Experiment and Computation of Solubility and Dissolution Properties for Enalapril Maleate and Its Intermediate in Pure Solvents

Abstract

The object is to research the solid–liquid phase of enalapril maleate and its intermediate enalapril hydride in pure solvent. Within the investigated temperature range, the mole fraction solubility data in the selected solvents increase with the increasing temperature. The solubility of enalapril hydride in different solvents decreases according to the order ethyl acetate > acetone > ethanol > n-octanol > isopropanol > acetonitrile, while enalapril maleate obeys the order ethyl acetate > acetone > ethanol > acetonitrile > n-octanol > isopropanol. The experimental solubility data of enalapril hydride and enalapril maleate in those solvents were correlated by the modified Apelblat equation, Buchowski–Ksiazaczak λh equation, and Wilson equation. The maximum values of root-mean-square deviation (RMSD) and relative average deviation (RAD) obtained by the three equations were 1.48 × 10–4, 3.32% (enalapril hydride) and 2.82 × 10–4, 4.36% (enalapril maleate), respectively. It was found from the RMSD value that the modified Apelblat equation is more suitable to describe the solubility behavior of enalapril hydride and enalapril maleate in these solvents.

Formulation and optimization of Enalapril Maleate-loaded floating microsphere using Box–Behnken design: in vitro study

“…The drug encapsulation efficiency and drug loading in Formulation-A were comparatively lower than Formulation-B. It might be because of the presence of ethanol, which increases the aqueous solubility of the EnM, while in Formulation-B, drug loading and encapsulation efficiency are higher because of the absence of alcohol-induced cosolvent effect and lower solubility of EnM in acetonitrile as compared to alcohol (Qiao et al, 2018). The percentage yield of Formulation-A and Formulation-B was 34.19% and 29.314%, respectively.…”

“…The greater cumulative drug release in Formulation-A was due to the use of the ethanol. As a solvent, ethanol might act as a cosolvent during the dissolution of the microsphere since the solubility of EnM is higher in alcohol compared to acetonitrile, consequently enhancing solubilization of EnM itself (Qiao et al, 2018). The in vitro drug release of Formulation-A was nonsignificantly higher than Formulation-B at 1 and 8 hours (p > 0.05).…”

“…However, the drug loading declined with the increment in the solvent ratio. With the increase in the solvent ratio, drug loading might have been decreased due to the alcohol-induced cosolvent effect (Qiao et al, 2018). Drug loading also decreased with the increase in stirring time.…”