAP, respectively.
Method III is dual wavelength method, in this method “the absorbance difference between two points, corresponding to a certain drug, on the mixture spectra is directly proportional to the concentration of the other drug”. At wavelengths 278.1 and 298.4 nm, DAP has equal absorbance values, therefore, these two wavelengths have been used to determine VAR, on similar basis 209.8 and 217.4 nm were selected to determine DAP in the combined formulation. The developed methods were validated in terms of linearity, accuracy, precision, limit of detection, limit of quantification and ruggedness according to ICH guideline. The results obtained by applying the proposed methods were statistically analyzed and compared with those obtained by reported HPLC method showed excellent agreement.
Keywords: Vardenafil hydrochloride; Dapoxetine hydrochloride; Zero-Crossing derivative spectrophotometry; Ratio derivative spectrophotometry; Daul wavelength.
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