Clinical pearl: systemic antifungal drugs and drug interactions

Central nervous system paracoccidioidomycosis. Report of a case successfully treated with itraconazol

Paracoccidioidomycosis (PCM) is a primary pulmonary infection that often disseminates to other organs and systems. Involvement of the central nervous system (CNS) is rare and due to the fact that both clinical alertness and establishment of the diagnosis are delayed, the disease progresses causing serious problems. We report here a case of neuroparacoccidioidomycosis (NPCM), observed in a 55 year-old male, who consulted due to neurological symptoms (left hemiparesis, paresthesias, right palpebral ptosis, headache, vomiting and tonic clonic seizures) of a month duration. Upon physical examination, an ulcerated granulomatous lesion was observed in the abdomen. To confirm the diagnosis a stereotactic biopsy was taken; additionally, mycological tests from the ulcerated lesion and a bronchoalveolar lavage were performed. In the latter specimens, P. brasiliensis yeast cells were visualized and later on, the brain biopsy revealed the presence of the fungus. Treatment with itraconazole (ITZ) was initiated but clinical improvement was unremarkable; due to the fact that the patient was taking sodium valproate for seizure control, drug interactions were suspected and confirmed by absence of ITZ plasma levels. The latter medication was changed to clonazepam and after several weeks, clinical improvement began to be noticed and was accompanied by diminishing P. brasiliensis antigen and antibody titers. In the PCM endemic areas, CNS involvement should be considered more often and the efficacy of itraconazole therapy should also be taken into consideration.

A double-blind, randomized study to compare the efficacy and safety of terbinafine (Lamisil) with fluconazole (Diflucan) in the treatment of onychomycosis

In a randomized, double-blind, double-placebo, multicentre study, terbinafine 250 mg daily for 12 weeks was compared with fluconazole 150 mg once weekly for 12 or 24 weeks in the treatment of onychomycosis. A total of 137 patients with culture-confirmed onychomycosis was divided into three groups: group A received terbinafine for 12 weeks, group B received fluconazole for 12 weeks, while group C received fluconazole for 24 weeks. At completion of the study (week 60), the mycological cure rate was higher in the terbinafine group than in the fluconazole groups: 89% vs. 51% and 49%, respectively (P < 0.001). The length of unaffected nail increased until week 24 in group B and until week 36 in group C, but was still increasing in group A at the final visit (week 60). Complete clinical cure of the target nail at week 60 was 67% in the terbinafine group, compared with 21% and 32% in the fluconazole groups, respectively. The incidence of adverse events was low for both study agents. We conclude that terbinafine 250 mg daily for 12 weeks is significantly more effective in the treatment of onychomycosis than fluconazole 150 mg once weekly for either 12 or 24 weeks.

Drug interactions of the newer oral antifungal agents

The newer oral antifungal agents, such as fluconazole, itraconazole and terbinafine, are generally both effective and well tolerated in the management of widespread or resistant dermatomycoses such as onychomycosis. However, these agents differ markedly in their potential to cause clinically significant drug interactions. Triazoles such as fluconazole and itraconazole have been responsible for a greater number of clinically significant drug interactions than terbinafine. For example, itraconazole, and to a lesser extent fluconazole (in high doses) are inhibitors of CYP3A4. Therefore certain agents that are substrates of this enzyme, such as some of the new generation of H1-antihistamines, several HMG-CoA reductase inhibitors and certain benzodiazepines, are contraindicated. Other drugs like cyclosporine and quinidine need careful monitoring if administered concurrently with these triazoles. In contrast, there are no drug-drug contraindications with terbinafine. Indeed, in a postmarketing surveillance study, in which 42.8% of the 25,884 participating patients were taking a variety of concomitant therapies, no new drug-drug interactions were revealed. Physicians should be aware of the potential for interaction of the medications that they prescribe, in order to prevent or reduce the burden of adverse events. Terbinafine may be the most rational choice of oral antifungal agent in patients receiving concomitant medications that may adversely affect or be affected by either fluconazole or itraconazole.

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.

