UV Spectrophotometric Determination of Paracetamol in Presence of Drotaverine Hydrochloride

Objective: The aim of this study is to develop three simple, specific and accurate spectrophotometric methods manipulating ratio spectra for the determination of paracetamol in binary mixture with drotaverine hydrochloride in tablet dosage form. Methods: In these methods, the absorption spectra of paracetamol were divided by 8 μg/ml of drotaverine hydrochloride to get the ratio spectra. In the first method (ratio difference), the difference in peak amplitudes of the ratio spectra were measured at 262 and 272 nm. The second method is a ratio subtraction which is based on determination of paracetamol at 248 nm after subtraction of interference exerted by drotaverine hydrochloride. In the third method (mean centering), the mean centered values of the ratio spectra were measured at 262 nm. Results: The proposed methods were accurate, precise and selective for determination of paracetamol in presence of drotaverine hydrochloride in pure form and in pharmaceutical dosage forms. Beer’s law was obeyed in the concentration range of 1–10 μg/ml in all methods. Conclusion: The developed methods were used to determine the studied drug in bulk powder, laboratory prepared mixtures and pharmaceutical dosage form with good accuracy and precision. All methods were validated according to ICH guidelines and the results obtained were statistically compared to those obtained from a reported method and were found to be in good agreement.