Ketoconazole in the treatment of paracoccidioidomycosis and histoplasmosis

Overview of Antifungal Drugs against Paracoccidioidomycosis: How Do We Start, Where Are We, and Where Are We Going?

Paracoccidioidomycosis is a neglected disease that causes economic and social impacts, mainly affecting people of certain social segments, such as rural workers. The limitations of antifungals, such as toxicity, drug interactions, restricted routes of administration, and the reduced bioavailability in target tissues, have become evident in clinical settings. These factors, added to the fact that Paracoccidioidomycosis (PCM) therapy is a long process, lasting from months to years, emphasize the need for the research and development of new molecules. Researchers have concentrated efforts on the identification of new compounds using numerous tools and targeting important proteins from Paracoccidioides, with the emphasis on enzymatic pathways absent in humans. This review aims to discuss the aspects related to the identification of compounds, methodologies, and perspectives when proposing new antifungal agents against PCM.

Chronic progressive pulmonary paracoccidioidomycosis in a female immigrant from Venezuela

Paracoccidioidomycosis (PCM) is a fungal infection caused by Paracoccidioides brasiliensis and P. lutzii. It is endemic to South and Central America. While PCM frequently remains latent, the disease can reactivate years after the initial infection. As the disease is rare outside the endemic area, and symptoms can mimic other pulmonary diseases, correct diagnosis can be challenging for clinicians in developed countries. In this report, we present the case of a 57-year-old female Venezuelan immigrant with PCM. She was initially misdiagnosed with sarcoidosis and treated with corticosteroids, leading to an exacerbation of the infection requiring intensive care. Because cultivation of Paracoccidioides sp. is slow and unsensitive, we opted for microscopic observation of fungal elements and molecular testing on a tissue biopsy and bronchoalveolar lavage (BAL) together with antibody detection. This allowed the diagnosis of PCM, enabling specific management. PCM and other imported mycoses should be considered as a differential diagnosis in patients originating from South and Central America displaying symptoms suggestive of sarcoidosis. The reviews of this paper are available via the supplemental material section.

EPIDEMIOLOGY OF PARACOCCIDIOIDOMYCOSIS

The epidemiological characteristics of paracoccidioidomycosis were reviewed and updated. The new endemic areas in Brazil were discussed in the section regarding the geographic distribution of the mycosis. Subclinical infection with Paracoccidioides brasiliensis was discussed on the basis of skin test surveys with antigens of the fungus, seroepidemiological studies, and disease cases outside Latin America. Large case series permitted a comparison of the prevalence of the mycosis in different regions, its estimated incidence and risk factors for the development of the disease. Aspects modulating the expression of the clinical forms of paracoccidioidomycosis are also presented. This review also deals with diseases associated with the mycosis, opportunistic paracoccidioidomycosis, lethality, mortality and infection and disease in animals.

Drug safety assessment of oral formulations of ketoconazole

INTRODUCTION

Ketoconazole was the first broad-spectrum oral antifungal approved by the FDA in 1981. Post-marketing reports of drug-related hepatotoxicity, endocrine dysregulation and drug interactions resulted in market withdrawal of the drug in some countries and strict product relabeling in others.

AREAS COVERED

This drug safety review summarizes reports of oral ketoconazole-related adverse events retrieved from a search of the PubMed database using the search strategy 'ketoconazole OR Nizoral AND hepat*', references from relevant publications, and data from the FDA Adverse Event Reporting System.

EXPERT OPINION

Although oral ketoconazole is effective in treating fungal infections, the potential for drug interactions, endocrine dysregulation, and hepatotoxicity may outweigh its benefits. Newer oral antifungals have similar or greater efficacy in treating dermatologic conditions and are associated with less risk. Likewise, newer agents with specific targets and fewer drug interactions have been developed to treat systemic fungal infections. Therefore, by the time ketoconazole prescribing guidelines were amended, its use had already largely been replaced with newer antifungals. Being that ketoconazole was the first broad-spectrum oral antifungal, experience with the drug made patient safety, and especially hepatic safety, an important consideration in future antifungal development.

Drugs for treating paracoccidioidomycosis

BACKGROUND

Paracoccidioidomycosis is a fungal infection found in particular geographic localities in Latin America. Treatment can last for up to two years is often associated with complications, including relapse, but people may die without it.

OBJECTIVES

To evaluate drugs used for treating paracoccidioidomycosis.

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group Specialized Register (January 2006), CENTRAL (The Cochrane Library 2005, Issue 4), PubMed (1966 to January 2006), EMBASE (1974 to January 2006), LILACS (1982 to January 2006), conference proceedings, and reference lists. We also contacted researchers and pharmaceutical companies.

