Antifungal Activity and Synergistic Interaction Assessment of Allicin Harmine Transdermal Patches Using Fractional Inhibitory Concentration Index (FICI)

Abstract

Fungal infections represent a significant therapeutic challenge due to increasing resistance to conventional antifungal agents and limited efficacy of existing topical formulations. The present study was designed to evaluate the antifungal activity and synergistic interaction of Allicin–Harmine-loaded transdermal patches using the Fractional Inhibitory Concentration Index (FICI). The transdermal patches were formulated to enhance skin permeation, sustain drug release, and improve the therapeutic effectiveness of both phytoconstituents. The antifungal potential of the developed formulation was assessed against selected fungal strains using standard microbiological methods, and the activity was compared with individual drug components. Synergistic interactions between Allicin and Harmine were quantified using the FICI model to determine the nature of interaction, whether synergistic, additive, indifferent, or antagonistic. The results demonstrated that the combination of Allicin and Harmine in transdermal patch form exhibited enhanced antifungal activity compared to their individual effects. The calculated FICI values indicated a synergistic interaction between the two bioactive compounds, suggesting improved antifungal efficacy when used in combination. This enhanced activity may be attributed to the complementary mechanisms of action of Allicin and Harmine, along with improved skin permeation and sustained drug release provided by the transdermal delivery system. The study confirms that transdermal delivery of Allicin and Harmine can effectively enhance antifungal performance and offers a promising alternative strategy for overcoming resistance associated with conventional antifungal therapy. Overall, the developed formulation demonstrates significant potential for further preclinical and clinical evaluation as an effective antifungal therapeutic system.