Antifungal agents: An overview. Part I

How to improve cure rates for the management of onychomycosis

To improve the treatment of onychomycosis clinicians need to identify correctly the causative organism, choose a therapy that is effective against the pathogen, and take into consideration the pharmacokinetics (eg, bioavailability, drug interactions) of the oral agent. In addition, variations of the standard regimens may need to be considered (ie, booster or supplemental therapy). To reduce the recurrence of onychomycosis, once mycologic cure has been achieved, clinicians should educate their patients about proper foot care. Familiarity with the symptoms and signs of tinea pedis and onychomycosis may enable patients to seek appropriate care when the disease is at an early stage.

Treatments of tinea pedis

The severity of tinea pedis infection determines the course of treatment required. Mild infections may be resolved using a topical agent. More severe presentations (eg, dermatophytosis complex) may require treatment that eliminates the bacterial and fungal infection. Some topical monotherapies may exhibit both antifungal and antibacterial activity. In other instances, it may be necessary to combine an antifungal agent with an antibacterial agent. If inflammation is present, an agent with known anti-inflammatory action may need to be used. The chronic presentation of tinea pedis (dry type) sometimes does not respond well to topical therapy. In such instances, systemic antifungal therapy is required to ensure that adequate concentrations of the therapeutic agent are present at the site of infection.

New antifungal agents

Currently, use of standard antifungal therapies can be limited because of toxicity, low efficacy rates, and drug resistance. New formulations are being prepared to improve absorption and efficacy of some of these standard therapies. Various new antifungals have demonstrated therapeutic potential. These new agents may provide additional options for the treatment of superficial fungal infections and they may help to overcome the limitations of current treatments. Liposomal formulations of AmB have a broad spectrum of activity against invasive fungi, such as Candida spp., C. neoformans, and Aspergillus spp., but not dermatophyte fungi. The liposomal AmB is associated with significantly less toxicity and good rates of efficacy, which compare or exceed that of standard AmB. These factors may provide enough of an advantage to patients to overcome the increased costs of these formulations. Three new azole drugs have been developed, and may be of use in both systemic and superficial fungal infections. Voriconazole, ravuconazole, and posaconazole are triazoles, with broad-spectrum activity. Voriconazole has a high bioavailability, and has been used with success in immunocompromised patients with invasive fungal infections. Ravuconazole has shown efficacy in candidiasis in immunocompromised patients, and onychomycosis in healthy patients. Preliminary in vivo studies with posaconazole indicated potential use in a variety of invasive fungal infections including oropharyngeal candidiasis. Echinocandins and pneumocandins are a new class of antifungals, which act as fungal cell wall beta-(1,3)-D-glucan synthase enzyme complex inhibitors. Caspofungin (MK-0991) is the first of the echinocandins to receive Food and Drug Administration approval for patients with invasive aspergillosis not responding or intolerant to other antifungal therapies, and has been effective in patients with oropharyngeal and esophageal candidiasis. Standardization of MIC value determination has improved the ability of scientists to detect drug resistance in fungal species. Cross-resistance of fungal species to antifungal drugs must be considered as a potential problem to future antifungal treatment, and so determination of susceptibility of fungal species to antifungal agents is an important component of information in development of new antifungal agents. Heterogeneity in susceptibility of species to azole antifungals has been noted. This heterogeneity suggests that there are differences in activity of azoles, and different mechanisms of resistance to the azoles, which may explain the present lack of cross-resistance between some azoles despite apparent structural similarities. The mechanisms of azole action and resistance themselves are not well understood, and further studies into azole susceptibility patterns are required.

The use of oral antifungal agents to treat onychomycosis

Onychomycosis has been treated for years with oral antifungal agents, and more recently in the United States with a topical nail lacquer. Griseofulvin was the first significant oral agent available to manage onychomycosis. The introduction of the azoles (ketoconazole, itraconazole, and fluconazole) and the allylamine, terbinafine, led to improved cure rates and a broad spectrum of activity. Pharmacokinetic studies have shown that the newer oral agents penetrate the nail within approximately one to two weeks after the start of therapy and remain for several months after the end of treatment. This article reviews the oral antifungal agents used to treat onychomycosis.

Synthesis and antimycotic activity of N-azolyl-2,4-dihydroxythiobenzamides

N-pyrazole and N-1,2,4-triazole derivatives of 2,4-dihydroxythiobenzamide prepared from sulfinyl-bis-(2,4-dihydroxythiobenzoyl) and commercially available azole amines were tested for their antimycotic activity. The chemical structure of compounds was confirmed by IR, 1H NMR, MS and elemental analysis. The MIC values against the reference strain Candida albicans ATCC 10231, azole-resistant clinical isolates of Candida albicans and non-Candida albicans species were determined for their potential activity in vitro. The compounds exhibited comparable or higher activity than itraconazole and fluconazole tested under the same experimental conditions. Pyrazoline derivatives showed higher activity than other analogues. The strongest fungistatic activity for N-(2,3-dimethyl-1-phenyl-1,2-dihydro-5-oxo-5H-pyrazol-4-yl)-2,4-dihydroxythiobenzamide was found with MIC values significantly lower than those for the studied drugs.

