Polysaccharides: Is There An Opportunity For Application As Lung Delivery Excipients?
Ana Grenha
Centre for Marine Sciences, Faculty of Sciences and Technology, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
Research Institute for Medicines (iMed.ULisboa), Faculdade de Farmácia da Universidade de 7 Lisboa, Av. Prof. Gama Pinto, 1649-003, Lisboa, Portugal
Summary
Dry powders and dry powder inhalers (DPI) are currently of the most used and investigated inhalable formulations and devices, respectively. The higher stability characteristic of solids, the lower environmental impact of DPIs, and the higher flexibility of dry powder formulations contribute to their popularity. Dry powder formulations typically involve the use of new excipients, which assume different roles that include the improvement of aerosolization properties or of formulation stability, the enhancement of targeting abilities, among others. Excipients approved for inhalation comprise a limited list. This prevents progresses in the area, as the current need for more targeted and effective therapies, implies the development of new technologies and sophisticated medicines, typically involving new excipients. From the range of excipients proposed by the literature, polysaccharides are of the most popular, not only because of their structural flexibility and low cost, but also due to the identification of functional abilities, such as targeting capacity. Our research group has proposed the use of polysaccharides in several lung delivery approaches. Some polysaccharides were used to actively target macrophages, owing to a chemical composition that favours the interaction with the cell surface receptors. In this lecture, results of the application of polysaccharides (locust bean gum and konjac glucomannan) as excipients of inhalable dry powders will be showcased, particularly exploring cell targeting abilities, exemplified by an application in inhalable tuberculosis therapy. The concerns regarding excipient safety for inhalation applications will be addressed and preliminary toxicological results subsequent to in vivo exposure presented.
Key Message
Polysaccharides have important features that may improve the performance of inhalable therapies, but toxicological concerns need to be carefully addressed before their approval.