Graphene oxide as a functional excipient in buccal films for delivery of clotrimazole: effect of molecular interactions on drug release and antifungal activity in vitro

Graphene oxide (GO) is an amphiphilic, high surface area material with great potential as a functional excipient in drug delivery. The present study aimed at incorporating GO in buccal polyelectrolyte films for delivery of antifungal drugs and investigating the effect of GO on the film properties and drug release profiles, as well as antifungal activities. Mucoadhesive excipients chitosan and alginate were selected to form polyelectrolyte films with the antifungal drug clotrimazole. The buccal formulations were prepared by mixing the excipients and clotrimazole via probe sonication, followed by film casting and drying. Inclusion of GO in the formulations increased clotrimazole release from the films in vitro (pH 6.8), possibly due to GO altering the electrostatic interactions between chitosan and alginate. An increase of in vitro activity against Candida albicans was observed when 0.04 wt% GO was added in the formulation containing clotrimazole. However, when the GO amount increased to 0.09 wt%, the films had similar antifungal ability to the films with 0.04 wt% GO, suggesting that the electrostatic and hydrophobic interactions between GO and clotrimazole also affects the antifungal effect of clotrimazole. In summary, GO has a great potential as a functional excipient for delivery of antifungal drugs.