Fighting fungal disease

December 1, 2005

National report — From griseofulvin to terbinafine, oral medications to rid patients of fungal disease have evolved to treat a broader spectrum of disease, with fewer side effects. Topical medications have improved, as well, but still are not nearly as effective as oral prescriptions.

National report - From griseofulvin to terbinafine, oral medications to rid patients of fungal disease have evolved to treat a broader spectrum of disease, with fewer side effects. Topical medications have improved, as well, but still are not nearly as effective as oral prescriptions.

Better understanding

Researchers have discovered during the last decade that the tendency to get dermatophyte fungus in the toenails and possibly elsewhere (although it has not been proven elsewhere) is inherited in an autosomal, dominant fashion, with incomplete or variable penetrance, according to C. Ralph Daniel, M.D., dermatologist, clinical professor of dermatology at the University of Mississippi Medical Center, Jackson, Miss.

Recurrent dermatophyte, or ring worm, usually starts on the feet, which act as a reservoir for the fungus, Dr. Daniel tells Dermatology Times. Patients break the seal between the nail plate and the nailbed. The fungus comes off the foot, gets into the nail and the nails, and the feet act as a reservoir for the fungus to move elsewhere on the body.

It is more common for younger adults and older people to get fungus in the nails, feet and groin areas, whereas the most common age for fungus in the scalp is before puberty. Tinea capitis is common and very contagious, Dr. Daniel says.

The best way to diagnose fungal diseases of the skin and scalp is by KOH preparation and fungus culture. Dr. Daniel says that using one or both of these diagnostic tests is important before beginning treatment.

Oral options

Griseofulvin, a pill and the only Food and Drug Administration-approved pediatric medicine, was among the first oral dermatophyte treatments, according to Dr. Daniel.

Broad spectrum antifungals followed. Ketoconazole covers a dermatophyte fungus like griseofulvin, but offers the additional benefit of treating yeast, tinea versicolor and some of the common deep fungus infections within the body.

"Today, dermatologists do not often use ketoconazole because we know about one out of 10,000 to 15,000 may get a chemical hepatitis from it, and the medication interacts with a lot of different medications," Dr. Daniel says.

Two other oral antifungals came out later: itraconazole and terbinafine.

Itraconazole is a second generation oral azole and has a similar spectrum of activity as ketoconazole for yeast, dermatophytes, tinea versicolor and internal fungi. The problem is that, like ketoconazole, it interacts with many medications, and dermatologists should not prescribe it to CHF patients, Dr. Daniel says.

Terbinafine is specific for dermatophyte infections and has some activity against yeast and other fungi, but has only been approved for dermatophytes of toenails, Dr. Daniel says.

Dermatologists often use fluconazole, which is approved to treat yeast infection, off label to treat dermatophytes on the body, scalp and nails, he adds.

Topical treatments

Topical, over-the-counter treatments for dermatophytes include topical terbinafine. In practice, Dr. Daniel finds the topical treatments do little for the nails but do well on localized fungus on the body. Nevertheless, even on the body, these topical agents do not work as well as oral medications.

Ciclopirox olamine 8 percent is the only FDA-approved topical nail treatment. However, according to Dr. Daniel, the lacquer works less than 10 percent of the time on nails.

Another type of topical preparation that dermatologists use off label to treat fungus in the nails is 50 percent urea, in a vehicle containing lactic acid and zinc. Dr. Daniel may recommend that patients apply it to the nails in the morning, then use ciclopirox at night.

While these are today's options for fungal disease treatment, researchers are testing many other preparations, including nail lacquers and topical creams, in phase 3 trials, as well as oral medications, Dr. Daniel says.

In the meantime, his treatments of choice for dermatophyte infection of the nails are oral terbinafine and topical ciclopirox.