Skin concentrations and pharmacokinetics of posaconazole after oral administration

Safety and efficacy of new generation azole antifungals in the management of recalcitrant superficial fungal infections and onychomycosis

INTRODUCTION

Terbinafine is considered the gold standard for treating skin fungal infections and onychomycosis. However, recent reports suggest that dermatophytes are developing resistance to terbinafine and the other traditional antifungal agents, itraconazole and fluconazole. When there is resistance to terbinafine, itraconazole or fluconazole, or when these agents cannot used, for example, due to potential drug interactions with the patient's current medications, clinicians may need to consider off-label use of new generation azoles, such as voriconazole, posaconazole, fosravuconazole, or oteseconazole. It is essential to emphasize that we do not advocate the use of newer generation azoles unless traditional agents such as terbinafine, itraconazole, or fluconazole have been thoroughly evaluated as first-line therapies.

AREAS COVERED

This article reviews the clinical evidence, safety, dosage regimens, pharmacokinetics, and management algorithm of new-generation azole antifungals.

EXPERT OPINION

Antifungal stewardship should be the top priority when prescribing new-generation azoles. First-line antifungal therapy is terbinafine and itraconazole. Fluconazole is a consideration but is generally less effective and its use may be off-label in many countries. For difficult-to-treat skin fungal infections and onychomycosis, that have failed terbinafine, itraconazole and fluconazole, we propose consideration of off-label voriconazole or posaconazole.

Challenges towards management of CARD9-deficient patients with phaeohyphomycosis: A case report and case series study

BACKGROUND

A number of recalcitrant phaeohyphomycosis cases with a life-threatening prognosis have been observed in CARD9-deficient patients, but little is known about the long-term management strategies that are effective for such intractable individuals.

OBJECTIVES

To study the genetic and immunological mechanisms underlying recalcitrant phaeohyphomycosis and to share our clinical experiences regarding its treatment.

PATIENTS/METHODS

Ten CARD9-deficient patients with recalcitrant phaeohyphomycosis admitted to our centre in the past two decades were followed-up, and their clinical presentations, laboratory findings, treatment and prognoses were analysed; one of them was a novel case of recalcitrant phaeohyphomycosis harbouring CARD9 mutations. Innate and adaptive immunological responses of patient-derived peripheral blood mononuclear cells were evaluated using ELISA and flow cytometry.

RESULTS

We identified a total of seven CARD9 mutations in the ten analysed patients. Moreover, patient-derived cells exhibited a significant impairment of innate and adaptive immune responses upon fungus-specific stimulation. All the patients experienced recurrence and exacerbation; four of them died, two exhibited continued disease progress with unsatisfactory therapeutic efficacy, three showed obvious improvement under maintenance therapy, and only one achieved a clinical cure.

CONCLUSIONS

Our study highlighted that otherwise healthy patients diagnosed with early-onset, unexplained and recalcitrant phaeohyphomycosis should be analysed for CARD9 mutations and immune deficiency. Thereafter, the length and choice of management remain challengeable and must be adjusted based on the clinical presentations and responses of patients over their lifetimes. Although continued posaconazole treatment may be the promising first-line therapy at present, novel strategies are worth exploring.

Review of the alternative therapies for onychomycosis and superficial fungal infections: posaconazole, fosravuconazole, voriconazole, oteseconazole

Terbinafine and itraconazole are the most commonly used oral antifungals to treat onychomycosis and superficial dermatomycoses. Recently, poor response to oral terbinafine has been reported. We have summarized the most appropriate dosing regimens of posaconazole, fosravuconazole, voriconazole, and oteseconazole (VT-1161) to treat onychomycosis and superficial fungal infections. A structured search on PubMed and Google Scholar was conducted. Additionally, the bibliographies of selected articles were searched to identify relevant records. The number of records identified from the searches was 463, with 50 articles meeting the inclusion criteria for review. None of the new azoles are US FDA approved for onychomycosis treatment; however, an increasing number of studies have evaluated these agents. The efficacies (complete cure and mycologic cure) of the antifungal agents for dermatophyte great toenail onychomycosis treatment are terbinafine 250 mg/day × 12 weeks (Phase III trial) (38%, 70%), itraconazole 200 mg/day × 12 weeks (Phase III trial) (14%, 54%), posaconazole 200 mg/day × 24 weeks (Phase IIB) (54.1%, 70.3%), fosravuconazole 100 mg/day ravuconazole equivalent × 12 weeks (Phase III) (59.4%, 82.0%), and oteseconazole 300 mg/day loading dose × 2 weeks (Phase II), followed by 300 mg/week × 10 weeks (maintenance dose) (45%, 70%). Guidelines for monitoring are also presented.

