Sugar-Branched-Cyclodextrins as Injectable Drug Carriers in Mice

Abstract

The purpose of this study was to investigate stable complexation of drug in blood by sugar-branched-β-cyclodextrins (β-CDs) such as glucose (glu)–or galactose (gal)–branched-β-CDs and the pharmacokinetic disposition of drug in sugar-branched-β-CD complex. Complexation of steroidal drugs in sugar-branched-β-CDs and their replacement by cholesterol were measured. The complexes of dexamethasone/glucosyl-β-CDs (dexamethasone/glu-β-CD or dexamethasone/glu-glu-β-CD) were not replaced by cholesterol, which is a representative endogenous compound, whereas the complex of dexamethasone7/β-CD was replaced by cholesterol. The same results were obtained in steroidal drugs such as hydrocortisone, triamcinolone, and prednisolone. Thus, the use of glu-β-CD and glu-glu-β-CD permitted the stable complexation of the drug in water. Stability constants of dexamethasone/glu-glu-β-CD and dexamethasone/gal-glu-β-CD complexes are the same, which means that the sugar moiety of the side chain in β-CD has little effect on stability constants. After the dexamethasone/gal-glu-β-CD complex or the dexamethasone/glu-glu-β-CD complex (dexamethasone: 1 mg/body) was administered intravenously to mice, dexamethasone concentrations in liver tissue and blood were measured. The dexamethasone/gal-glu-/-CD complex (66.1±1.7 μg as dexamethasone/gram of liver tissue) was distributed to liver tissue significantly more than the dexamethasone/glu-glu-β-CD (β-CD) complex (59.9 ± 1.0 μg as dexamethasone/gram of liver) at 30 min after administration (p <. 05). Sugar-branched-β-CD gave a water-soluble and stable complex for dexamethasone and changed the disposition of dexamethasone. Sugar-branched-β-CDs are potentially excellent carriers for a steroidal injectable formulation.