RESUMEN
The very low bioavailability of silybinin, the main constituent of silymarin, so far prevented the development of an oral pharmaceutical specialty based on this active ingredient. To overcome this difficulty, an inclusion complex between Silybinin and beta-Cyclodextrin was prepared. The new complex was compared in vitro tests (dissolution rate) and in a in vivo test (rat bile elimination) with silybinin, silymarin and one traditional formulation based on silybinin. The results show a dramatic increase in the dissolution rate of the complex (> 90% within 5 min) respect to the silybinin that confirm to be practically insoluble (< 5%). The in vivo results agree with the dissolution rates; after administration of the silybinin complex p.o., the silybinin concentration in the rat bile was near 20 times more than after administration of silybinin as is or in a traditional formulation. In the last two cases, the silybinin concentration was even 6 times less than after administration of the same amount of silymarin. These data show that the beta-CD complex solved the problem of the bioavailability of silybinin which, in the traditional formulation utilised as reference, proved to be not bioavailable.