Carriers in Drug Powder Delivery

Abstract

The performance of dry powder inhaler (DPI) systems depends on the design of the powder formulation, the dose-metering system, and the device used to disperse the powder as an aerosol. Multiple factors associated with drug and carrier particles are known to influence dry powder performance. Elucidation of a mechanistic understanding of particulate system properties and how these relate to powder performance and the disruption of inter-particulate forces that cause aggregation has not yet been achieved. However, the complexity of interactions within dry powder formulations has not restricted research in this area. Various strategies of overcoming inter-particulate forces have been devised, ranging from active inhaler designs to powder engineering approaches. The influence of the interactive carrier system’s physicochemical properties (i.e. size, shape, chemical properties, surface roughness, electrostatics, humidity, and ternary excipients) on the performance of carrier-based systems has been examined extensively in the literature. In addition, matrix carriers, which contain drug and functional excipients for promotion of powder performance, control of pharmacokinetics, stability, controlled release of active drug and enhanced control of drug targeting, have also been investigated. Both the interactive carrier and matrix carrier approaches are attempts to develop DPI systems that perform as device-independent formulations and/or provide patient-independent delivery (controlled carrier systems). It seems likely that the future of DPI systems will combine both of these strategies with future developments in device design (formulation independency).