Implantable powder-carrying microneedles for transdermal delivery of high-dose insulin with enhanced activity.

Recently, numerous transdermal drug delivery systems have been developed for safe and efficient delivery of biopharmaceuticals. Dissolving microneedles (DMNs) are one such drug delivery system, which have been developed to treat a variety of diseases in a minimally invasive manner. However, current DMN fabrication methods involve a reconstitution process of the therapeutics, which can result in degradation of the therapeutics or limited loading capacity for a reasonable application size. In the present study, we developed self-administrative powder-carrying microneedles (PCMs), lacking a reconstitution step, which implant insulin powder directly inside the skin without using a sticky patch. Compared with DMNs in the same geometries, the PCMs delivered the required dose in a more condensed form without considering insulin solubility and degradation during the fabrication process. Moreover, PCMs showed enhanced long-term stability and prolonged release kinetics, which could be utilized to treat diabetes without apparent safety issues. This implantable PCM technique will greatly impact the future of transdermal drug delivery systems because it is applicable to any type of therapeutic available in a dry powder formulation for a wide variety of biomedical applications.