Preparation, properties and biological activity of beta-cyclodextrin inclusion complex of menadione.

The molar ratio of menadione (vitamin K3) to beta-cyclodextrin in the microcrystalline inclusion complex showed this to be 1:3 with a menadione content of approximately 4.1-4.3%. Complexes with higher vitamin content could not be prepared. Bound and free vitamin can be readily separated by sublimation in vacuum. The menadione is highly stable in complexed form; in dry state it is released only when cyclodextrin is destroyed by heating to about 300 degrees C. Complexed menadione does not react with amino acids. Solubility and dissolution rate are strongly increased. Treating hypovitaminotic chickens with equivalent doses of menadione or menadione-beta-cyclodextrin complex and monitoring blood clotting times, recalcification times and prothrombin times the complex proved to be at least as effective as--or even somewhat more potent than--free vitamin. 1.5-2.0 micrograms/animal/d free or complexed menadione was sufficient to cover the daily vitamin K needs of chickens.