Physical characteristics and aerosol performance of naringin dry powders for pulmonary delivery prepared by spray-drying.

The aim of the present work was to develop dry powders containing naringin for a direct administration to the lung to combat oxidative stress. Naringin microparticles were prepared by spray-drying the neat flavonoid (2-5% w/v) from different water/ethanol co-solvents. The spray-dried powders were characterised for morphology, density, particle size distribution, residual humidity, crystallinity, solubility, thermal behaviour and respirable fraction. The fine fraction of the powders was measured by single-stage glass impinger and Andersen cascade impactor, using the Turbospin device for the deposition tests, wherein the dose to be aerosolised was premetered in a gelatine capsule. By increasing the ethanol content, the feed liquid turned from a suspension into a solution: the spray of flavonoid suspensions led to powders with high crystallinity degree, low water solubility and high bulk density, while the spray of drug solutions led to more amorphous particles, with higher solubility, lower density and improved aerodynamic behaviour. The optimisation of the operative parameters produced enhanced aerosol performance of the flavonoid powders containing only the active compound.