New Carriers for Bioadhesive Gastroretentive Drug Delivery Systems Based on Eudragit® EPO/Eudragit® L100 Interpolyelectrolyte Complexes

Abstract

The aim of this study was the analysis of interpolyelectrolyte complexes (IPECs) based on Eudragit® EPO and Eudragit® L100 as prospective carriers for gastroretentive drug delivery systems (GRDDS) using two model drugs: metronidazole (MZ) and acyclovir (ACR). Eudragit® EPO/L100 IPECs with different pH concentrations were characterized by different degrees of swelling in mimicking fasted stomach medium (0.1 M HCl) and saved their shape for 6 h. The microenvironmental changes in IPEC structures in acidic medium were investigated using FT-IR spectroscopy, thermal and elemental analysis. IPEC samples showed bioadhesive properties that were not significantly different from the positive control (Carbopol) in the test with the mucin compacts. The release rate of metronidazole (class I BCS) from IPEC matrices increased with the increasing degree of swelling. IPEC 1 provided 49.62 ± 6.20% and IPEC 2 reached 87.69 ± 5.15% of metronidazole release after 6 h in mimicking fasted stomach medium (0.1 M HCl). The total amount of released acyclovir (class III BCS) from IPEC 1 was 25.76 ± 5.67% and from IPEC 2 was 21.48 ± 5.00%. Release of both drugs was controlled by relaxation of polymeric chains in matrices according to the Peppas–Sahlin model. According to the received results, investigated interpolymer complexes are prospects for further evaluation as carriers for gastroretentive bioadhesive systems.