Clinical pharmacology of antifungal compounds

Prompted by the worldwide surge in fungal infections, the past decade has witnessed a considerable expansion in antifungal drug research. New compounds have entered the clinical arena, and major progress has been made in defining paradigms of antifungal therapies. This article provides an up-to-date review on the clinical pharmacology, indications, and dosage recommendations of approved and currently investigational therapeutics for treatment of invasive fungal infections in adult and pediatric patients.

Onychomycosis: strategies to improve efficacy and reduce recurrence

Fungal infections may be difficult to treat for several reasons. It is important to obtain the correct diagnosis, and select the appropriate antifungal agent and route. General considerations that may be associated with recurrent infections are, a genetic predisposition and suboptimal bioavailability of drug, resulting in insufficient concentration at the target site. The aetiologic organism, the severity of disease, other coexisting diseases, concomitant drug intake, and the presence of fungal infection at other sites are some factors that determine the choice of antifungal therapy and its route of administration, oral vs. topical lacquer. Local factors such as the thickness of the nail, presence of lateral onychomycosis, longitudinal spike, dermatophytoma and severe onycholysis are some factors that may determine the choice of secondary measures such as mechanical or topical treatment. Booster or supplemental therapy may be of benefit when the response to initial treatment is poorer than expected and unlikely to result in complete response. Steps should be taken to reduce the possibility of recurrence once cure has been achieved.

Fluconazole mouthrinses for oral candidiasis in postirradiation, transplant, and other patients

OBJECTIVE

Oral candidiasis is associated with multiple local and systemic factors. Morbidity and deaths, in high-risk patients, may be prevented by recognition and adequate management. Fluconazole is a systemic antifungal medication that demonstrated clinical advantages in rinsing before swallowing. The purpose of the present study was to evaluate the clinical efficacy of fluconazole aqueous mouthrinses to treat oral candidiasis.

METHODS

Ten women and 9 men diagnosed with oral candidiasis used fluconazole (2 mg/mL) aqueous solution 3 times per day as a rinse and-spit topical treatment. The outcome was assessed after 1 week of treatment.

RESULTS

Complete symptomatic and clinical relief was noted in 94% of the patients, and a mycologic cure was documented in all but 1 patient. No side effects were reported. Oral rinses with fluconazole suspension may be useful to manage patients with dry mouth or those who have difficulties in swallowing caused by oral candidiasis.

CONCLUSIONS

Further double-blind studies are needed to establish the optimal treatment regimen and the usefulness of fluconazole mouthrinses in patients with different risk factors for infection.

In vitro susceptibility of Microsporum canis and other dermatophyte isolates from veterinary infections during therapy with terbinafine or griseofulvin

We investigated the in vitro activity of terbinafine against fresh veterinary isolates of Microsporum canis and the potential of this organism to develop resistance in vivo during oral therapy. Dermatophyte cultures (n = 300) were obtained from naturally infected cats and dogs undergoing oral therapy with terbinafine or griseofulvin. M. canis comprised 92% of isolates; other species included Microsporum gypseum and Trichophyton mentagrophytes. Minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) of terbinafine and griseofulvin were determined by broth macrodilution assay. Terbinafine was highly active against all three species with MIC90< or =0.03 microg ml(-1), in agreement with published data. However, terbinafine exhibited primary cidal activity against 66% of Microsporum isolates (n = 275) in contrast to the almost complete cidal effect in Trichophyton (n = 18). Griseofulvin was significantly less active than terbinafine (MIC90 = 4 microg ml(-1)) but had a primary cidal action on about 40% of the isolates. The data were analysed for changes in MIC and MFC during the course of therapy, which could be indicative for development of acquired resistance. Oral treatment of 37 animals with terbinafine for up to 39 weeks caused no increase in MIC or MFC of terbinafine, either in individual patients or in the whole group.

Oral treatments for fungal infections of the skin of the foot

BACKGROUND

About 15% of the population have fungal infections of the feet (tinea pedis or athlete's foot). Whilst there are many clinical presentations of tinea pedis the most common are between the toes (interdigital) and on the soles, heels and sides of the foot (plantar) which is known as moccasin foot. Once acquired the infection can spread to other sites including the nails, which can be a source of reinfection. Oral therapy is usually used for chronic conditions or when topical treatment has failed.

OBJECTIVES

To assess the effects and costs of oral treatments for fungal infections of the skin of the foot (tinea pedis).

SEARCH STRATEGY

Randomised controlled trials were identified from MEDLINE, EMBASE and CINAHL from the beginning of these databases to January 2000. We also searched the Cochrane Controlled trials Register (Cochrane Library issue 1, 2000) the Science Citation Index, BIOSIS, CAB-Health, Health star and Economic databases. Bibliographies were searched, podiatry journals hand searched and the pharmaceutical industry and schools of podiatry contacted.

SELECTION CRITERIA

Randomised controlled trials including participants who have a clinically diagnosed tinea pedis, confirmed by microscopy and growth of dermatophytes in culture.

