Objective: The present study was carried out to design an efficient formulation to target the drug loaded liposomes exclusively to the inflamed colonic region by protecting the payload from releasing in the upper gastro intestinal tract (GIT) by using two polymers. Methods: Liposomes were prepared by lipid film hydration method followed by chitosan coating and finally encapsulation with eudragit S-100. The coated as well as uncoated liposomes were characterized for entrapment efficiency, size and surface charge. In vitro drug release study was carried out using three step pH gradient method. Acetic acid was used to induce colitis. Ex vivo tissue drug entrapment study was done using excised tissues of male albino rats. In vivo efficiency study was done by comparatively studying the histopathology and myeloperoxidase (MPO) activity. Results: Formulations showed entrapment efficiency (93-91%) and size (99-290nm). Formulation showed Tlag of 6 hrs and by the end of 16th h, 82% drug release was achieved. Ex vivo studies revealed higher tissue-drug entrapment (22.58±2.52%) in inflamed colon when compared to healthy colon (22.58±2.52%). Histopathological studies showed marked reduction in inflammation in case of ECLs (eudragit encapsulated chitosan coated liposomes) treated groups than standard drug treated rats. The reduction in healing was further confirmed by the MPO assay which showed significant reduction in MPO (900.25±1.31 ng/ml) levels of ECL treated groups than standard drug treated (1990.32±2.11 ng/ml) and IBD group (2125.54±1.56 ng/ml). Conclusion: The ECLs showed site specific release of liposomes and increased accumulation of liposome entrapped drug in the inflamed colon.
Key words: Acetic acid induced rat colitis, Colon targeting, Ex vivo tissue entrapment, Histopathological studies, IBD, MPO activity.