Research indicates that azoles, when combined with osteoporosis drugs known as bisphosphonates, are more effective at treating fungal infections. This combination has shown success in laboratory tests against dermatophytes, with promising implications for preventing resistance and enhancing drug efficacy.
Combining azoles with bisphosphonates enhances the treatment of fungal infections, showing significant efficacy in lab tests and potential in reducing drug resistance.
- Dermatophytes are fungi that cause skin, hair, and nail fungal infections.
- These infections often develop resistance to azoles, a common anti-fungal treatment.
- A new study suggests that adding common bone loss drugs to azoles can improve efficacy.
- In lab tests, combinations of these drugs worked against dermatophyte species and prevented resistance.
Introduction to Fungal Infections and Current Treatments
Human skin, hair, and nails are all vulnerable to fungal infections. While these infections are usually not serious, they’re difficult to fully resolve and often recur after treatment—sometimes for years. They’re also often resistant to treatments, including a common class of antifungals called azoles.
Enhancing Antifungal Efficacy With Bisphosphonates
A study published this week in mSphere points to a new way to boost the efficacy of azoles in treating those infections—combining them with commonly available drugs called bisphosphonates, usually used to treat osteoporosis. Previous work by the same research group has shown that adding bisphosphonates to azoles can effectively treat yeast infections from Candida and Cryptococcus species. The new study extends that finding to dermatophytes, which cause superficial infections.
The study suggests that bisphosphonates could be repurposed to use with azole antifungals, which are relatively nontoxic, and that the combination could be readily tested in clinical studies.
The Promise of Dual Drug Therapy
“There aren’t many good antifungal drugs around, and the fungus will always develop resistance no matter how you treat them,” said senior author Dee Carter, a mycologist at the University of New South Wales, Australia. “For what we’re proposing, to use 2 drugs at the same time, that resistance is much less likely.”
Carter says she was only a little surprised to see the synergistic effect in dermatophytes. This research project began years ago, she says, when her group conducted a series of genomic analyses on the response of pathogenic yeasts to drug treatment. That study led them to a genetic pathway that is “upstream” of the pathway targeted by azoles, and is instead targeted by bisphosphonates. “That’s often a good way to get drugs to work, is to target processes that are interlinked like that,” Carter said.
Laboratory Results and Future Research Directions
In the lab, Carter and her team tested 3 commonly available bisphosphonates (risedronate, alendronate, and zoledronate) in combination with 3 commonly available azole antifungals (fluconazole, itraconazole and ketoconazole). They tested these against clinical isolates from a diverse range of dermatophyte species that cause superficial infections. The combination of zoledronate and ketoconazole proved particularly effective against 8 of the 9 tested species. It also prevented the development of resistance.
Aidan Kane, mycologist, lead author of the study and a Ph.D. student in Carter’s lab, used fluorescence microscopy and other methods to show that the drug combination worked by weakening the cell membrane enough that the fungus could not survive. Beyond the dermatophytes, the group also found that bisphosphonate-azole combinations could act against molds that cause invasive disease, suggesting another possible clinical application for the drugs.
“You can use these combinations directly for superficial infections, like Candida or dermatophyte infections, and we’re hoping that with modified forms of the drugs we can create something that will also work systematically,” Carter said. “The next step is to continue testing bisphosphonate-azole combinations in animal models, and then test it in clinical trials.”
Reference: 5 June 2024, mSphere.
DOI: 10.1128/msphere00248-24