DATA COLLECTION AND ANALYSIS

Study selection was done by two independent reviewers. Methodological quality assessment and data collection was also assessed by two independent reviewers.

MAIN RESULTS

Twelve trials, involving 700 participants, were included. The two trials comparing terbinafine and griseofulvin produced a pooled risk difference of 52% (95% confidence intervals 33% to 71%) in favour of terbinafine's ability to cure infection. No significant difference was detected between terbinafine and itraconazole; fluconazole and either itraconazole and ketoconazole; or between griseofulvin and ketoconazole, although the trials were generally small. Two trials showed that terbinafine and itraconazole were effective compared with placebo. Adverse effects were reported for all drugs, with gastrointestinal effects most commonly reported.

REVIEWER'S CONCLUSIONS

The evidence suggests that terbinafine is more effective than griseofulvin and that terbinafine and itraconazole are more effective than no treatment.

Variation in restriction fragment length polymorphisms among serial isolates from patients with Trichophyton rubrum infection

Molecular genotyping of strains of Trichophyton rubrum and T. mentagrophytes from patients with onychomycosis of the toes was performed to ascertain whether the fungal genotype changes over the course of time as sequential samples were obtained from patients receiving antifungal therapy and during follow-up. Sixty-six serial strains of T. rubrum and 11 strains of T. mentagrophytes were obtained from 20 patients (16 patients with T. rubrum, 4 with T. mentagrophytes) who were treated with oral antifungal therapy and observed over periods of up to 36 months. These strains were screened for genetic variation by hybridization of EcoRI-digested genomic DNAs with a probe amplified from the small-subunit (18S) ribosomal DNA and adjacent internal transcribed spacer regions. A total of five restriction fragment length polymorphism (RFLP) types were observed among 66 strains of T. rubrum. Two major RFLP types, differentiated by one band shift, represented 68% of the samples. None of the patients had a unique genotype. More than one RFLP type was often observed from a single patient (same nail) over a period of 1, 2, or 3 years, even in cases that did not appear cured at any time. Samples taken from different nails of the same patient had either the same or a different genotype. The genotypic variation did not correspond to any detectable phenotypic variation. Furthermore, no correlation was observed between the efficacy of the treatment administered and the genotype observed. While the DNA region studied distinguished among T. rubrum, T. mentagrophytes, and T. tonsurans, intraspecific RFLP variation was observed for T. rubrum and T. mentagrophytes strains. While independent multiple infection and coinhabitation of multiple strains may explain the presence of different genotypes in a nail, microevolutionary events such as rapid substrain shuffling, as seen in studies of repetitive regions in Candida species, may also produce the same result. The recovery of multiple strains during the course of sequential sampling of uncured patients further suggests that the typing system is not able to distinguish between relapse or reinfection, ongoing infection, and de novo infection.

The influence of antifungal drugs on virulence properties of Candida albicans in patients with diabetes mellitus

OBJECTIVE

This study investigated the influence of nystatin and fluconazole on virulence properties of Candida albicans.

STUDY DESIGN

A total of 108 diabetic patients participated in the study. Eighty-eight patients had clinical oral candidosis. Drug therapy was given at 6 hourly intervals for nystatin or daily with fluconazole for a maximum of 2 weeks. Adhesion of C albicans to buccal epithelial cells was determined by using an autologous adhesion assay prospectively over 6 months. Phospholipase production was estimated by using an agar plate method. The data analysis included a paired Student t test and calculation of correlation coefficients.

RESULTS

Unlike nystatin, treatment with fluconazole reduced the ability of C albicans to colonize the buccal mucosa for up to 8 weeks after the treatment. Patients without clinical signs of oral candidosis had significantly fewer C albicans isolates producing phospholipase than did patients with oral candidosis. Treatment with fluconazole, but not nystatin, reduced the production of phospholipase from C albicans oral isolates in patients with diabetes mellitus.

CONCLUSIONS

In addition to being antifungal, fluconazole alters phospholipase production, modifies buccal epithelial cells, and reduces adhesion of C albicans to human buccal epithelial cells for up to 8 weeks posttreatment in diabetic patients with oral candidosis.

Effect of sub-MICs of antimycotics on expression of intracellular esterase of Trichophyton rubrum

The electrophoretic pattern of the intracellular esterase of the dermatophyte Trichophyton rubrum was altered when this fungus was grown in the presence of subinhibitory concentrations of the antimycotics tioconazole or griseofulvin. All strains (original isolate and antimycotic resistant mutants) presented five clearly visible bands when cultivated on medium containing below-minimum inhibitory concentrations (sub-MICs) of tioconazole or griseofulvin, and only two clearly visible bands when cultivated in medium without antimycotics. No extra bands were detected in the electrophoretic patterns of the extracellular esterase of these fungi (mutants or the original isolate) when cultivated with or without tioconazole or griseofulvin (sub-MIC values). These results suggest that additional forms of esterase are produced inside the cell and may be a nonspecific response to cellular stress, or may participate in cellular detoxification processes in the presence of these antimycotics.

