[Characteristics of a new controlled release formulation of ursodesoxycholic acid]. / Aspetti relativi alle caratteristiche di una nuova formulazione di acido ursodesossicolico a rilascio controllato.

Ursodeoxycholic acid, like all weak acids, has to be formulated so as his release and absorption depend as little as possible by the pH of gastrointestinal tract. To obtain this result a controlled release formulation of UDCA was developed, based on bioadhesive technique. This allowed a longer residence and absorption time of the active ingredient both at gastric (due to gastrosoluble rate) and duodenal-jejunum level (gastroresistant rate). Thus, all the absorption windows for bile acids are utilized, to ameliorate the total bioavailability of the drug.

[A new inclusion complex of silibinin and beta-cyclodextrins: in vitro dissolution kinetics and in vivo absorption in comparison with traditional formulations]. / Nuovo complesso di inclusione tra la silibina e la beta-ciclodestrina: velocità di dissoluzione in vitro e assorbimento in vivo in confronto a formulazioni tradizionali.

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.