[New systems for colonic drug targeting]

Colonic drug delivery systems are useful for the treatment of inflammatory bowel diseases (ulcerative colitis, Crohn's disease), some carcinomas, gastrointestinal infections and diseases that are sensitive to circadian rhythms, such as asthma, angina pectoris and arthritis, where an intention time delay in the absorption of the drug is required. The colon region is a site for the entry of peptides, proteins, nucleotides and vaccines into the systemic circulation due to local absence of digestive enzymes. Colonic drug targeting ensures direct treatment at the disease site and a possible reduction in the administered dose. A drug is not absorbed into the systemic circulation, so the associated systemic adverse effects are reduced. Colonic drug delivery systems are based on exploitation of characteristics that are unique to the gastrointestinal tract (GIT), such as pH gradient along the GIT, long transit time through the GIT, increased intraluminal pressure and a presence of bacterial microflora in these regions.