Simultaneous UV-Spectrophotometric Estimation of Acetaminophen and Guaiphenesin by Second Order Derivative Method in Combined Pharmaceutical Dosage form

The objective of the study was to develop a simple, accurate, precise and rapid a UV spectrophotometric i.e. Second order derivative method for the determination of acetaminophen and guaiphenesin in combined dosage form i.e. tablets by using methanol as a solvent. The method was further validated by ICH guidelines. The proposed second order derivative method involves the measurement of absorbance of one drug at zero crossing point of other; hence wavelengths 215 nm and 234 nm were selected for the estimation of acetaminophen and guaiphenesin respectively. The linearity of the proposed method was found in the concentration range of 1 to 10 μg /ml (r²= 0.9993) for acetaminophen and 5 to 100 μg /ml (r²= 0.9998) for guaiphenesin respectively. The percentage mean recovery was found to be 99.945 % for acetaminophen and 99.955 % for guaiphenesin respectively. The method was also statistically validated for its linearity, accuracy and precision. Both intra and inter day variations showed less percentage (%) RSD values indicating high grade of precision of this method.