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.

Photosensitivity induced by oral itraconazole

A case of photosensitivity induced by itraconazole is reported. A 70-year-old woman had erythema, oedema and vesicles on sun-exposed areas after 5 days of itraconazole treatment for oral candidiasis. Oral photochallenge using itraconazole and sun irradiation was positive, but photopatch test was negative. Photosensitivity from azoles is an uncommon adverse effect. Only three other cases have been described, two induced by ketoconazole and one by itraconazole.

Pharmacoeconomic analysis of ciclopirox nail lacquer solution 8% and the new oral antifungal agents used to treat dermatophyte toe onychomycosis in the United States

BACKGROUND

Recently a novel topical nail lacquer, ciclopirox solution 8%, has been approved for the treatment of onychomycosis.

OBJECTIVE

This was undertaken to determine the most cost-effective treatment for the treatment of dermatophyte onychomycosis of the toes in the United States in 2000.

METHODS

The nature of the problem was defined. The drug comparators were ciclopirox nail lacquer, terbinafine, itraconazole (pulse), itraconazole (continuous), fluconazole, and griseofulvin. A decision analytic model that reflected the manner in which pedal tinea unguium is managed was produced. Studies that have evaluated the efficacy of the nail lacquer and the oral antifungal agents for this indication were identified. Appropriate studies were used in a meta-analysis to determine the mycologic and clinical response rates when the drug comparators are used for the treatment for toe dermatophyte onychomycosis. For each drug comparator a cost of regimen analysis was carried out. This is the sum of the drug acquisition cost, the cost of medical management, and the cost of managing adverse effects. Next, the expected cost of management was calculated, disease free days were determined, and a sensitivity analysis was conducted.

RESULTS

For each comparator the meta-analytic average mycologic cure (MC) rate and clinical response (CR) rates were: ciclopirox nail lacquer (MC: 52.6 +/- 4.2%, CR: 52.4 +/- 9.0%), griseofulvin (MC: 41.1 +/- 20.4%, CR: 33.7 +/- 14.1%), itraconazole (continuous) (MC: 66.3 +/- 4.2%, CR: 70.3 +/- 4.2%), itraconazole (pulse) (MC: 70.8 +/- 5.7%, CR: 73.6 +/- 4.6%), terbinafine (MC: 77.2 +/- 4.0%, CR: 75.3 +/- 2.9%), and fluconazole (MC: 65.6 +/- 7.1%, CR: 66.5 +/- 11.7%). The cost of regimen for the drug comparators was: ciclopirox nail lacquer $325.2, griseofulvin $1413.1, itraconazole (continuous) $1410.2, itraconazole (pulse) $811.7, terbinafine $890.1, and fluconazole $966.8. The cost/mycologic cure rate and expected cost/expected symptom free day were, ciclopirox nail lacquer ($618.2, 1.69), griseofulvin $3438.2, 5.3), itraconazole (continuous) ($2126.9, 3.52), itraconazole (pulse) ($1146.4, 2.01), terbinafine ($1153.0, 2.14), and fluconazole ($1473.7, 2.10). The relative cost-effectiveness was ciclopirox nail lacquer 1.00, itraconazole (pulse) 1.19, fluconazole 1.24, terbinafine 1.27, itraconazole (continuous) 2.08, and griseofulvin 3.13. Sensitivity analysis indicated that ciclopirox nail lacquer was a cost effective alternative compared with the oral regimens of terbinafine, itraconazole (continuous), and griseofulvin when clinical response rate was used as the primary efficacy parameter.

CONCLUSION

Ciclopirox nail lacquer solution 8% is a recent addition to the armamentarium of therapies available to the physician and patient for the treatment of onychomycosis. The nail lacquer is a cost effective agent compared with the oral antifungal therapies, terbinafine, itraconazole, fluconazole, and griseofulvin.

Ciclopirox nail lacquer topical solution 8% in the treatment of toenail onychomycosis

BACKGROUND

Onychomycosis is a relatively common condition affecting toenails more than fingernails. It is caused predominantly by dermatophytes. Onychomycosis can cause pain and discomfort and has the potential to be a source of morbidity.

OBJECTIVE

We evaluated the efficacy and safety of ciclopirox nail lacquer solution 8% used to treat onychomycosis of the toe in the United States and in centers worldwide.

METHODS

Two identically designed, double-blind, vehicle controlled, parallel group multicenter studies were performed in the United States to evaluate the use of ciclopirox nail lacquer to treat mild to moderate toe onychomycosis caused by dermatophytes. In the first study, 223 patients were randomized to treatment (ciclopirox group: 112, vehicle group: 111), and in the second study, 237 subjects were randomized (ciclopirox group: 119, vehicle group: 118). Before randomization, patients were to have clinical features of onychomycosis in at least one great toe with positive light microscopic examination and a positive dermatophyte culture. The test material was applied daily for a period of 48 weeks to all toenails and affected fingernails, covering the entire nail plate and approximately 5 mm of surrounding skin. At baseline, subjects had between 20% to 65% area of target nail involved. Physician's assessments were carried out every 4 weeks, and mycologic evaluation and photographic planimetry using standardized photographs were performed every 12 weeks during the 48 weeks of treatment. In studies conducted outside the United States, patients were also to have clinical, microscopic, and culture evidence of onychomycosis. However, these studies included some patients infected with nondermatophyte organisms (eg, Candida species), and the area of nail involvement was generally greater than observed in the US studies. Treatment regimens also varied in the non-US studies with lacquer applications that were sometimes less frequent than the once daily treatment used in the US studies (eg, alternate day or twice weekly). In addition, the typical duration of treatment was 6 months in the non-US studies as compared with 48 weeks in the United States. Outcome measures were similar to those used in the US trials, although a non-photographic planimetric method was used to quantify disease extent.

