Nanostructured mucoadhesive microparticles for enhanced preocular retention.

We describe nanostructured microparticles (NMs) containing a mucoadhesive polymer for enhanced preocular retention and consider them as potential carriers of drugs to the eye. These NMs are each composed of entangled nanofibers to give an enlarged specific surface area, and thus can better adhere to the preocular mucus surface. This physical design allows the microparticles still to be composed mainly of a wall material, poly(lactic-co-glycolic acid), as required for controlled drug delivery, while the effects of an additive, mucoadhesive material, polyethylene glycol, can be synergistically improved via the nanostructured morphology. Thus, when formulated in a dry tablet dosage form, the NMs in this work show more than a 10-fold increase in preocular retention in vivo compared to conventional spherical microparticles. Therefore, we conclude that these mucoadhesive NMs can reside on the preocular surface for a prolonged period, and thus appear to be a promising system for topical drug delivery to the eye.