Development and Validation of the UV Spectrophotometric Method for Simultaneous Determination of Paracetamol and Pseudoephedrine in Bulk and Combined Tablet Dosage Form

Paracetamol (PARA) and Pseudoephedrine (PSE) are co-formulated drugs that and widely used over the world for the treatment of symptoms associated with common cold. In the present study a specific, rapid and simple UV spectrophotometric method with good sensitivity was developed and validated for the simultaneous quantification of PARA and PSE in bulk and tablet dosage form using methanol as diluent. This method is based on the direct measurement of absorbance at 248 nm wavelength for PARA solution, whereas dual-wavelength absorption measurement is applied for PSE solution (i.e. subtraction of absorbance at 217 nm from that at 201 nm, in which PARA absorbance subtraction is equal to zero). The calibration curves were linear (R-2 = 0.9988 and 0.9976 for PARA and PSE, respectively) in a concentrations range of 2 - 10 mu g/mL for both drugs. Limit of detection is LOD = 0.4159 mu g/mL and 0.29679 mu g/mL and the limit of quantification is LOQ = 1.26 mu g/mL and 0.8994 mu g/mL for PARA and PSE, respectively. The RSD% values for all levels of precision (repeatability, intra-day and inter-day) are within the specified limit for both drugs. The accuracy of PARA determination was ascertained by standard addition method, and the percentage recovery for 50, 100, and 150 % of standard were 97.93, 100, and 101.39%, respectively (RSD% = 1.7). The accuracy of PSE determination was studied by percentage recovery (n = 3), and the results were 100.7, 101.16, and 99.57% (RSD% = 0.6648). The proposed spectrophotometric method was successfully applied to the analysis of commercial tablets and the obtained results were satisfactory.