Ceramic microneedles and hollow microneedles for transdermal drug delivery: Two decades of research

There are exciting developments in the research domain regarding the use of ceramic microneedles (CMs) and hollow microneedles (HMNs) for transdermal drug delivery. Several microfabrication techniques (micromolding, microreplication, photopolymerization, etching, modified LIGA, etc) have been used to make these microneedle devices. Over the last two decades, progress has been achieved regarding the development of porous ceramic microneedles into which medications can be incorporated at room temperature-a clinically useful process especially for thermolabile compounds. The fabrication process for hollow microneedles has also been optimized though the use of such techniques such as sacrificial micromolding and the modified LIGA process. This review sheds light on the fabrication of ceramic and hollow microneedles as well as the use of these devices for the transcutaneous transport of a wide range of drugs-from small molecules to proteins.