ABSTRACT
The aim of this work is to determine the anti-inflammatory drug, ibuprofen, and its major degradation product 4-isobutylacetophenone. A stability indicating colorimetric method is developed for the estimation of the intact drug, using the basic dye neutral red, which react at pH 3 with ibuprofen producing orange yellow color extractable with chloroform and its absorbance is measured at 440 nm without interference from the degradation product. Zero order and first order spectra of ibuprofen and its degradation product showed that 4-isobutylacetophenone can be efficiently determined by conventional ultraviolet method at 255 nm and by first derivative method at 265 nm in presence of up to 1 mg% of ibuprofen. The proposed methods were applied for the determination of pure samples, laboratory prepared mixtures and pharmaceutical formulations showing accurate and precise result