Design and development of liposomes for colon targeted drug delivery.

Background: Local delivery to bowel tissue through oral administration is a challenging but a desirable goal to treat diseases like inflammatory bowel disease (IBD). Colon specific drug delivery system should be capable of protecting the drug en route colon.

Purpose: Liposomes have shown potential to specific accumulation at inflammation site thus reduce toxicity; hence it can be used for effective treatment of IBD.

Methods: Liposomes prepared using thin film hydration method. Statistical design was used for optimization. Colitis was induced using acetic acid. Inverted sac method was used as ex vivo model for IBD. Myeloperoxidase (MPO) activity and histopathology comparative study was carried out. Liposomes were formulated in enteric coated capsules to deliver the liposome specifically in initial segment of colon.

Results: Particle size and entrapment efficiency were between 200 and 300 nm and 40 and 60%, respectively. In vivo and ex vivo study indicates higher accumulation of liposomes in colonic region as compared to pure drug. Enteric coated capsules delivered the drug after 5 h lag time.

Discussion: Low particle size is attributed to low lipid content and stabilization due to surfactant. At higher cholesterol level, vesicles cannot reshuffle into smaller vesicles due to rigidization. Study shows higher accumulation of liposomes due to its lipoidal nature as compared to pure drug due to membrane transfer mechanism of drug thus MPO significantly lowers as compared to standard group (p < 0.05).

Conclusions: Higher accumulation of liposomal drug in inflammatory area and specific release of liposomes by enteric coated capsules provide better option for the treatment of colonic disease.