The simultaneous assay of triprolidine, pseudoephedrine and dextromethorphan in combined preparations by...

Difference spectrophotometric procedures are described for the assay of triprolidine hydrochloride, dextromethorphan hydrobromide and pseudoephedrine hydrochloride in Actifed preparations. Triprolidine is assayed by the measurement of the difference absorbance at 301 nm between equimolar solutions of the sample extract in 0.1 M sulphuric acid and 0.1 M sodium hydroxide in ethanol (20% v/v). Dextromethorphan and pseudoephedrine are assayed by measurement of the amplitudes in the second and fourth derivative spectra of the difference absorption spectrum of the sample solutions. The measured values are proportional to the concentrations of the drugs. The accuracy, precision and selectivity of the procedures are discussed. Applications of the assay are described for Actifed Compound Linctus, Actifed Syrup and Actifed Tablets.