SELECTION CRITERIA

Randomized controlled trials comparing drugs for treating people with paracoccidioidomycosis.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial eligibility and methodological quality, and extracted data, including adverse events.

MAIN RESULTS

One trial with 42 participants met the inclusion criteria that compared imidazoles (itraconazole and ketoconazole) with sulfadiazine. No difference was detected for cure or clinical improvement, or serological titres after 10 months of treatment, and there was no difference detected in adverse events.

AUTHORS' CONCLUSIONS

The small number of participants and the short follow-up period impede definitive conclusions.

Antifungal agents. Part II. The azoles

Before 1978, amphotericin B and flucytosine were the only drugs available for the treatment of systemic fungal infections. The imidazoles, miconazole and ketoconazole, were introduced during the next 3 years. Intravenously administered miconazole served a limited therapeutic role and is no longer available. Orally administered ketoconazole, an inexpensive, effective, and convenient option for treating mucosal candidiasis, was widely used for a decade because it was the only available oral therapy for systemic fungal infections. During the 1990s, use of ketoconazole diminished because of the release of the triazoles--fluconazole and itraconazole. Fluconazole is less toxic and has several pharmacologic advantages over ketoconazole, including penetration into the cerebrospinal fluid. In addition, it has superior efficacy against systemic candidiasis, cryptococcosis, and coccidioidomycosis. Despite a myriad of drug interactions and less favorable pharmacologic and toxicity profiles in comparison with fluconazole, itraconazole has become a valuable addition to the antifungal armamentarium. It has excellent activity against sporotrichosis and seems promising in the treatment of aspergillosis. Itraconazole has replaced ketoconazole as the therapy of choice for nonmeningeal, non-life-threatening cases of histoplasmosis, blastomycosis, and paracoccidioidomycosis and is effective in patients with cryptococcosis and coccidioidomycosis, including those with meningitis. Further investigation into the development of new antifungal agents is ongoing.

Itraconazole for the treatment of histoplasmosis in cats

Eight cats with histoplasmosis were treated with itraconazole at 5 mg/kg per dose PO bid. There were multiple sites of infection, and 2 of the cats had hypercalcemia that was attributed to the histoplasmosis. All 8 cats were eventually cured, but 2 cats experienced recurrences of disease after completion of therapy, requiring 2 to 3 additional months of itraconazole. There were no clinically relevant adverse effects during treatment. Although a limited number of cats were treated, the study suggests that itraconazole is a well-tolerated and effective drug for the treatment of histoplasmosis in the cat.

Oral azole drugs as systemic antifungal therapy

The oral azole drugs--ketoconazole, fluconazole, and itraconazole--represent a major advance in systemic antifungal therapy. Among the three, fluconazole has the most attractive pharmacologic profile, including the capacity to produce high concentrations of active drug in cerebrospinal fluid and urine. Ketoconazole, the first oral azole to be introduced, is less well tolerated than either fluconazole or itraconazole and is associated with more clinically important toxic effects, including hepatitis and inhibition of steroid hormone synthesis. However, ketoconazole is less expensive than fluconazole and itraconazole--an especially important consideration for patients receiving long-term therapy. All three drugs are effective alternatives to amphotericin B and flucytosine as therapy for selected systemic mycoses. Ketoconazole and itraconazole are effective in patients with the chronic, indolent forms of the endemic mycoses, including blastomycosis, coccidioidomycosis, and histoplasmosis; itraconazole is also effective in patients with sporotrichosis. Fluconazole is useful in the common forms of fungal meningitis--namely, coccidioidal and cryptococcal meningitis. In addition, fluconazole is effective for selected patients with serious candida syndromes such as candidemia, and itraconazole is the most effective of the azoles for the treatment of aspergillosis.

Antifungal agents used for deep-seated mycotic infections

The increased use of immunosuppressive regimens in organ transplantation and in the treatment of malignant lesions and the epidemic of acquired immunodeficiency syndrome (AIDS) are major reasons for the greater prevalence of fungal infections seen in clinical practice during the past decade. The traditional cornerstone of antifungal treatment, amphotericin B, continues to play a major role in deep-seated mycotic infections. The indications for intravenously administered miconazole have become limited. Orally administered flucytosine remains useful in certain infections, particularly cryptococcal meningitis. The new orally administered antifungal agents ketoconazole and fluconazole have been approved for clinical use and have supplanted amphotericin B in certain situations. Investigational antifungal agents, including liposomal amphotericin B, itraconazole, and saperconazole, hold promise for the future. Active investigation in the development of new antifungal agents is expected to continue.

