Purpose: The aim of the present work was to develop solid lipid micro particles (SLMs), as dry powders containing quercetin for direct administration to the lung.
Methods: Quercetin microparticles were prepared by o/w emulsification via a phase inversion technique, using tristearin as the lipid component and phosphatidylcholine as an emulsifier. The quercetin SLMs were characterised for morphology, drug loading (15.5 % ± 0.6, which corresponded to an encapsulation efficiency of 71.4%.), particle size distribution, response to humidity, crystallinity, thermal behaviour and in vitro respirable fraction. Furthermore, the toxicity and the in vitro transport of the SLMs on an air liquid interface model of the Calu-3 cell line were also investigated using a modified twin-stage impinger apparatus.
Results: Results showed that quercetin SLMs could be formulated as dry powder suitable for inhalation drug delivery (20.5 ± 3.3% fine particle fraction ≤ 4.46 mm) that was adsorbed, via a linear kinetic model across the Calu-3 monolayer (22.32 ± 1.51 % over 4 hours). In addition, quercetin SLMs were shown to be non-toxic at the concentrations investigated. Interestingly, no apical to basolateral transport of the micronized quercetin was observed over the period of study.
Conclusions: These observations suggest quercetin diffusion was enhanced by the presence of the lipid/emulsifying excipients in the SLMs; however further studies are necessary to elucidate the exact mechanisms.