RESULTS

Data from the pivotal US trials have demonstrated that ciclopirox nail lacquer 8% topical solution is significantly more effective than placebo in the treatment of onychomycosis caused by Trichophyton rubrum, and of mild to moderate toe onychomycosis without lunula involvement. At the end of the 48-week treatment period, the mycologic cure rate (negative culture and negative light microscopy) in study I was 29% vs 11% in the ciclopirox and vehicle groups, respectively. Similarly, the mycologic cure rate for study II was 36% vs 9%, respectively. In the non-US studies, the mycologic cure rates ranged from 46.7% to 85.7%. In addition, ciclopirox nail lacquer has demonstrated a broad spectrum of activity with efficacy against Candida species and some nondermatophytes in non-US studies. Ciclopirox nail lacquer is considered extremely safe regarding causally related treatment emergent adverse-effects (TEAEs), with most TFAEs transient and localized to the site of action (eg, erythema and application site reaction). In the US studies, TFAEs were generally mild and cleared while the patient continued to use the nail lacquer.

CONCLUSIONS

Studies conducted worldwide demonstrate the efficacy of ciclopirox nail lacquer for the treatment of finger and toe onychomycosis. Both controlled and open-label studies confirm the excellent safety profile of this topical therapy. Thus, the nail lacquer provides a treatment choice with a favorable benefit-to-risk ratio. With its novel mechanism of action and its topical route of administration, ciclopirox nail lacquer offers an innovative approach to the treatment of this often difficult-to-manage disease

Ciclopirox nail lacquer solution 8% in the 21st century

Ciclopirox nail lacquer solution 8% has been shown to be effective in the treatment of dermatophyte onychomycosis of mild to moderate severity Other studies report the effectiveness of ciclopirox nail lacquer in onychomycosis caused by Candida sp and nondermatophyte molds. Ciclopirox nail lacquer may also be valuable in the treatment of early cases of reinfection/relapse. Ciclopirox nail lacquer solution 8% may be an important adjunct to oral antifungal therapy in certain presentations that might be poorly responsive to oral antifungal therapy alone (eg, lateral onychomycosis, longitudinal spike, dermatophytoma, and extensive onycholysis). In some cases, surgical therapies may need to be considered in addition to, or in preference to, topical nail lacquer treatment. The use of ciclopirox nail lacquer solution 8% as an adjunct to oral antifungal therapy may widen the spectrum of activity of the combination because of the broad spectrum of coverage provided by the lacquer. The use of combination therapy may be synergistic in terms of efficacy, enabling a reduction in the duration and cumulative dosage of oral therapy. This could result in a decrease in the frequency and severity of systemic adverse effects associated with the oral antimycotics and the need to be vigilant about drug interactions. Studies need to be conducted to determine the place of combination oral and topical lacquer therapy in the management of onychomycosis.

Voriconazole: a new triazole antifungal

OBJECTIVE

To review the currently available information on the pharmacology, pharmacokinetics, efficacy, adverse effects, drug interactions, and dosage guidelines of voriconazole. Comparative data for voriconazole and other azole antifungal agents are described where available.

DATA SOURCES

A MEDLINE search restricted to English-language articles (1966 to September 1999) was conducted, and an extensive review of journals and meeting abstracts was performed. MeSH headings included itraconazole, fluconazole, voriconazole, UK-109,496, and amphotericin B.

DATA EXTRACTION

The data on pharmacokinetics, adverse effects, and drug interactions were obtained from open-label and controlled studies and case reports. Controlled studies and case reports were evaluated to demonstrate the efficacy of voriconazole in treatment of various fungal infections.

DATA SYNTHESIS

Voriconazole is a derivative of fluconazole that demonstrates enhanced in vitro activity against existent and emerging fungal pathogens. Limited data have revealed a favorable pharmacokinetic and safety profile for the agent. Moreover, select clinical trials and case studies of voriconazole suggest good in vivo efficacy against several fungal pathogens including Candida, Aspergillus, and Scedosporium.

CONCLUSIONS

Voriconazole has shown promise in the treatment of superficial and systemic mycoses. While several unresolved issues remain, voriconazole may be a viable therapeutic alternative for fluconazole-resistant mucocutaneous candidiasis and in cases of mild to moderate systemic mycoses requiring chronic treatment or that are refractory to currently available agents.

