Gemcitabine anticancer activity enhancement by water soluble celecoxib/sulfobutyl ether-ß-cyclodextrin inclusion complex.

We investigated the complexation of celecoxib (CCB) into sulfobuthyl-ether-ß-cyclodextrin (SBE-ß-CD) for the realization of an inhalable dry-powder formulation containing gemcitabine (GEM) for lung anticancer therapy. Complexation increased the water solubility of CCB (0.003 mg/mL and 0.834 mg/mL for CCB free and complexed, respectively) and produced a quantitative dissolution of the drug within 15 min. The CCB/SBE-ß-CD inclusion complex showed a high stability constant (8131 M-1) not influenced by the presence of GEM in solution. Two-dimensional NMR experiments and computational studies demonstrated that the pyrazole ring of CCB penetrates deeper into SBE-ß-CD from the secondary rim. The aromatic rings are positioned at the edge of the cavity, establishing hydrogen bonds with the SBE-ß-CD that stabilized the complex. CCB showed limited cytotoxic activity on A549 cell lines. Complexation significantly increased activity passing from 30% to 45% cell mortality. Moreover, CCB/SBE-ß-CD strongly improved the cytotoxicity of GEM, observing about 60% of cell mortality for the combined formulation.

Physicochemical properties of inclusion complexes of highly soluble ß-cyclodextrins with highly hydrophobic testosterone propionate.

Hydroxypropyl-ß-cyclodextrin (HP-ß-CyD) and sulfobutyl ether-ß-cyclodextrin (SBE-ß-CyD) were used to generate hydrophilic complexes of the poorly water-soluble drug testosterone propionate (TP). The inclusion complexes were obtained by freeze-drying, and then analyzed at both liquid and solid states. Phase solubility studies, performed according to the type-AL solubility diagrams of TP in presence of both CyDs, suggested the formation of water-soluble complexes at 1:1 molar ratio. These results were confirmed by continuous variation method (Job's plot). Both CyDs increased water-solubility of TP 100-fold as compared to the native drug. The host-guest arrangement of CyD complexes in a water solution was further investigated by one- and two-dimensional NMR spectroscopy, highlighting the insertion of the tetracyclic ring of TP into the CyD cavity, and the interaction of the pending ester chain of drug with the primary hydroxyl groups of CyDs at the narrow end of the toroid structure. In solid phase, FTIR-ATR spectroscopy showed that the CO stretching mode of the TP vibrational spectrum changed if the complex between the drug and CyDs occurred. This change is temperature-dependent, and its evolution, accounted for by deconvolution procedures, provided the thermodynamic parameters explaining the mechanisms involved in the formation of inclusion complexes.