The delivery of an orally inhaled API to the deep lung can be performed using different drug-delivery platforms, such as nebulizers, pressurized metered dose inhalers (pMDI), and dry powder inhalers (DPI). DPIs are increasingly becoming a more important drug delivery option and are expected to hit double-digit figures, reaching global sales of $31.5 billion in 2018

DPIs are conventionally formulated using a carrier-based approach, in which the API is size-reduced until it reaches an inhalable particle size and is further blended with a lactose carrier to enable dose metering and to improve powder flowability and dispersibility. Even though this formulation approach is the most commonly used, it presents several drawbacks. To overcome the limitations, as well as to address the renewed interest in pulmonary delivery of biotherapeutics and other advanced therapies, several alternative particle engineering approaches have been devised over the years, such as the production of composite particles by spray-drying where the API is embedded in an excipient matrix.

Although the development of a DPI seems straightforward, it is a complex area that integrates multiple fields of knowledge. In a general way, the success of a DPI produced using a carrier-based formulation approach will be determined by the API physicochemical properties, the formulation composition and process, the device and operating conditions, the patient–device relationship, the environmental variables, and ultimately, patient compliance. In this article, Gonçalo Andrade, business development manager at Hovione, spoke to Pharmaceutical Technology about the key considerations when developing an orally inhaled dry-powder inhalation formulation.