Pharmacokinetics and enhanced oral bioavailability in beagle dogs of cyclosporine A encapsulated in glyceryl monooleate/poloxamer 407 cubic nanoparticles

Efforts to improve the oral bioavailability of cyclosporine A (CyA) remains a challenge in the field of drug delivery. In this study, glyceryl monooleate (GMO)/poloxamer 407 cubic nanoparticles were evaluated as potential vehicles to improve the oral bioavailability of CyA. Cubic nanoparticles were prepared via the fragmentation of a bulk GMO/poloxamer 407 cubic phase gel by sonication and homogenization. The cubic inner structure formed was verified using Cryo-TEM. The mean diameters of the nanoparticles were about 180 nm, and the entrapment efficiency of these particles for CyA was over 85%. The in vitro release of CyA from these nanoparticles was less than 5% at 12 h. The results of a pharmacokinetic study in beagle dogs showed improved absorption of CyA from cubic nanoparticles as compared to microemulsion-based Neoral((R)); higher C(max) (1371.18 +/- 37.34 vs 969.68 +/- 176.3 ng mL(-1)), higher AUC(0-t) (7757.21 +/- 1093.64 vs 4739.52 +/- 806.30 ng h mL(-1)) and AUC(0-infinity) (9004.77 +/- 1090.38 vs 5462.31 +/- 930.76 ng h mL(-1)). The relative oral bioavailability of CyA cubic nanoparticles calculated on the basis of AUC(0-infinity) was about 178% as compared to Neoral((R)). The enhanced bioavailability of CyA is likely due to facilitated absorption by cubic nanoparticles rather than improved release.