Physico-chemical considerations in the microencapsulation of a drug susceptible to hydrolysis.

摘要

Controlled release homogeneous matrix microspheres containing acetylsalicylic acid (ASA) were prepared by a simple mechanical process using Eudragit;ASA-loaded microspheres were analyzed at predetermined time points following immersion of the microspheres in temperature controlled (30;NMR evaluation of the C5 and C10 acyl esters of salicylic acid, as well as ASA, indicated that alteration of the microenvironment of the incorporated solutes had occurred. The matrix incorporated ASA is essentially shielded from hydrolytic attack until it is liberated into the external aqueous environment. Electrostatic association of ASA with the charged quaternary residues in the polymer along with the limiting availability of water within the microsphere may be responsible for the observed stability of ASA in aqueous swollen ASA-loaded Eudragit