Quantitative determination of proguanil HCl in presence of croscarmellose sodium by HPLC using competitor mechanism

A simple, precise and accurate high-performance liquid chromatographic method was developed for estimation of proguanil HCl in presence croscarmellose sodium in bulk and tablet formulation. During analysis a strong interaction between proguanil HCl and croscarmellose sodium was noticed when proguanil HCl in an aqueous solution was spiked with croscarmellose sodium. This interaction leads to retention of drug on the surface of croscarmellose sodium. To overcome the recovery issue an analytical method was set up. This method involves elimination of drug-excipient interaction by competitive inhibition followed by isocratic elution using a mobile phase consisting 0.01% o-phosphoric acid: acetonitrile (55:45v/v). Column used was Qualisil 5 BDS-C18 column (250mm x 4mm i.d., 5 μm particle size) and flow rate was 1mL/min. The detection wavelength was 257 nm. The retention time was found to be 3.821 min. Linearity of the method was 10-70μg/mL. The validated method showed excellent results in terms of accuracy, precision and system suitability.