Redox methods validation of paracetamol and ascorbic acid in pharmaceutical preparations

The contents of active substances were determined in a preparation TP-4 (tablets) containing paracetamol, ascorbic acid, caffeine and phenylephrine hydrochloride. For the determination of paracetamol and ascorbic acid a non-specific (cerometric and titration of 2,6-dichloroindophenol) method based on a redox reaction was used. Validation of the methods, performed on model mixtures, proved those methods to be accurate, precise, reproducible and linear within the range from 50% to 150% of the amount declared in the preparation. The content of paracetamol and ascorbic acid in TP-4, Thompayrin, Panadol Extra, Ring N, Polopiryna C, Efferalgan Vitamin C and Vitaminum C 0.2 satisfies the FP V demands (+/- 10% of the declared amount).