Recent developments in antifungal therapy

In vitro antifungal susceptibility testing of fungi in patients with onychomycosis

Onychomycosis is the most common nail disorder. To examine in vitro antifungal susceptibility of fungi among onychomycosis patients. The study included 68 patients with onychomycosis. Nail specimens were cultured on Sabouraud dextrose agar and Dermasel agar base-media. Isolated fungi were subjected to antifungal susceptibility tests against terbinafine, itraconazole, fluconazole, and griseofulvin. Candida species (Candida spp.) were detected in 32.4% of the cases of candidal onychomycosis (n = 37), 23.5% of the cases of distal and lateral subungual onychomycosis (n = 17), and 21.4% of the cases of total dystrophic onychomycosis (n = 14). Candida spp. were sensitive to fluconazole in 73.5%, itraconazole in 58.8%, and terbinafine in 5.9% of the cases. Aspergillus spp. were sensitive to itraconazole in all cases, and terbinafine in 87.5% of cases. Penicillium spp. were sensitive to itraconazole and terbinafine in 88.9% and 77.8% of cases, respectively. Trichophyton spp. were sensitive to terbinafine and resistant to itraconazole. Microsporum spp. were sensitive to itraconazole and resistance to terbinafine. All isolated fungi were resistant to griseofulvin. An increasing proportion of Candida spp. was observed among patients with different clinical varieties of onychomycosis. Candida spp. were highly sensitive to fluconazole and a lesser extent to itraconazole.

Systemic antifungal therapy

Systemic antifungal therapy for superficial mycoses has advanced greatly since the introduction of griseofulvin in 1958. The discovery of the azole antifungal compounds, ketoconazole, itraconazole, and fluconazole, allowed for a broader spectrum of treatment and a shorter treatment duration. Terbinafine, through a unique mechanism of action, has a fungicidal power not seen previously in the other antifungals. It is important to use our knowledge of the pharmacology in combination with clinical experience and cost of therapy in order to select the proper drug. The search to identify new oral antifungal agents should continue, since none of the five currently used drugs fulfill the criteria of the "ideal" antifungal.

Which antifungal agent for onychomycosis? A pharmacoeconomic analysis

The incidence of fungal nail infections is increasing and this is possibly because of several factors: better methods of detection, a growing population of immunocompromised patients who have a greater susceptibility to such infections, the increased use of immunosuppressive drugs, the increasing number of elderly people, worldwide travel, and the use of communal bathing facilities. Onychomycosis is a fungal infection of the fingernails and toenails that accounts for about 30% of all superficial fungal infections. It is characterised by nail discoloration, thickening and ultimately destruction of the nail plate. Management of this disease has improved significantly and treatment patterns have dramatically changed in recent years as a result of advances in new treatment options (e.g. oral antifungal agents) and changes in treatment regimens (e.g. pulse therapy). Also, newer drugs for onychomycosis have improved tolerability profiles compared with older agents. The overall costs of treating onychomycosis are substantial, and it has been estimated that direct cost for US Medicare patients with the disease is 43 million US dollars per year (year of costing not available). Pharmacoeconomic studies help in the decision-making process when selecting the most cost-effective antifungal agents to treat onychomycosis. To date there have been a number of national and international economic studies aimed at effectively assessing the efficacy and costs of the treatment options available to cure onychomycosis. The objectives of this paper are to (i) review the published findings regarding the epidemiology of onychomycosis; (ii) summarise the original pharmacoeconomic studies that describe the economic impact of the disease; and (iii) address the impact of the disease on patients' health-related quality of life.

Comparison of the therapeutic efficacy of oral doses of fluconazole and itraconazole in a guinea pig model of dermatophytosis

The therapeutic efficacy of orally administered fluconazole (FLCZ) and itraconazole (ITCZ) in a guinea pig model of dermatophytosis was compared, using the infection intensity of local skin tissue as an index. After Trichophyton mentagrophytes infections had been established in the test animals, the antifungal agents were administered once per day for 14 days. FLCZ had a dose-dependent therapeutic effect and significantly ameliorated infections at doses of 10 and 20 mg/kg per day (both P < 0.01) compared with the untreated control group. The pathogen could not be cultured from previously infected skin tissue from 11% of the animals treated with FLCZ at 10 mg/kg per day, and from 20% of the animals treated with FLCZ at 20 mg/kg per day. The therapeutic efficacy of FLCZ was approximately equal to that of ITCZ administered at the same doses. These results suggest that FLCZ may be a useful treatment for dermatophytosis.

Oral therapy of common superficial fungal infections of the skin

Although superficial fungal infections of the skin often respond to topical agents, systemic therapy is sometimes necessary. This article gives a review of the effectiveness of the oral antifungal agents fluconazole, itraconazole, and terbinafine in the treatment of pityriasis versicolor, tinea corporis/cruris, and tinea pedis. Four hundred milligrams fluconazole as a single dose and 200 mg itraconazole daily for 5 to 7 days were effective in the treatment of pityriasis versicolor; terbinafine taken orally appears to be ineffective in pityriasis versicolor. Tinea corporis and tinea cruris were effectively treated by 50 to 100 mg fluconazole daily or 150 mg once weekly for 2 to 3 weeks, by 100 mg itraconazole daily for 2 weeks or 200 mg daily for 7 days, and by 250 mg terbinafine daily for 1 to 2 weeks. Tinea pedis has been effectively treated with pulse doses of 150 mg fluconazole once weekly, with 100 mg itraconazole daily for 2 weeks or 400 mg daily for 1 week, and with 250 mg terbinafine daily for 2 weeks.

Current and emerging azole antifungal agents

Major developments in research into the azole class of antifungal agents during the 1990s have provided expanded options for the treatment of many opportunistic and endemic fungal infections. Fluconazole and itraconazole have proved to be safer than both amphotericin B and ketoconazole. Despite these advances, serious fungal infections remain difficult to treat, and resistance to the available drugs is emerging. This review describes present and future uses of the currently available azole antifungal agents in the treatment of systemic and superficial fungal infections and provides a brief overview of the current status of in vitro susceptibility testing and the growing problem of clinical resistance to the azoles. Use of the currently available azoles in combination with other antifungal agents with different mechanisms of action is likely to provide enhanced efficacy. Detailed information on some of the second-generation triazoles being developed to provide extended coverage of opportunistic, endemic, and emerging fungal pathogens, as well as those in which resistance to older agents is becoming problematic, is provided.