Antigenemia in patients with paracoccidioidomycosis: detection of the 87-kilodalton determinant during and after antifungal therapy

Serological diagnosis and follow-up of paracoccidioidomycosis (PCM) patients have relied mainly on the detection of antibody responses by using techniques such as complement fixation (CF) and immunodiffusion. We recently described a novel inhibition enzyme-linked immunosorbent assay (inh-ELISA) which proved to be useful in the diagnosis of PCM via the detection of an 87-kDa determinant in patient sera (B. L. Gomez, J. I. Figueroa, A. J. Hamilton, B. Ortiz, M. A. Robledo, R. J. Hay, and A. Restrepo, J. Clin. Microbiol. 35:3278-3283, 1997). This test has now been assessed as a means of following up PCM patients. A total of 24 PCM patients, classified according to their clinical presentation (6 with the acute form of the disease, of whom two had AIDS, 12 with the multifocal form of the disease, and 6 with the unifocal form of the disease), were studied. The four human immunodeficiency virus-negative patients with acute PCM showed a statistically significant decrease in circulating antigen levels after the start of antifungal therapy. Antigen levels in this group became negative by our criteria ( Collapse

Key Words Collapse

MESH Headings

• AIDS-Related Opportunistic Infections/diagnosis
• AIDS-Related Opportunistic Infections/drug therapy
• AIDS-Related Opportunistic Infections/microbiology
• Acute Disease
• Adolescent
• Adult
• Aged
• Antifungal Agents/therapeutic use
• Antigens, Fungal/blood
• Antigens, Fungal/chemistry
• Enzyme-Linked Immunosorbent Assay/methods
• Epitopes/blood
• Epitopes/chemistry
• Female
• Fungemia/diagnosis
• Fungemia/drug therapy
• Fungemia/microbiology
• Humans
• Male
• Middle Aged
• Molecular Weight
• Paracoccidioides/immunology
• Paracoccidioides/isolation & purification
• Paracoccidioidomycosis/diagnosis
• Paracoccidioidomycosis/drug therapy
• Paracoccidioidomycosis/microbiology
• Time Factors

Collapse

Grants Collapse

Affiliation(s)

B L Gómez Corporación para Investigaciones Biológicas, Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia
J I Figueroa
A J Hamilton
S Diez
M Rojas
A M Tobón
R J Hay
A Restrepo

Collapse

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.

Safety and efficacy of single-dose fluconazole compared with a 7-day regimen of itraconazole in the treatment of AIDS-related oropharyngeal candidiasis

The primary aim of this study was to compare the efficacy and safety of single-dose fluconazole and a 7-day regimen of itraconazole for the treatment of oropharyngeal candidiasis in human immunodeficiency virus (HIV)-positive patients. In this open-label trial, 40 HIV-positive patients with oropharyngeal candidiasis were randomized to receive either one dose of fluconazole 150 mg or seven daily doses of itraconazole 100 mg. Clinical condition was assessed at baseline, day 8, and day 30 (follow-up). In the fluconazole group, 15 of 20 (75%) patients were clinically cured on day 8, three (15%) were clinically improved, and two (10%) were treatment failures. At follow-up, six (30%) patients experienced relapse. In the itraconazole group, four of 17 (24%) patients were clinically cured at 8 days, and two (12%) were clinically improved; two patients relapsed by day 30. Ten (50%) patients in the itraconazole group were taking concomitant medications that could potentially affect the bioavailability of itraconazole. After excluding the results from these patients, clinical response rates remained significantly higher in the fluconazole treatment arm. These results suggest that a single 150-mg dose of fluconazole may be a safe, effective, and convenient therapy for acquired immune deficiency syndrome-related oropharyngeal candidiasis. The lower response rate in the patients who received itraconazole 100 mg daily for 7 days could be explained by drug interactions and the unpredictable absorption of itraconazole.

Clinically significant drug interactions in dermatology

Access to information on clinically significant drug interactions is not readily available. This can be a source of uncertainty, and locating this information can be tedious and time-consuming. The pharmacology of drug interactions is briefly discussed. The most common drug interactions involve altered hepatic metabolism. At least 26 drugs are such frequent offenders that they can be considered "red flag" drugs. In addition, an extensive list of current significant and less significant drug interactions of particular importance to the dermatologist is presented.

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.