Treatment of paracoccidioidomycosis with itraconazole

Forty-seven patients with active paracoccidioidomycosis were treated with itraconazole. The majority of the patients (45) had the chronic adult form of the disease while the remaining exhibited the juvenile form. All of the patients received itraconazole, 100 mg day-1, with the exception of two for whom the clinical condition necessitated a larger dose. The mean duration of therapy was 6 months, with a range of 3-24 months. Clinically, the skin and mucous membrane lesions as well as abdominal pain, auscultatory alterations and dysphonia improved markedly during treatment with a concomitant increase in weight. However, other symptoms (cough, expectoration and dyspnoea) persisted as sequelae in some cases. As expected adrenal insufficiency also persisted. The radiological lesions showed a gradual decrease of both scattered and confluent infiltrates, present in 67% of patients before, and in 13% at the end of treatment. On the other hand, fibrosis became more evident at the termination of therapy, increasing from 62% of patients at the beginning of therapy to 81% at the end. The mycological tests (direct examination and cultures) became negative during the first month of treatment in 42 patients (87%). A decline in specific antibody titres was observed in 72% of patients by the end of treatment. Evaluation of therapy by means of a scoring system indicated complete resolution of the disease in one patient (2%), marked improvement in 42 (89%) and minor improvement in four (8.5%); none of the patients showed a deterioration of their disease during therapy. Of fifteen patients who were followed up for 12 months post-therapy none showed clinical relapse during this period. The results of this study confirm the efficacy of itraconazole in the treatment of paracoccidioidomycosis.

Histoplasmosis presenting as hyperplastic gingival lesion

A case of histoplasmosis presenting as ulcerated, hyperplastic gingiva and with no other systematic signs and symptoms is reported. The clinical presentation and the rarity of this condition led one of us to the differential diagnosis of a malignant lesion. The correct diagnosis was made after histological examination and tissue culture which yielded Histoplasma capsulatum. The patient was successfully treated with ketoconazole.

Treatment of disseminated histoplasmosis in hamsters

A comparative study between itraconazole, ketoconazole and amphotericin B in the treatment of experimental histoplasmosis in hamsters was carried out. Seventy five animals were inoculated intracardiacally with the yeast-phase of Histoplasma capsulatum. They were divided in 5 groups: 1) treated with itraconazole by gavage (g) at a daily dose of 16 mg/kg; 2) treated with ketoconazole by (g) at a daily dose of 80 mg/kg; 3) treated with amphotericin B intraperitoneally (i.p.) at 6 mg/kg every other day; 4) control animals receiving distilled water i.p. and 5) control animals receiving P.E.G. 200 by (g). All the treatments were started one week after the challenge inoculation and they were given for 21 days. The results were evaluated by autopsy of all the animals one week after the end of the treatments. The following determinations were taken into account: microscopic examinations of spleen, liver and lungs and cultures of the spleen with determination of colony forming units/g. All the antifungal drugs used in this study were able to cause negative microscopic examinations of the liver, spleen and lungs; but only amphotericin B produced culture negative results. Itraconazole and ketoconazole presented 66% and 86% of positive cultures respectively, nevertheless the C.F.U. were lower than those obtained in control groups. In these experimental conditions amphotericin B seems to be more active than the azolic compounds and itraconazole is slightly superior to ketoconazole at a lower dose.

Chronic pulmonary histoplasmosis with an oral lesion

Histoplasmosis is a fungal disease resulting from inhalation of airborne spores of the organism Histoplasma capsulatum. The disease is endemic to the Ohio and Mississippi river valleys. Oral lesions are not common, but when present, they are usually associated with the severe disseminated form of histoplasmosis. This particular case is presented as an example of chronic pulmonary histoplasmosis in which a localized gingival lesion represented the initial clinical manifestation of the disease. Diagnosis was based on a positive biopsy and the results of chest radiographic examination. If, as in this case, serologic, hematologic, and physical examination results are negative, the biopsy of suspicious lesions is of paramount importance to the clinical differential diagnosis.

Antifungal agents used for deep-seated mycotic infections

The main antifungal agents used for deep-seated mycotic infections are the broad-spectrum antifungal drug amphotericin B, the narrow-spectrum agent flucytosine, and the newer broad-spectrum agents ketoconazole, miconazole, and itraconazole. Amphotericin B remains the cornerstone of antifungal therapy. For the treatment of cryptococcal meningitis, the current recommendation is for the combined use of amphotericin B and flucytosine. Published clinical experience with the newer agents is limited. Not all patients from whom fungal agents have been isolated require treatment; the extent of the fungal infection should be determined, when possible, for evaluation of the need for treatment.