Potency and preclinical evidence of synergy of oral azole drugs and miltefosine in an ex vivo model of Leishmania (Viannia) panamensis infection

Failure of treatment of cutaneous leishmaniasis with antimonial drugs and miltefosine is frequent. Use of oral combination therapy represents an attractive strategy to increase efficacy of treatment and reduce the risk of drug resistance. We evaluated the potency of posaconazole, itraconazole, voriconazole and fluconazole, and the potential synergy of those demonstrating the highest potency, in combination with miltefosine (HePC), against infection with Leishmania (Viannia) panamensis. Synergistic activity was determined by isobolograms and calculation of Fractional Inhibitory Concentration Index (FICI), based on parasite quantification using an ex vivo model of human PBMCs infected with a luciferase-transfected, antimony and miltefosine sensitive line of L. panamensis. The drug combination and concentrations that displayed synergy were then evaluated for anti-leishmanial effect in 10 clinical strains of L. panamensis by qRT-PCR of Leishmania 7SLRNA. High potency was substantiated for posaconazole and itraconazole against sensitive as well as HePC and antimony resistant lines of L. panamensis, whereas fluconazole and voriconazole displayed low potency. HePC combined with posaconazole (Poz) demonstrated evidence of synergy at free drug concentrations achieved in plasma during treatment (2 μM HePC + 4 μM Poz). FICI, based on 70% and 90% reduction of infection, was 0.5 for the sensitive line. Combination of 2 μM HePC + 4 μM Poz effected significantly greater reduction of infection by clinical strains of L. panamensis than individual drugs. Orally administrable miltefosine/posaconazole combinations demonstrated synergistic anti-leishmanial capacity ex vivo against L. panamensis, supporting their potential as a novel therapeutic strategy to improve efficacy, and effectiveness of treatment.

Race reporting and representation in onychomycosis clinical trials: A systematic review

BACKGROUND

Onychomycosis is the most common nail disease seen in clinical practice. Inclusion of diverse groups in onychomycosis clinical trials subjects is necessary to generalise efficacy data.

OBJECTIVES

We aimed to systematically review race and ethnicity reporting and representation, as well as, treatment outcomes in onychomycosis clinical trials.

METHODS

A PubMed search for onychomycosis clinical trials was performed in August 2020. Primary clinical trial data were included and post hoc analyses were excluded. Categorical variables were compared using chi-squared and Fisher's exact tests. Statistical significance was set at p < .05. Photos in articles were categorised by Fitzpatrick skin type.

RESULTS

Only 32/182 (17.5%) trials reported on race and/or ethnicity and only one trial compared treatment efficacy in different subgroups. Darker skin colours were infrequently depicted in articles. Topical treatment, location with ≥1 US-based site, industry funding type and publication date after 2000 were significantly associated with reporting of racial/ethnic data (p < .05 for all comparisons).

LIMITATIONS

Demographics on excluded subjects and methods of recruitment were not available. Assigning Fitzpatrick skin type is inherently subjective.

CONCLUSIONS

This study highlights a need for consistent reporting of races and ethnicities of onychomycosis clinical trial participants with subgroup analyses of treatment efficacies.

