Formulation Strategy for the Delivery of Cyclosporine A: Comparison of Two Polymeric Nanospheres

A wide range of nanoparticles has been explored for the delivery of highly hydrophobic drugs, but very few publications provide comparative data of the performance of different nanoparticles. To address this need, this publication compares poly(lactic-co-glycolic acid) (PLGA) nanoparticles and nanospheres made from tyrosine-derived tri-block copolymers (termed TyroSpheres) for their respective performance as carriers for cyclosporine A (CSA). Using previously reported data on PLGA, we followed similar experimental protocols to evaluate the in vitro characteristics of TyroSpheres. Although there are some similarities between the two particle systems for the delivery of CSA, such as effective encapsulation and epidermal skin penetration, several differences were notable. First, the methods of preparation were different, i.e., self-assembly and emulsion-diffusion-evaporation process for TyroSpheres and PLGA, respectively. Second, TyroSpheres provided 7-day diffusion-controlled release, whereas PLGA nanoparticles provided >21-day erosion-controlled release. Third, the size of TyroSpheres was measured to be ~60-70 nm irrespective of drug loading, whereas the size of PLGA nanoparticles (~100-250 nm) was dependent on drug loading and the method of preparation. Overall, this publication provides a direct comparison between two different types of nanoparticles and illuminates the respective advantages and disadvantages, using CSA as a model for the release of highly hydrophobic drugs.