Effect of Moisture on the Physical and Chemical Stability of Granulations and Tablets of the Angiotensin Converting Enzyme Inhibitor, Enalapril Maleate

Abstract

Granulations and tablets of enalapril maleate in a lactose matrix were stored in open petri dishes at a range of relative humidities and respective moisture uptakes measured, Extrapolation of the moisture uptake rates measured at the exaggerated humidities yielded a critical humidity, i.e. humidity where the moisture uptake rate is zero and, therefore, least detrimental to the product. Enalapril maleate was reasonably stable at the storage conditions. The hardness of the tablets decreased at all humidities except when stored with silica-gel. The disintegration times were unaffected except at very high humidities. The dissolution profiles of the tablets remained unchanged.