Tinea capitis

Tinea capitis is a common dermatophyte infection of the scalp in children. Dermatophytes are classified into three genera; tinea capitis is caused predominantly by Trichophyton or Microsporum species. On the basis of host preference and natural habitat, dermatophytes are also classified as anthropophilic, geophilic and zoophilic. The etiological agents of tinea capitis usually fall in the first and last categories. In North America, tinea capitis is now predominantly due to Trichophyton tonsurans. During the past 100 years the most common North American organism for tinea capitis was initially Microsporum canis followed later by M. audouinii. In other parts of the world the epidemiology varies. Tinea capitis is generally observed in children over the age of 6 years and before puberty, with African Americans being the most affected group. Clinical presentations are seborrheic-like scale, 'black dot' pattern, inflammatory tinea capitis with kerion and tiny pustules in the scalp. The clinical diagnosis should be confirmed by mycological examination. Wood's light examination was of value in diagnosing tinea capitis due to M. canis and M. audouinii; however, it is not helpful in T. tonsurans tinea capitis. Asymptomatic carriers may be a significant reservoir of infection and spread of spores may also involve inanimate objects. Carriers may benefit from shampooing their hair. Treatment of tinea capitis requires an oral antifungal agent. The data from the use of terbinafine, itraconazole and fluconazole are promising and suggest that these agents have an efficacy similar to griseofulvin while shortening the duration of therapy. Both griseofulvin and the newer antimycotics have a favorable adverse-effect profile and are associated with high compliance.

Onychomycosis in children: treatment with bifonazole-urea

We assessed the safety and efficacy of a two-phase topical treatment with bifonazole-urea ointment in children with onychomycosis. Twenty-five children younger than 16 years old with proved onychomycosis were included in the study. Bifonazole-urea ointment was administered under occlusion until the nontraumatic removal of the nail was achieved. Bifonazole cream was then applied for 4 weeks and a follow-up visit 4 weeks after cessation of medication was scheduled. During the study, periodic clinical and mycologic evaluations were carried out. Of the 25 patients included, 17 were cured (68%), 6 improved, and 2 failed treatment. The main etiologic agent isolated was Trichophyton rubrum (92%). Two patients had minor side effects, both during the occlusive phase, one each with mild pain and a probable dermatitis from the adhesive strips. Treatment was not discontinued in both of these cases. We concluded that a two-phase treatment with bifonazole-urea is effective and safe, and represents a new therapeutic choice for onychomycosis in children.

Fungal skin disorders

Fungal skin infections are becoming more common, and primary care physicians must be familiar with the diagnosis and treatment of these disorders. Dermatophyte infections including tinea pedis, corporis and cruris; pityriasis versicolor; and cutaneous candidiasis are the focus of this article. Common presentations of these disorders, the differential diagnosis, and current treatments are stressed. With the newer agents, shorter treatment courses can be used, and oral therapy for widespread, resistant, or recurrent infections is discussed.

Tinea capitis: current concepts

Tinea capitis is an important fungal infection that may at times be a clinical, diagnostic and therapeutic challenge. It is common in childhood around the world, becoming almost epidemic in some communities. The central European and American experience with it is somewhat variable, due to different etiologic fungi. The use of topical antifungal agents and other approaches is stressed as of value alongside the use of systemic antifungal medication.

Comparison of terbinafine and griseofulvin in the treatment of tinea capitis

BACKGROUND

Griseofulvin has been used for many years in the treatment of tinea capitis. Increase in resistance to this medication has led to a search for new therapeutic alternatives.

OBJECTIVE

Our purpose was to evaluate the therapeutic efficacy of terbinafine in comparison with griseofulvin in the treatment of tinea capitis.

METHODS

We performed a double-blind, randomized, prospective evaluation of 50 patients with a clinical and mycologic diagnosis of tinea capitis. One group received 4 weeks of terbinafine followed by 4 weeks of placebo. The other group received 8 weeks of griseofulvin. We evaluated 5 clinical parameters. Mycologic examinations were performed at baseline and at the end of weeks 8 and 12.

RESULTS

Patients' ages ranged from 1 to 14 years. Fifty-four percent were girls and 46% were boys. Mycologic examinations disclosed Trichophyton tonsurans in 74% of patients and Microsporum canis in 26%. At week 8, the griseofulvin-treated group showed a cure rate of 76%, and the terbinafine-treated group 72%. At week 12, the efficacy of griseofulvin decreased to 44%, whereas the efficacy of terbinafine was 76%.

CONCLUSION

Terbinafine constitutes an alternative for the treatment of tinea capitis. Recurrences were less frequent. No significant side effects were reported.