Pharmacokinetics and Pharmacodynamics of Posaconazole

Posaconazole is typically used for preventing invasive yeast and mold infections such as invasive aspergillosis in high-risk immunocompromised patients. The oral suspension was the first released formulation and many pharmacokinetic and pharmacodynamic studies of this formulation have been published. Erratic absorption profiles associated with this formulation were widely reported. Posaconazole exposure was found to be significantly influenced by food and many gastrointestinal conditions, including pH and motility. As a result, low posaconazole plasma concentrations were obtained in large groups of patients. These issues of erratic absorption urged the development of the subsequently marketed delayed-release tablet, which proved to be associated with higher and more stable exposure profiles. Shortly thereafter, an intravenous formulation was released for patients who are not able to take oral formulations. Both new formulations require a loading dose on day 1 to achieve high posaconazole concentrations more quickly, which was not possible with the oral suspension. So far, there appears to be no evidence of increased toxicity correlated to the higher posaconazole exposure achieved with the regimen for these formulations. The higher systemic availability of posaconazole for the delayed-release tablet and intravenous formulation have resulted in these two formulations being preferable for both prophylaxis and treatment of invasive fungal disease. This review aimed to integrate the current knowledge on posaconazole pharmacokinetics, pharmacodynamics, major toxicity, existing resistance, clinical experience in special populations, and new therapeutic strategies in order to get a clear understanding of the clinical use of this drug.

Blood and tissue distribution of posaconazole in a rat model of invasive pulmonary aspergillosis

Posaconazole is the recommended prophylactic agent in patients at high risk of invasive fungal infection, since adequate drug levels seem to be reached in target sites despite the relatively low levels detected in blood. The objective of this study is to obtain pharmacokinetic (PK) information associated to blood and tissue distribution of posaconazole in an animal model of invasive pulmonary aspergillosis. The PK parameters in lung samples were systematically higher than in serum. After multiple-dose administration of posaconazole, a significant accumulation of the drug was evident in lung tissue. The PK behavior of posaconazole in this particular experimental model is similar to that observed in humans. Thus, we believe this model could be a valid tool to evaluate posaconazole exposure-response relationship.

Pharmacokinetics of Posaconazole Oral Suspension in Children Dosed According to Body Surface Area

BACKGROUND

Antifungal prophylaxis remains challenging in immunocompromised children as no clear consensus has yet been reached about which drug to be used. Posaconazole has a broad spectrum of activity, a favorable safety profile and excellent prophylactic activity in adults. However, a lack of pharmacokinetic studies in pediatric patients hampers routine implementation. This study investigates the pharmacokinetics of a newly introduced posaconazole dosing regimen based on the body surface area in pediatric hematologic patients.

METHODS

In this prospective pharmacokinetic study, 8 blood samples were taken during 1 dosing interval at steady state in children aged 13 years or younger with hematologic malignancy, who were treated prophylactically with posaconazole oral suspension at a dose of 120 mg/m 3 times daily. Posaconazole plasma concentrations were determined using high-performance liquid chromatography fluorescence detection.

RESULTS

One hundred twelve samples were taken from 14 patients with a mean age of 6.7 ± 2.8 years. A median posaconazole daily dose of 100.0 mg (77.3-100.0) 3 times daily (tid), corresponding to a median of 117.9 mg/m (112.2-120.4) tid, resulted in mean trough posaconazole plasma concentrations of 0.85 ± 0.56 mg/L. Pharmacokinetic analysis revealed a clearance of 0.8 L/(h kg) (0.5-1.4). No invasive fungal infections or adverse events were encountered during treatment.

CONCLUSIONS

Posaconazole is a promising antifungal agent to be used prophylactically in hematologic patients aged 13 years or younger. Administering posaconazole oral suspension in a dosage of 120 mg/m tid results in adequate posaconazole plasma exposure, without significant adverse events.

Severe Dermatophytosis and Acquired or Innate Immunodeficiency: A Review

Dermatophytes are keratinophilic fungi responsible for benign and common forms of infection worldwide. However, they can lead to rare and severe diseases in immunocompromised patients. Severe forms include extensive and/or invasive dermatophytosis, i.e., deep dermatophytosis and Majocchi’s granuloma. They are reported in immunocompromised hosts with primary (autosomal recessive CARD9 deficiency) or acquired (solid organ transplantation, autoimmune diseases requiring immunosuppressive treatments, HIV infection) immunodeficiencies. The clinical manifestations of the infection are not specific. Lymph node and organ involvement may also occur. Diagnosis requires both mycological and histological findings. There is no consensus on treatment. Systemic antifungal agents such as terbinafine and azoles (itraconazole or posaconazole) are effective. However, long-term outcome and treatment management depend on the site and extent of the infection and the nature of the underlying immunodeficiency.

