Quantitative analysis of Amoxicillin and Dicloxacillin in Combined Dosage Form by First Derivative and Simultaneous Equation Method in Application to the determination of Content Uniformity

Two simple, accurate and precise spectrophotometric methods have been developed for the simultaneous estimation of Amoxicillin and Dicloxacillin. Method A was quantitative determination of Amoxicillin and Dicloxacillin by First Order Derivative zero crossing method. The first order derivative absorption at 231.02 nm (zero cross point of Dicloxacillin) was used for Amoxicillin and 246.26nm (zero cross point of Amoxicillin) for Dicloxacillin. Both the drugs obeyed the limit 15-35µg/ml (correlation coefficient r 2 <1). No interference was found between the both determined constituents and those of matrix. Method B was developed for estimation of content uniformity of Amoxicillin and Dicloxaciliin in its combined tablet dosage form. The method involves solving the simultaneous equation using 245nm and 227nm as two wavelengths for Amoxicillin and Dicloxacillin respectively. From the results, it was concluded that all brands are within the limits of content uniformity (85-115%). 0.1 N sodium hydroxide was used as a solvent for both methods. Developed method was employed to determine the Amoxicillin and Dicloxacillin content in ten individual capsule units of four marketed formulations. Both the methods were validated statistically and recovery studies were carried out to confirm the accuracy of the methods.