A comparative study of PLGA microparticle properties loaded with micronized, nanosized or dissolved drug

The objective of this study was to compare properties of poly(lactide-co-glycolide) (PLGA) microparticles loaded with dexamethasone or hydrocortisone in the micronized, nanosized or dissolved state. Dexamethasone and hydrocortisone were nanosized by wet bead milling. The microparticles were prepared by a solvent extraction/ evaporation method and were characterized by particle size, encapsulation efficiency, drug solid-state, morphology, in vitro release and dynamic microparticle diameter changes during release. The micronized and nanosized drugs were still in crystalline form after encapsulation into PLGA microparticles with encapsulation efficiencies greater than 85 %. Encapsulating dissolved drugs resulted in lower encapsulation efficiencies (32 to 63 %) and the dissolved drug recrystallized within the PLGA matrix at a higher actual drug loading of 30 %. The order in drug release depended on the physical state of the encapsulated drug and was in the order of dissolved > nanosized > micronized drug. Interestingly, quasi-linear release profiles were obtained with 10 % nanosized dexamethasone in PLGA 502H and 503H microparticles. In conclusion, encapsulating dispersed and, in partic-ular, nanosized drug into PLGA microparticles is a promising tool to increase the encapsulation efficiency, to maintain a stable drug solid-state and to achieve a more continuous release profile.

Automated summary

This study compared the properties of PLGA microparticles loaded with dexamethasone or hydrocortisone in different physical states. The results showed that encapsulating nanosized or dissolved drugs into PLGA microparticles can increase encapsulation efficiency, maintain stable drug solid-state, and achieve a more continuous drug release profile.