Spectrophotometric determination of ramipril (a novel ACE inhibitor) in dosage forms

A simple and sensitive spectrophotometric method has been developed for the determination of ramipril in its dosage forms. The method is based on reac ting the drug with potassium permanganate in alkaline medium whereby a blui sh green colour peaking at 610 nm is produced. The absorbance-concentration plot is rectilinear over the range 0.1-7.5 mug . ml(Sigma1) (r = 0.9992) w ith minimum detectability of 0.05 mug . ml(-1) (1.2 x 10(-7) M). The molar absorptivity was 2.42 x 10(4) L . Mol(-1). cm(-1). The different experiment al parameters affecting the development and stability of the colour were ca refully studied and optimized. The proposed method was further applied to t he determination of ramipril in its dosage forms, whether alone or in combi nation with hydrochlorothiazide. The results obtained were in good agreemen t with those obtained by a reference HPLC method. A proposal of the reactio n pathway was postulated.