Glycyrrhizin gel as vehicle for idoxuridine topical preparation: skin permeation behaviour.

The in vitro skin permeation behaviour of idoxuridine (IDU) from a new preparation containing glycyrrhizin gel as carrier was tested and compared with that from a commercial IDU ointment (Virusan) at two temperatures on intact and stripped skin. At 34 degrees C the normalized flux (Fn) values were six times higher for the IDU glycyrrhizin gel than for Virusan when tested on intact hairless mouse skin. At 25 degrees C, Fn values were 22 and 25 times greater for the gel formulation using intact and stripped skin, respectively. These in vitro results, showing that IDU penetrates the skin more effectively when incorporated in the glycyrrhizin gel than in the ointment, correlate well with the previously reported efficacy of the gel tested in vivo.