Effect of mucin extraction method on some properties of metronidazole mucoadhesive loaded patches

Abstract

To evaluate the effects of mucin extraction method and plasticizer concentration on the bioadhesive strength and metronidazole release profile from mucin-based mucoadhesive patches. Mucin was extracted from the giant African snail Archachatina marginata by differential precipitation with acetone and alum. Various batches of metronidazole loaded mucoadhesive film patches were prepared with the precipitated mucin and varying volumes (0.2, 0.5, and 1 ml) of polyethylene glycol (PEG) as plasticizer. Properties evaluated include: thermal properties (DSC), weight uniformity, patch thickness, folding endurance, moisture content and uptake, bioadhesion, drug content and in vitro and ex vivo diffusion studies. DSC analysis showed no interaction between metronidazole and mucin irrespective of the means of extraction. Extraction of mucin with acetone and alum gave a percentage yield of 0.1 and 0.08 %w/w, respectively. Patch weight range from 0.17 - 0.28 g, moisture content (17 %) and moisture uptake was highest with patches prepared with acetone-precipitated mucin (up to 117 %) and decreased as PEG concentration was increased. All the patches showed bioadhesion values between 0.90 - 1.97 g/sec. Drug diffusion across rat fundus was highest at 74 % after 12 h from patches prepared from alum precipitated mucin containing least amounts of PEG. The potential for alternative extraction method of mucin (with alum) can be improved as suitable substitute for the expensive acetone extraction method. Keywords : Bioadhesion; Drug diffusion; Mucin; Acetone-precipitate; Alum-precipitate