3D printing for enhanced drug delivery: current state-of-the-art and challenges.

Three-dimensional (3D) printing has recently appeared as one of the most promising additive manufacturing techniques to fabricate 3D objects, with uses spanning from engineering prototyping to medicines and cell-laden models for biomedical applications. Regardless of the type and underlying theory, 3D printing techniques involve the deposition of materials such as thermoplastic polymers or hydrogel in sequential layers one onto another to produce a 3D object. 3D printing has recently gained momentum in developing various drug delivery systems for pharmaceutical applications which is reflected by the exponential rise in the number of published papers and patents in recent years. Whilst the future of 3D printing techniques is bright, various obstacles need to be overcome before it can be applied practically in commercial-scale production. This review article discusses current approaches of altering drug delivery when manufacturing 3D printed dosage forms that vary in their drug release profiles and characteristics. Such achievements correspond to developing and delivering patient-specific treatments. With each type of 3D printing application, there are great benefits, and these are highlighted, however, a critical discussion will underline the limitations and challenges associated with 3D printing.