A stable pharmaceutical composition comprising about 1 wt. % to about 80 wt. % of an
ACE inhibitor or a pharmaceutical acceptable salt thereof, about 1 wt. % to about 70 wt. % of an alkali or
alkaline earth metal carbonate, and about 1 wt. % to about 80 wt. % of
hydroxypropyl cellulose, wherein the
ACE inhibitor is selected from the group consisting of quinapril,
enalapril, spirapril,
ramipril,
perindopril, indolapril,
lisinopril, alacepril,
trandolapril, benazapril, libenzapril, delapril, cilazapril and combinations thereof; wherein the formation of an internal cyclization product, and / or
ester hydrolysis product, and / or oxidation product, has been reduced or eliminated, and the weight percents are based on the total weight of the pharmaceutical composition. The stabilized pharmaceutical compositions of the invention exhibit a number of advantages as follows: (i) the
ACE inhibitor or a pharmaceutical acceptable salt thereof present in the compositions is preserved from degradation; (ii) the compositions exhibit extended shelf-life under normal storage conditions; (iii) the effect of
moisture on the compositions is minimized; (iv) the compositions exhibit minimal, if any, discoloration over a significant period of time; and (v) the compositions exhibit minimal, if any,
instability when employed in the presence of colorants.