A risk-benefit assessment of the newer oral antifungal agents used to treat onychomycosis

The newer antifungal agents itraconazole, terbinafine and fluconazole have become available to treat onychomycosis over the last 10 years. During this time period these agents have superseded griseofulvin as the agent of choice for onychomycosis. Unlike griseofulvin, the new agents have a broad spectrum of action that includes dermatophytes, Candida species and nondermatophyte moulds. Each of the 3 oral antifungal agents, terbinafine, itraconazole and fluconazole, is effective against dermatophytes with relatively fewer data being available for the treatment of Candida species and nondermatophyte moulds. Itraconazole is effective against Candida onychomycosis. Terbinafine may be more effective against C. parapsilosis compared with C. albicans; furthermore with Candida species a higher dose of terbinafine or a longer duration of therapy may be required compared with the regimen for dermatophytes. The least amount of experience in treating onychomycosis is with fluconazole. Griseofulvin is not effective against Candida species or the nondermatophyte moulds. The main use of griseo-fulvin currently is to treat tinea capitis. Ketoconazole may be used by some to treat tinea versicolor with the dosage regimens being short and requiring the use of only a few doses. The preferred regimens for the 3 oral antimycotic agents are as follows: itraconazole - pulse therapy with the drug being administered for 1 week with 3 weeks off treatment between successive pulses; terbinafine - continuous once daily therapy; and fluconazole - once weekly treatment. The regimen for the treatment of dermatophyte onychomycosis is: itraconazole - 200mg twice daily for I week per month x 3 pulses; terbinafine - 250 mg/day for 12 weeks; or, fluconazole - 150 mg/wk until the abnormal-appearing nail plate has grown out, typically over a period of 9 to 18 months. For the 3 oral antifungal agents the more common adverse reactions pertain to the following systems, gastrointestinal (for example, nausea, gastrointestinal distress, diarrhoea, abdominal pain), cutaneous eruption, and CNS (for example, headache and malaise). Each of the new antifungal agents is more cost-effective than griseofulvin for the treatment of onychomycosis and is associated with high compliance, in part because of the shorter duration of therapy. The newer antifungal agents are generally well tolerated with drug interactions that are usually predictable.

Pustular tinea pedis

Pustules are uncommon in tinea pedis and may suggest a bacterial infection. We describe a patient with large pustules on his feet that contained hyphae on Gram's stain of the pus and on a potassium hydroxide preparation of the pustule roof. Cultures were negative for bacteria, but grew Trichophyton rubrum.

Tinea capitis: a current perspective

During the past 50 years, the predominant etiologic agent of tinea capitis in the United States and in Western Europe has changed from Microsporum audouinii to Trichophyton tonsurans. This is thought to be due in part to the sensitivity of M audouinii to griseofulvin treatment and, in part, due to the importing of T tonsurans by people emigrating from geographic areas where that vector had been the prominent cause of tinea capitis. With these changes, prospects for newer therapies with the novel antimycotic agents itraconazole, fluconazole, and terbinafine are reviewed. (J Am Acad Dermatol 2000;42:1-20.)

LEARNING OBJECTIVE

At the conclusion of this learning activity, participants should be familiar with the history, epidemiology, and current knowledge of tinea capitis, as well as the newer antifungal agents (ie, itraconazole, fluconazole, and terbinafine) to treat this infection.

Tinea capitis: an overview with emphasis on management

Tinea capitis is perhaps the most common mycotic infection in children. In North America the epidemiology of tinea capitis has changed so that Trichophyton tonsurans now predominates over Micro-sporum audouinii. With this transition the utility of the Wood's light for diagnosis has been reduced since T. tonsurans infection is Wood's light negative. Griseofulvin has been the mainstay of therapy for the last 40 years. The newer antifungal agents-itraconazole, terbinafine, and fluconazole-appear to be effective and safe for the treatment of tinea capitis. When tinea capitis is due to T. tonsurans or other endothrix species the following regimens have been used: itraconazole continuous regimen (5 mg/kg/day for 4 weeks), itraconazole pulse regimen with capsules (5 mg/kg/day for 1 week plus 1-3 pulses 3 weeks apart), and itraconazole pulse regimen with oral solution (3 mg/kg/day for 1 week plus 1-3 pulses 3 weeks apart). With terbinafine tablets the continuous regimen (>40 kg body weight, 250 mg/day; 20-40 kg, 125 mg/day; and <20 kg, 125 mg/day) is given for 2 to 4 weeks. Fluconazole tablets or oral suspension (6 mg/kg/day) were administered for 20 days in one trial. Another possibility may be 6 mg/kg/day for 2 weeks and evaluating the scalp 4 weeks later. An extra week of therapy (6 mg/kg/day) can be administered if clinically indicated at that time. A once-weekly regimen may also be effective. When ectothrix organisms (e.g., Microsporum canis) are present, a longer duration of therapy may be required. The data suggest that the newer agents are effective, safe with few adverse effects, and have a high benefit:risk ratio. It remains to be seen to what extent griseofulvin will be superseded for the treatment of tinea capitis. Adjunctive therapies may help decrease the risk of infection to other individuals. Appropriate measures should be taken to reduce the possibility of reinfection.

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.

Factors that may affect the response of onychomycosis to oral antifungal therapy

With the advent of the newer oral antifungals available to treat onychomycosis, the majority of patients respond to therapy. However, there may be subsets of patients who exhibit poor response or failure. Possible explanations for this may be grouped into categories, including: (i) patient characteristics; (ii) organisms causing or associated with the nail infection; (iii) nail characteristics; and (iv) local diseases involving the nail.

