Abstract
A simple and sensitive spectrophotometric method for the assay of some cardio-vascular drugs is described. The method is based on the interaction of the drug and p-chloranilic acid (p-CA) to give a stable and intensively coloured ion-pair salt. The drugs used are quinidine sulphate, prenylamine lactate, dipyridamol, hydralazine hydrochloride, tolazoline hydrochloride and pindolol. The optimum experimental conditions for colour development have been studied. Conformity to Beer's law enabled the determination of these drugs in their pharmaceutical preparations. The assay results are in accord with the pharmacopoeal assay results.