Quercetin Solid Lipid Microparticles: a flavonoid for inhalation lung delivery

The aim of the present work was to develop solid lipid micro particles (SLMs), as dry powders containing quercetin for a direct administration to the lung for asthma therapy. Quercetin microparticles were prepared by o/w emulsification via a phase inversion technique, using tristearin as lipid and phosphatidylcholine as emulsifier. The quercetin SLMs were characterised for morphology, particle size distribution, residual humidity, crystallinity, thermal behaviour and in vitro respirable fraction. Furthermore, the toxicity and the in vitro transport of the SLMs on the air liquid interface model of the Calu-3 cell line was also investigated using a modified Twin –stage impinger apparatus. Results have showed that querectine SLMs can be formulated as dry powder suitable for inhalation drug delivery. These SLMs have been proven to be not toxic at the concentrations investigated and transported with a liner kinetic through the Calu-3 monolayer, possibly via a diffusion mechanism enhanced by the presence of the lipid/emulsifying excipients. Further studies are necessary to elucidate the exact mechanisms.