Three-Dimensional Printing of Colon-Targeting Drug Delivery Systems (CTDDS)

In recent decades targeted drug delivery has obtained a significant interest for its ability to enhance therapeutic efficacy and reduce side effects of the drugs. Among them, colon-targeting drug delivery systems have been extensively investigated for treating inflammatory bowel diseases and colon cancer and delivering therapeutic proteins and peptides for systemic absorption. The current CTDDS are based on pH-dependent and/or timedelayed dependent release to deliver drugs to the colon without absorption from the upper Gastrointestinal Tract (GIT). Although the pharmaceutical industry has achieved a significant advancement in developing effective CTDDS, it still depends on one-size-fits-all. Consequently, the drug release by this approach will be highly influenced by the unstable GIT pH and intestinal transient time that patients with inflammatory bowel disease frequently experience which may result in premature or delayed colonic delivery of the drugs. 3D printing is a new technology that can easily build up 3D objects based on computer-aided design, consequently, it can fabricate personalized or on-demand dosage forms. Using different 3D printing techniques, printing materials and software designs of the dosage form, 3D printing can exert a high degree of control over the dose and release profile of the drug. This review highlights the most recent applications of 3D printing in the development of the CTDDS focusing on the type of the 3D printing technology, design and pharmaceutical polymers and the drug release profiles.