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 reacting the drug with potassium permanganate in alkaline medium whereby a bluish green colour peaking at 610 nm is produced. The absorbance-concentration plot is rectilinear over the range 0.1 − 7.5 μg · mlΣ 1 (r = 0.9992) with minimum detectability of 0.05 μg · ml−1 (1.2 × 10−7 M). The molar absorptivity was 2.42 × 104 L · Mol−1 · cm−1. The different experimental parameters affecting the development and stability of the colour were carefully studied and optimized. The proposed method was further applied to the determination of ramipril in its dosage forms, whether alone or in combination with hydrochlorothiazide. The results obtained were in good agreement with those obtained by a reference HPLC method. A proposal of the reaction pathway was postulated.