An unusual ulcer: A case of cutaneous mucormycosis caused by Rhizopus oryzae

Mucormycoses are high-mortality infections feared by clinicians worldwide. They predominantly affect immunocompromised hosts and are associated with a spectrum of disease. We describe a case of cutaneous mucormycosis caused by Rhizopus oryzae in a patient with multiple risk factors cured with complete surgical excision and a short course of antifungal therapy.

Phase II metabolism in human skin: skin explants show full coverage for glucuronidation, sulfation, N-acetylation, catechol methylation, and glutathione conjugation

Although skin is the largest organ of the human body, cutaneous drug metabolism is often overlooked, and existing experimental models are insufficiently validated. This proof-of-concept study investigated phase II biotransformation of 11 test substrates in fresh full-thickness human skin explants, a model containing all skin cell types. Results show that skin explants have significant capacity for glucuronidation, sulfation, N-acetylation, catechol methylation, and glutathione conjugation. Novel skin metabolites were identified, including acyl glucuronides of indomethacin and diclofenac, glucuronides of 17β-estradiol, N-acetylprocainamide, and methoxy derivatives of 4-nitrocatechol and 2,3-dihydroxynaphthalene. Measured activities for 10 μM substrate incubations spanned a 1000-fold: from the highest 4.758 pmol·mg skin(-1)·h(-1) for p-toluidine N-acetylation to the lowest 0.006 pmol·mg skin(-1)·h(-1) for 17β-estradiol 17-glucuronidation. Interindividual variability was 1.4- to 13.0-fold, the highest being 4-methylumbelliferone and diclofenac glucuronidation. Reaction rates were generally linear up to 4 hours, although 24-hour incubations enabled detection of metabolites in trace amounts. All reactions were unaffected by the inclusion of cosubstrates, and freezing of the fresh skin led to loss of glucuronidation activity. The predicted whole-skin intrinsic metabolic clearances were significantly lower compared with corresponding whole-liver intrinsic clearances, suggesting a relatively limited contribution of the skin to the body's total systemic phase II enzyme-mediated metabolic clearance. Nevertheless, the fresh full-thickness skin explants represent a suitable model to study cutaneous phase II metabolism not only in drug elimination but also in toxicity, as formation of acyl glucuronides and sulfate conjugates could play a role in skin adverse reactions.

Tissue penetration of antifungal agents

Understanding the tissue penetration of systemically administered antifungal agents is critical for a proper appreciation of their antifungal efficacy in animals and humans. Both the time course of an antifungal drug and its absolute concentrations within tissues may differ significantly from those observed in the bloodstream. In addition, tissue concentrations must also be interpreted within the context of the pathogenesis of the various invasive fungal infections, which differ significantly. There are major technical obstacles to the estimation of concentrations of antifungal agents in various tissue subcompartments, yet these agents, even those within the same class, may exhibit markedly different tissue distributions. This review explores these issues and provides a summary of tissue concentrations of 11 currently licensed systemic antifungal agents. It also explores the therapeutic implications of their distribution at various sites of infection.

Oral therapy for onychomycosis: an evidence-based review

INTRODUCTION

Onychomycosis is a very common fungal infection of the nail apparatus; however, it is very hard to treat, even when the causative agent is identified, and usually requires prolonged systemic antifungal therapy. Until the 1990s, oral treatment options included only griseofulvin and ketoconazole, and the cure rate was very low. New generations of antimycotics, such as fluconazole, itraconazole and terbinafine have improved treatment success.