Traditional management of onychomycosis

The traditional management of onychomycosis includes mechanical, chemical, and surgical approaches, as well as topical and oral antifungal medications. Topical preparations have been consistently disappointing, and the tendency in later years has been to rely on two systemic agents-griseofulvin and ketoconazole-for management of more severe or recalcitrant infections. However, both drugs require a long duration of therapy (4 to 6 months for fingernails, 10 to 18 months for toenails). Even with such prolonged treatment, the overall success rate is only about 15% to 30% for toenail infections and 50% to 70% for fingernail infections. Furthermore, both griseofulvin and ketoconazole have numerous potential side effects and drug/drug interactions. Therefore, laboratory monitoring should be performed during the course of treatment with these agents and they should be used only after evaluation of the patient's current medical status and a review of concomitant medications.

Pharmacoeconomic analysis of oral therapies for onychomycosis: a US model

An evaluation of treatment practices in 13 countries, not including the United States, has shown oral terbinafine to be more cost-effective (from a government payer perspective) than griseofulvin, itraconazole, and ketoconazole in the treatment of onychomycosis of toenails and fingernails. The purpose of this study was to evaluate the clinical and economic effects of oral griseofulvin, itraconazole, ketoconazole, and terbinafine in the treatment of onychomycosis from the perspective of a third-party payer in the United States. A previously constructed decision-analytic model evaluating the costs of onychomycosis in 13 countries outside the United States was updated to determine the costs of treating onychomycosis in the United States. Clinical management patterns were assessed to identify and quantify physician visits, laboratory tests, and adverse drug reaction treatment components for patients with toenail and fingernail onychomycosis. A random-effects model meta-analysis of treatment efficacy (mycologic cure) and New York Metropolitan Medicare charge data for physician fees were used in the treatment model. A sensitivity analysis assessing alternative dosing regimens and a rank order stability analysis investigating the effects of length of treatment, success rates, relapse rates, and drug acquisition costs on overall results were also conducted. Terbinafine had the lowest cost per mycologic cure after one treatment regimen for onychomycosis in both toenail and fingernail infections ($791.00 and $454.00, respectively). The costs of treating toenail and fingernail infections were comparatively higher for therapy with itraconazole ($1535.00 and $767.00, respectively), griseofulvin ($2385.00 and $837.00, respectively), and ketoconazole ($10,025.00 and $1512.00, respectively). As a primary treatment choice, terbinafine also had the lowest overall expected cost per patient for both toenail and fingernail infections ($977.00 and $550.00, respectively). Griseofulvin had expected costs ($1543.00 and $822.00, respectively) similar to itraconazole ($1588.00 and $894.00, respectively), whereas ketoconazole was the most expensive primary treatment choice ($2359.00 and $1287.00, respectively). This study demonstrates that terbinafine is an economical and cost-effective treatment for patients with dermatophytic onychomycosis, supporting European and Canadian studies. Except for the rank order of griseofulvin and itraconazole, sensitivity analyses show that these results are fairly stable.

Cutaneous mycoses in children

This article describes common cutaneous mycoses in children: mucocutaneous candidiasis, pityriasis versicolor, tinea corporis, tinea pedis, onychomycosis and tinea capitis. Topical therapy is effective in tinea corporis and pedis, pityriasis versicolor and cutaneous candidiasis. It is ineffective in tinea capitis, in immunocompromised children and onychomycosis. Griseofulvin has been the main treatment until now in children, but it is only fungistatic, may cause interactions and has to be given for long periods. Ketoconazole has not been widely accepted for use in children because of hepatotoxicity and it is not an effective as griseofulvin. There are few data on paediatric use of fluconazole, although it is available in liquid form, has an excellent safety profile and may become important for treating paediatric mycoses. Similarly, there are only limited data on itraconazole in this area, with most experience in tinea capitis. There is only a 100-mg capsule available, which is not easy to administer in paediatric dosages. All azoles have the potential for drug interaction. Most experience in the treatment of children with the allylamine, terbinafine, has been in tinea capitis. A treatment time of 4 weeks with terbinafine and 8 weeks with griseofulvin has produced similar results at 12 weeks. There are also limited data on the use of terbinafine in paediatric onychomycosis. Terbinafine has the best safety profile, least risk of drug interactions and may be the most suitable alternative to griseofulvin in children. The lack of a liquid formulation may preclude its use. Itraconazole and fluconazole are also potential replacement drugs for griseofulvin.