Spectrodensitometric Determination of Certain Pharmaceutical Binary Mixtures Containing Angiotensin Converting Enzyme Inhibitors and Hydrochlorothiazide

A validated HPTLC method was developed for the simultaneous determination of three angiotensin converting enzyme inhibitors namely enalapril maleate, moexipril HCl, and ramipril HCl, in binary mixture with hydrochlorothiazide. Separation was achieved on silica gel 60 F254 HPTLC plates using mobile phases: as chloroform- ethylacetate- methanol (10:1:5 v/v/v) for enalapril maleate : hydrochlorothiazide (Rf: 0.27: 0.67); ethylacetate-chloroformglacial acetic acid (8:2:0.2 v/v/v) for moexipril HCl: hydrochlorothiazide (Rf : 0.15 : 0.45); and benzene- methanol- glacial acetic acid (8:2.5:0.4 v/v/v) for ramipril HCl : hydrochlorothiazide (Rf: 0.50: 0.65). Measurements were recorded with UV densitometry at 223, 216 and 210 nm for the simultaneous determination of the three binary mixtures of enalapril maleate, moexipril HCl, and ramipril HCl each with hydrochlorothiazide, respectively. The proposed method was validated according to ICH and was found to be specific, accurate, precise and robust. It was also successfully applied to the simultaneous determination of EN; RAM each with HCT in tablet dosage form without interference from common excipients.