Paula Moyer is a medical writer based in Minneapolis, Minnesota.
Men do not get onychomychosis more frequently than do women, and the disease is no more severe than it is in female patients. Men may, however, be more likely than women to view the condition as cosmetic and, therefore, delay treatment, according to Nardo Zaias, M.D.
Miami Beach, Fla. - Men do not get onychomycosis more frequently than do women, and the disease is no more severe than it is in female patients. Men may, however, be more likely than women to view the condition as cosmetic and, therefore, delay treatment, according to Nardo Zaias, M.D.
Pulsed antimycotic therapy may be particularly appealing to male patients because of its simplicity and minimal intrusion into daily life, says Dr. Zaias, director of dermatology at Mount Sinai Medical Center, Miami Beach, Fla., and founder, the Greater Miami Skin and Laser Center.
The patient databases in onychomycosis research may have led dermatologists to view the condition as having unique features in male patients. However, that view is inaccurate, Dr. Zaias says.
“Most of studies have been done on groups of men, such as those serving in the armed forces,” he says. “Therefore, the patient databases have been predominantly male.”
Details show, however, that the unsightly fungal overgrowth plagues men and women fairly equally. “Susceptibility to onychomycosis is an autosomal dominant hereditary condition,” Dr. Zaias says. “It does not favor men over women. The fungus, Trichophyton rubrin, is already present.” However, certain factors such as the stress of combat may cause the organism to flourish and produce visible nail lesions.
Dr. Zaias questions the conventional wisdom about environmental factors such as wet feet causing the infection. He pointed to studies of indigenous people in arid climates who are typically barefoot, such as Native Americans in New Mexico.
“The incidence is the same,” he says. Instead, host factors can cause T. rubrum to flourish, such as a more robust autoimmune reaction, or the reverse, immunosuppression, as seen in patients with human immunodeficiency virus (HIV). That host response is unrelated to gender or to environmental factors, he adds.
Less is more
Because men are often reluctant to seek treatment for onychomycosis, the most definitive treatment should appeal to them because of its convenience, Dr. Zaias says.
“The best treatment to date is systemic antimycotic medication,” he says, adding that in his practice, he prefers terbinafine given in a pulsed manner. Patients can take a seven-day course consisting of 250 mg every three months until the nail bed is cured.
The reason that pulsed systemic therapy works is due to the slow growth of toenails and the ability of systemic antimycotics to deposit into the nail bed. “The toenail grows approximately 1 mm per month,” Dr. Zaias says. “Most toenails are 10 mm long.”
Interestingly, less appears to be more with systemic antimycotics and nail infections, he explains. When taken daily for three months, systemic therapy is associated with a cure rate of 50 to 60 percent. However, when patients who have diseased nails with at least 6 mm involvement, the drug deposits into the nail bed for three months, after which its potency declines.
“Pulsed therapy works in 100 percent of patients,” Dr. Zaias says.
Other antimycotics are associated with less robust results and a higher risk of adverse effects. Antimycotics in the imidazole class are metabolized on cytochrome 450 in the liver and therefore can interact with other drugs so metabolized, Dr. Zaias says. Terbinafine only interacts with warfarin.
Bed versus plate
Meanwhile, several investigative teams are still searching for an as-yet elusive topical therapy for onychomycosis. That search is challenging, Dr. Zaias says. “So far, not one that has been worthy of going out into the marketplace. Most of what’s out there doesn’t penetrate the nail bed. Most topical treatments are put on top of the nail plate as a lacquer.”
Because topical therapies have only been associated with a cure rate of 3 percent to 4 percent, a cure may call into question the diagnosis of onychomycosis, he says.
For more information:
Zaias N, Rebell G. Arch Dermatol. 2004;140(6):691-695.