Effect of drug physicochemical properties on in vitro characteristics of amphiphilic cyclodextrin nanospheres and nanocapsules

Nanospheres and nanocapsules of an amphiphilic beta-cyclodextrin, beta-CDC6, were evaluated using a group of steroid drugs to determine the effect of drug physicochemical properties (e.g. partition coefficient, drug:CD association constant k(1:1), aqueous solubility) on loading and release profiles of the nanoparticles. Model drugs used were hydrocortisone, testosterone and progesterone. Inclusion complexes were formed between model drugs and beta-CDC6 by the co-lyophilization technique and were characterized by DSC analysis and FTIR spectroscopy. Nanospheres and nanocapsules were prepared directly from these inclusion complexes and alternatively by the conventional preparation technique. It was observed that loading depended highly on the technique used. For nanospheres, drug characteristics played a significant role while for nanocapsules this factor had no significant effect on loading values. Release of drugs from nanospheres was completed in 2h, regardless of drug physicochemical properties with high-loading technique. On the other hand, drug release from nanocapsules was largely dependent on drug properties. Only 30% of progesterone was released in 24h, while hydrocortisone was completely released in 8h. Thus, drug properties are significant for the formulation of nanocapsules and nanospheres. Desired loading and release properties could be achieved by selecting the appropriate drug delivery system and the optimum drug.