Ketoconazole in the treatment of experimental murine paracoccidioidomycosis

In a murine model of chronic disseminated paracoccidioidomycosis (strain 18; intravenous route), Ketoconazole (200 mg/kg in 0.2% agar) was given daily by gavage in three different schedules. Continuous treatment from an early stage of infection (day 3) up to week 20 was the most effective protocol, leading to remission of histopathological lesions and of both humoral and cellular anti-P. brasiliensis immune response, and clearance of the fungus in lungs; only 1 treated animal at week 20 showed pulmonary granulomas, although less extensive than control mice. Continuous treatment from early stage up to week 8, followed by a 16 week-period of drug discontinuity, caused remission of lesions in all but 3 treated mice which showed active pulmonary paracoccidioidomycosis similar to controls (14.2% of unresponsiveness to treatment). The continuous Ketoconazole protocol since a late stage of infection (week 4) up to week 20 produced a slower remission of lesions and immune response when compared with the first drug schedule. In this model of paracoccidioidomycosis, Ketoconazole showed no detectable side-effects and was a very effective drug especially in a prolonged administration protocol from an early stage of infection.

Comparative efficacy of ketoconazole and mebendazole in experimental trichinosis

The therapeutic efficacy of ketoconazole and mebendazole was studied in ICR/CD-1 mice infected with Trichinella spiralis for 17 to 20 weeks. Efficacy of both drugs was over 70% when compared with results in control mice. This study indicates that both ketoconazole and mebendazole should be considered in the treatment of trichinosis in humans.

Paracoccidioidomycosis: a comparative study of the evolutionary serologic, clinical and radiologic results for patients treated with ketoconazole or amphotericin B plus sulfonamides

A comparative study of two groups of patients with paracoccidioidomycosis was carried out with the objective of comparing the evolutionary serologic, clinical and radiologic results after 6, 12, 15 and 18 months of treatment with ketoconazole (22 patients) or amphotericin B plus sulfonamides (32 patients). The serologic data analyzed as a whole showed a tendency to sharper drops in antibody titers in the patients treated with ketoconazole. Clinically patients treated with ketoconazole fared better but the differences were not statistically significant. No statistical difference was detected between groups in terms of the results of radiologic evolution.

Ketoconazole. Mechanism of action, spectrum of activity, pharmacokinetics, drug interactions, adverse reactions and therapeutic use

Ketoconazole is a well-tolerated oral antifungal agent with a broad spectrum of activity in vitro, but in vitro testing has not yet been correlated to in vivo results. In addition, many variables that can alter in vitro test results have been identified. The drug shows effectiveness in the treatment of paracoccidioidomycosis, chronic mucocutaneous candidiasis, oral thrush, coccidioidomycosis and histoplasmosis. It was recently approved for use in blastomycosis. It is not yet approved for use in dermatophyte infections, but a large body of literature exists supporting this application. Ketoconazole has several reported drug interactions, including lower bioavailability with cimetidine, accumulation of cyclosporin during concurrent therapy and a possible disulfiram-like reaction with alcohol. It is highly protein bound to albumin and is extensively metabolized. Dosage adjustment is not required in renal failure. The main side effects are gastrointestinal and occur in 5-10% of the patients. Rare side effects include gynecomastia and hepatotoxicity. The latter is reported to occur in 1 of 12,000 patients. Ketoconazole impairs testosterone synthesis, and therefore it is recommended that administration more than once daily be avoided in men. The usual dosage is 200-400 mg administered once daily. Few comparative or controlled studies have been published thus far. How it compares to amphotericin B is not known. The optimum dosage and the optimum duration of therapy are not established.

Ketoconazole: an orally effective antifungal agent. Mechanism of action, pharmacology, clinical efficacy and adverse effects

Ketoconazole is a new, orally effective, antifungal agent. It is an imidazole compound and like other antifungals of this group, has a wide spectrum of use. Effectiveness has been shown in a variety of deep fungal infections as well as in superficial infections such as candidiasis, dermatophytosis and tinea versicolor. Although it first appeared to be a remarkably safe agent associated with only minor side effects, with more use it has become apparent that symptomatic drug-induced hepatitis occurs in approximately 1 in 12,000 patients. This idiosyncratic side effect and potential effects on testosterone and cortisol synthesis may limit the use of ketoconazole to deep fungal infections and severe recalcitrant superficial infections of the skin.

