Co-amorphous system of Bifonazole for improved in-vitro permeation and antifungal activity

Bifonazole (BF), belonging to the newer class of antifungal drugs, is being widely explored for topical administration for fungal infections. It has proven to have better efficiency than other older drugs. However, it's low solubility poses a challenge in the formulation and, therefore, in the drug product's efficacy. Intending to harness the benefits of the drug, the objective of the current study was to prepare a supersaturated system of the drug with a coformer. A co-amorphous system (CAS) of BF and citric acid (CA) was prepared using solvent evaporation to achieve better permeation and antimicrobial efficacy after topical application. The prepared system was evaluated for its solid-state properties by DSC, XRD, and FTIR. The theoretical values of the glass transition temperature, as calculated by the Gordon-Taylor equation, correlated well with the observations of the thermal analysis. The prepared system was dispersed in propylene glycol to perform in-vitro permeation studies wherein enhanced permeation properties were noted. The CAS showed better antifungal properties against A. niger owing to better release and solubility of the drug. Thus, It was concluded that a co-amorphous system of BF is a promising formulation strategy for topical drug delivery.