MIXED ION-PAIR LIQUID-CHROMATOGRAPHY METHOD FOR THE SIMULTANEOUS ASSAY OF ASCORBIC-ACID, CAFFEINE, CHLORPHENIRAMINE MALEATE, DEXTROMETHORPHAN HBR MONOHYDRATE AND PARACETAMOL IN FRENADOL(TM) SACHETS

The five active drug substances and two of the excipients present in F renadol(TM), a cold medication, were separated. The active drug compon ents dextromethorphan HBr monohydrate, ascorbic acid, caffeine, parace tamol and chlorpheniramine maleate were quantitatively assayed by a mi xed ion pair LC method. The excipients separated were citric acid and maleic acid. The HPLC assay included dual-wavelength detection to simu ltaneously quantify the large concentration of paracetamol and the muc h lower concentration of chlorpheniramine and dextromethorphan. Both t etrabutylammonium hydrogen sulphate (TBA) and pentane sulphonic acid ( PSA) were necessary for resolution of the seven compounds. The TBA was necessary to lessen peak tailing for dextromethorphan and chlorphenir amine, to retain ascorbic acid and to shorten assay time. The pentane sulphonic acid enhanced peak shape for dextromethorphan and chlorpheni ramine. The assay of the active drug substances was validated for use in quality control applications. Validation studies demonstrated that the procedure was accurate, linear, precise, reproducible and rugged. The method conformed to both USP and EC validation guidelines.