A method for the determination of drug effectiveness in onychomycosis. Trials with ketoconazole and griseofulvin ultramicrosize

A new method for assessing drug effectiveness in onychomycosis is presented. It is based on the clinical experience when three systemic antifungal drugs (griseofulvin, thiabendazole, and ketoconazole) are used against onychomycosis. These drugs act clinically as a barrier to the invasion of the fungus toward the proximal areas of the nail plate. A monthly quantity of normal nail plate should be produced by a given subject after the administration of an effective dose of the antifungal being tested. This quantity is best measured at monthly intervals, and this in fact reflects the normal monthly nail plate growth for the individual. Although there is a slight variation among individuals, most normal healthy subjects grow 1.5 to 2 mm of nail plate per month from their large toenails and 3 to 4 mm of nail plate per month from their fingernails. Utilizing this quantitative system, ketoconazole and griseofulvin ultramicrosize were compared in the treatment of distal subungual onychomycosis by Trichophyton rubrum. In a double-blind study, sixteen patients were treated. It appears that both griseofulvin and ketoconazole can eradicate the episode of onychomycosis. One-year use of a topical antifungal cream after clinical cure of onychomycosis prevented reinfection in the 12-month follow-up period. The use of ketoconazole in long-term therapy may result in serious side effects and should be considered carefully prior to treatment.

Ketoconazole

The treatment of most fungal infections is difficult, at best. Antifungal therapy is complicated by the development of resistant organisms and by the toxicity of many agents. Ketoconazole, an orally active imidazole derivative, has been approved by the Food and Drug Administration for the treatment of candidiasis, chronic mucocutaneous candidiasis, oral thrush, candiduria, coccidioidomycosis, histoplasmosis, chromomycosis, and paracoccidioidomycosis. At present, there is very little peer review literature on ketoconazole's effectiveness for several of its approved indications. Gastrointestinal side effects account for the majority of reported adverse reactions; however, preliminary evidence suggests that higher dosages of ketoconazole may decrease adrenal steroidogenesis. Currently, ketoconazole 200-400 mg/d is recommended; the duration of therapy remains to be firmly established. Until well-designed clinical trials are completed and ketoconazole's effectiveness is compared to that of established antifungal agents, its use should be limited.

Antifungal chemotherapy

When the decision to treat a fungal infection is made, there are several antifungal agents available for use. AmB remains the first-line drug in the treatment of most systemic fungal infections. Miconazole should be used to treat patients who cannot tolerate AmB or who are infected with AmB-resistant organisms. Ketoconazole has a distinct advantage in that it is a relatively nontoxic oral agent and may prove very effective in treating non-life-threatening chronic fungal infections. Clinical experience with miconazole and ketoconazole is too limited at present to recommend them as first-line therapeutic agents, except in a limited number of clinical situations. 5-FC should only be used in combination with AmB to treat yeast infections.

Treatment of paracoccidioidomycosis with ketoconazole: a three-year experience

The results of ketoconazole therapy in 38 patients with active paracoccidioidomycosis are described. Treatment consisted of a 200 mg tablet a day for 6 months. Evaluation was accomplished by means of a scoring system and the results were as follows: none of the patients worsened during therapy, one was found to be unchanged, five had minor improvement, 330 had major improvement, and there was complete resolution of the pretherapy conditions in 13. These findings plus the lack of toxicity of the drug and the facility for oral administration, make of ketoconazole a first line drug for the treatment of paracoccidioidomycosis.

Post-therapy status of paracoccidioidomycosis treated with ketoconazole

Twenty-four paracoccidioidomycosis patients who completed a course of therapy with ketoconazole were followed for 12 months after treatment, and 10 of these patients were followed for 24 months. Only two of these patients relapsed; the remaining continued in remission. There were no fatalities. Immunologic tests showed decreased antibody activity and increased skin test reactivity to paracoccidioidin in comparison with the results obtained at the end of therapy. These findings indicate that ketoconazole therapy has improved the prognosis of patients with paracoccidioidomycosis.

Current management of fungal enteritis

Fungal infections of the gastrointestinal tract have risen to higher levels of prevalence in the past decade. Major factors accounting for this increase are social changes, such as the increased ease and frequency of travel, which exposes the individual to environmental conditions that may result in fungal infection; increasing use of antibiotic and hormonal medications by otherwise healthy persons; and improved therapy for other diseases, such as polychemotherapy of cancer with its immunosuppressive effects. Both noninvasive and invasive fungal disease of the intestinal tract in otherwise healthy individuals can be successfully treated. The invasive fungal infections in patients with severe prior underlying disease are often first diagnosed postmortem, but improvement in serologic techniques now offers a possibility of earlier diagnosis and therapeutic intervention.