Development of inhalable dry gene powders for pulmonary drug delivery by spray-freeze-drying

Abstract

There is considerable potential for pulmonary gene therapy as a treatment for a number of conditions for which current treatment is inadequate. Delivering genes directly to the lungs by dry powder inhalers (DPIs) have attracted much attention due to better stability of genes. Formulating genes as powders for aerosol delivery is a challenge as it requires not only flowability and dispersibility of the powders but also maintaining gene stability and biological activity during manufacturing and delivery. In this review, we aim to provide an overview about the potentials of spray-freeze-drying (SFD) for the development of inhalable dry gene powders for pulmonary drug delivery. We will discuss the main steps involved within the production process (i.e., spraying, freezing and drying) and introduce different SFD methods which can successfully be used for the production of porous particles whose physical and aerosol characteristics are considered to be ideal for use in pulmonary drug delivery.