Preparation, characterization and pharmacokinetic studies of tacrolimus-dimethyl-β-cyclodextrin inclusion complex-loaded albumin nanoparticles.

The purpose of the study is to develop a new formulation for clinically used anti-cancer agent tacrolimus (FK506) to minimize the severe side effects. Toward this end, a new formulation method has been developed by complexation of FK506 with an hydrophilic cyclodextrin derivative, heptakis (2,6-di-O-methyl)-β-cyclodextrin (DM-β-CD) using ultrasonic means. The resulting complex displays dramatically enhanced solubility of FK506. Then bovine serum albumin (BSA) nanoparticles were prepared directly from the preformed FK506/DM-β-CD inclusion complex by the desolvation-chemical crosslinking method, with the size of 148.4-262.9 nm. Stable colloidal dispersions of the nanoparticles were formed with zeta potentials of the range of -24.9 to -38.4 mV. The entrapment efficiency of FK506 was increased as high as 1.57-fold. Moreover, notably FK506 was released from the nanoparticles in a sustained manner. As demonstrated, pharmacokinetic studies reveal that, as compared with FK506-loaded BSA nanoparticles, the FK506/DM-β-CD inclusion complex-loaded BSA nanoparticles have significant increase at T(max), t(1/2), MRT and decrease at C(max). In summary, these results suggest that the drug/DM-β-CD inclusion complex-loaded BSA nanoparticles display significantly improved delivery efficiency for poorly soluble FK506 or its derivatives.