Background: 18β- glycyrrhetinic acid (Gly) is the major bioactive component of licorice roots and rhizomes of the Glycyrrhiza glabra species. It shows many activities as antiviral, anti-inflammatory, antioxidant, antimicrobial, antifungal, however its use in health field is very limited due to the low water solubility. Methods: This paper deals with the development of a new technological approach for Gly dissolution rate enhancement. It consists in the intercalation of Gly in molecular form (guest) in the interlamellar spaces between the inorganic spaces (host) of the anionc clays “hydrotalcites” (HTlc) to obtain the hybrids MgAl-HTlc-Gly and ZnAl-HTlc-Gly. Gly can find applications both for systemic and local therapies, thus advantages in the use of the hybrids in these two fields was investigated.
Results: MgAl-HTlc-Gly and ZnAl-HTlc-Gly can be orally administered as dry powder (e.g. in hard capsules). In vitro release studies, performed in intestinal environment conditions, showed that Gly dissolution rate from hybrids is enhanced in comparison to the crystalline form. Because of the antiinflammatory and antifungal activities, Gly is an interesting molecule to be used for treatment of vulvovaginal Candidiasis. Thus, mucoadhesive vaginal emulgels containing the hybrids were developed and characterized. These formulations are advantageous as are able to prolong contact time between the formulation and the vaginal mucosa and to improve Gly dissolution rate, with consequent enhanced topical bioavailability.
Conclusions: The obtained results suggest that the purposed technology is able to enhance Gly dissolution, property maintained when the hybrids are formulated both as oral or topical products.