METHODS

Literature was identified by performing a PubMed Ovid MEDLINE, Ovid EMBASE, EBSCO CINAHL, and Literatura Latino-Americana e do Caribe em Ciências da Saúde (LILACS) search. Prospective and randomized clinical trials were chosen to be included in this review. Forty-six trials were included.

RESULTS

Fluconazole, itraconazole and terbinafine are effective in the treatment of onychomycosis and have a good safety profile. When a dermatophyte is the pathogen, terbinafine produces the best results. For Candida and nondermatophyte infections, the azoles, mainly itraconazole, are the recommended therapy.

CONCLUSION

In the majority of the studies, terbinafine treatment showed a higher cure ratio than the other drugs for dermatophyte onychomycosis.

[New apects in the diagnosis and therapy of dermatomycoses]

Recent observations indicate that Arthroderma benhamiae can cause bullous tinea, that onychomycosis increasingly occurs in children and that molds can cause tinea-like lesions. If a mycotic infection is suspected, the pathogen needs to be identified. The first genetic assays for the detection of dermatophytes have successfully been tested under routine conditions. Using appropriate techniques, genetic diagnosis is faster and more sensitive than a culture. Laboratory standards that would facilitate widespread implementation of genetic identification of dermatophytes have not yet been established. For the identification of yeasts, MALDI-TOF has already been established in many laboratories. This method is being refined for the diagnosis of hyphomycetes too. Newer antimycotics that are approved for certain systemic mycoses such as the triazoles voriconazole and posaconazole and the echinocandines caspofungin, micafungin und anidulafungin may be considered for dermatomycoses that cannot be treated by other therapies. Thermotherapy and photodynamic therapy are additional options in particularly difficult cases.

Posaconazole: the case for therapeutic drug monitoring

Invasive fungal infections are associated with high morbidity and mortality. Antifungal therapeutic options remain relatively limited; therefore, optimization of present regimens is essential. Posaconazole is licensed for prevention of invasive fungal infections and oropharyngeal candidiasis and salvage therapy for invasive aspergillosis. Recent data suggest that therapeutic drug monitoring may be an important tool for patient management. Clinical and laboratory animal data suggest that posaconazole demonstrates clinically relevant exposure-response relationships. Higher systemic drug exposure is associated with improved clinical outcomes. Potentially subtherapeutic concentrations are frequently encountered in critically ill patients. Therapeutic drug monitoring provides a way to optimize the use of posaconazole, and this review summarizes the indications and process by which this can be achieved.

Histopathology and antifungal treatment of experimental murine chromoblastomycosis caused by Cladophialophora carrionii

OBJECTIVES

A murine model of chromoblastomycosis caused by Cladophialophora carrionii was used to compare the efficacy of posaconazole and voriconazole with that of terbinafine and itraconazole, the currently used drugs in the management of chromoblastomycosis.

METHODS

Athymic nude mice were infected with 2 × 10(7) cfu of a clinical isolate of C. carrionii. When typical lesions were established, treatments with posaconazole at 20 mg/kg/day, voriconazole at 20 mg/kg/day, itraconazole at 50 mg/kg/day or terbinafine at 250 mg/kg/day were initiated. Treatment efficacy was evaluated for 4 months by measuring the size of the lesions, observing any histopathological changes and culturing the excised tissue.

RESULTS

Posaconazole was the only drug that reduced the initial lesion size, while voriconazole and terbinafine reduced growth relative to controls.

CONCLUSIONS

This study suggests that the newer triazoles have potential in the treatment of chromoblastomycosis caused by C. carrionii.

Determination of posaconazole levels in toenails of adults with onychomycosis following oral treatment with four regimens of posaconazole for 12 or 24 weeks

Pharmacokinetic data from a randomized, parallel-group, multicenter study are presented. Adults with toenail onychomycosis (n = 146) received posaconazole (100 mg, 200 mg, or 400 mg) once daily (QD) for 24 weeks or 400 mg QD for 12 weeks. The posaconazole concentration in the great toenail exhibited a dose-related increase starting at week 2 for 24 weeks and a mean toenail-to-plasma concentration ratio of approximately 3:1 at the end of treatment for the 400-mg 24-week dose.