Dermatology therapy update

New treatments for skin disease continue to evolve. This article summarizes recent advances in dermatologic therapy and suggests various alternative approaches for situations in which more conventional modalities are unavailable, ineffective, or contraindicated.

Pediatric antifungal therapy

The most common superficial dermatophyte infections in children involve the scalp, skin, and nails. Griseofulvin has traditionally served as the standard of care for scalp and nail infections, but an increasing proportion of tinea capitis infections are proving refractory or very slowly responsive to treatment. This article will review new antifungal therapies available and their future role in the treatment of pediatric dermatophyte infections. As these new agents are not yet FDA approved for use in the pediatric dermatophyte infections, the practitioner must be aware of possible risks and benefits of such drugs, and counsel families appropriately regarding "off-label" use.

A questionnaire study on the management of onychomycosis: a Canadian perspective

BACKGROUND

Onychomycosis of the toenails is a condition that responds poorly to griseofulvin. The introduction of terbinafine in Canada in May 1993 resulted in a marked shift in the choice of treatment for pedal onychomycosis.

METHODS

A questionnaire survey was carried out in 1996 among Canadian dermatologists regarding the management of onychomycosis.

RESULTS

There were 160 respondents from the roughly 350 practicing dermatologists. The dermatologists saw 8 +/- 0.6 patients per week (average +/- standard error (SE) with suspected or diagnosed onychomycosis, with 5 +/- 0.5 patients per week consulting the dermatologists for the first time. Most dermatologists performed mycological testing prior to starting treatment for onychomycosis. The management options for onychomycosis (mean +/- SE) were oral systemic antifungal therapy 51 +/- 3%, no therapy 31 +/- 3%, and nondrug therapy 9 +/- 2%. The majority of dermatologists (83%) used terbinafine as first-line therapy if, indeed, they used oral antifungal agents. In contrast, griseofulvin and ketoconazole were used as first-line therapy in 5% and 1% of cases, respectively. In Canada, there are no monitoring requirements when using oral terbinafine for onychomycosis. Therefore, it is not surprising that only 30% of dermatologists performed monitoring with terbinafine. In contrast, the frequency of monitoring with griseofulvin and ketoconazole was 40% and 80%, respectively. The subset of dermatologists who reported monitoring carried it out in only a fraction of their patients: 47%, 53% and 83% for terbinafine, griseofulvin, and ketoconazole, respectively. Therefore, the overall number of patients in whom regular monitoring was performed was 14.1% 21.2%, and 71.4% for terbinafine, griseofulvin, and ketoconazole, respectively. The perceived cure rates with terbinafine and griseofulvin (mean +/- SE) were 83.7 +/- 1% and 41 +/- 3.1%, respectively.

CONCLUSIONS

In May 1996, within three years of the introduction of terbinafine to Canada, this agent has become the drug of choice for the treatment of pedal onychomycosis (at the time of the survey neither itraconazole or fluconazole were approved for onychomycosis). Terbinafine has been found to be very effective and safe, and only a minority of dermatologists perform regular monitoring with this drug.

Oropharyngeal candidiasis: a review of its clinical spectrum and current therapies

With the increased use of antibiotics and immunosuppressive agents, oropharyngeal candidiasis is becoming more common. This infection is also associated with such advances in medical management as chemotherapy and organ transplantation and with human immunodeficiency virus infection. Various topical and systemic agents are available to treat patients with candidiasis, but optimal management can be elusive. Treatment of uncomplicated oropharyngeal candidiasis in the immunocompetent patient involves selecting a particular formulation of a topical medication based on oral conditions, length of contact time, and taste, texture, and cost of the medication. Treatment of severe oropharyngeal candidiasis, particularly in patients with a compromised immune system, is often more difficult, and relapses are common. Reports of resistance to systemic agents, particularly in patients needing recurrent therapy, are increasing. Amphotericin B, long used as an intravenous agent, is now available as an oral suspension that may offer therapeutic benefits comparable to those of systemic therapy without the toxicity associated with systemic absorption.

Interactions between amphotericin B and nitroimidazoles against Candida albicans

This work proved that nitroimidazole antiprotozoal agents, such as metronidazole, ornidazole, secnidazole and tinidazole, in concentrations of up to 64 micrograms ml-1 did not present any antifungal activity against 17 strains of Candida albicans. The combination of each drug with amphotericin B showed the occurrence of variable interactions according to the studied strain. Promising results were observed based on synergistic and additive interactions of the polyene with the metronidazole; the inhibitory and lethal activities of the drugs were potentiated against all strains in concentrations reachable in vivo.

Superficial fungal infections. Errors to avoid in diagnosis and treatment

Superficial fungal infections are easily managed once the proper diagnosis is made. However, misdiagnosis is not uncommon, and many standard approaches to treatment popular just a few years ago are now out of date or in need of refinement. Through nine illustrative cases, the authors describe pitfalls in diagnosis and treatment of common fungal infections involving the skin, hair, and nails.