Valérie Vroome

A General Overview on Past, Present and Future Antimycotics

Since the discovery of amphotericin B in 1955 the armamentarium of antimycotic drugs now embraces many new chemical classes: azoles, allylamines and candins. However, despite the wide variety in chemical structure, there is a lack of diversity in terms of mechanism of action. The mechanism of action of the main classes of antimycotics as well as the therapeutic value of some representatives is discussed. Some challenges to innovation will be highlighted that when overcome will herald more effective therapeutic interventions. Finally, we will list antimycotics that are at a late stage of development.

Activity of the Triazole Antifungal R126638 as Assessed by Corneofungimetry

Background: R126638 is a novel triazole exhibiting potent in vitro and in vivo antifungal activity against fungal pathogens including dermatophytes and yeasts. Objective: To determine the antifungal activity in time in the stratum corneum of healthy volunteers after oral intake of R126638 at a daily dose of 100 or 200 mg for 1 week. Method: Sixteen male volunteers were randomly allocated to oral treatment with either 100 or 200 mg of R126638 once daily for 1 week. Five cyanoacrylate skin surface strippings (CSSS) were obtained from the forearm of each subject before drug intake at day 1. CSSS were also collected during treatment at day 2 (24 h after the first drug intake, before the second drug intake), at day 4 (before the fourth drug intake) and at day 7 (10 h after the last drug intake). The post-treatment lingering effect was assessed at day 10 (3 days after treatment) and at day 14 (7 days after treatment). The corneofungimetry bioassay was performed on these CSSS to assess the antifungal profile of R126638. Cells of different fungal species (Trichophyton rubrum, Trichophyton mentagrophytes, Microsporum canis, Candida albicans and Malassezia globosa) were deposited and cultured for 10 days on CSSS in a sterile and controlled environment. The extent of fungal growth on the stratum corneum was determined using computerized image analysis. Results: R126638 clearly reduced the growth of all tested fungal species. The onset of effects of R126638 was evidenced at day 4 when it reached statistical significance for 3 of 5 species. At day 7, significance was reached for 4 of 5 species. During the posttreatment period, R126638 remained effective for 4 of 5 species at day 10, and this activity persisted until day 14 for 2 of 5 species. Conclusion: A broad spectrum antifungal activity was rapidly expressed in the stratum corneum after oral intake of R126638. The drug likely reached the upper layers of the stratum corneum by diffusion and persisted in this location for at least 7 days after treatment.

A fungicidal piperazine-1-carboxamidine induces mitochondrial fission-dependent apoptosis in yeast

To unravel the working mechanism of the fungicidal piperazine-1-carboxamidine derivative BAR0329, we found that its intracellular accumulation in Saccharomyces cerevisiae is dependent on functional lipid rafts. Moreover, BAR0329 induced caspase-dependent apoptosis in yeast, in which the mitochondrial fission machinery consisting of Fis1 (Whi2), Dnm1 and Mdv1 is involved. Our data are consistent with a prosurvival function of Fis1 (Whi2) and a proapoptotic function of Dnm1 and Mdv1 during BAR0329-induced yeast cell death.

A Pilot Study on Seborrheic Dermatitis Using Pramiconazole as a Potent Oral Anti-Malassezia Agent

Background: Seborrheic dermatitis is considered to be a Malassezia-driven disease. Little objective information is available so far from biometrological quantitative assessments of this skin condition. Pramiconazole is a novel triazole with potent in vitro antifungal activity, especially against Malassezia spp. Objective: To study the sequential effects of pramiconazole on Malassezia, inflammation and epidermal changes. Method:This study was performed in 2 groups of subjects suffering from seborrheic dermatitis. The first group (n = 17) remained untreated and was used as control. Clinical, mycological and biometrological assessments were performed at inclusion and during the following 2 weeks. The second group of subjects (n = 10) received a single 200-mg oral dose of pramiconazole at inclusion. Clinical, mycological and biometrological evaluations were performed before and during 1 month following the single antifungal intake. For both parts of the study, several parameters were assessed including yeast density, desquamation, erythema, itching and sebum excretion. Results: In the control group, no significant changes were observed in any of the parameters during the observation period. The findings were markedly different in the pramiconazole-treated subjects. The yeast density was significantly improved on days 3, 7 and 28. Desquamation, erythema, itching, and the global clinical evaluation as assessed by the patients and investigators became significantly improved on days 7 and 28. A trend in decrease of scaliness was noted. No effect on sebum excretion was evidenced. In conclusion, a single 200-mg dose of pramiconazole exhibitsin vivo efficacy in controlling some important clinical aspects of seborrheic dermatitis. Following a reduction in the number of yeasts on day 3, a decrease in the severity of clinical signs and symptoms occurred from day 7 onwards. Sebum excretion appeared uninvolved in the clearing process of seborrheic dermatitis. Conclusion: A single 200-mg dose of pramiconazole appears to abate seborrheic dermatitis. The density in Malassezia present on lesional skin is first decreased, followed by clearing of the clinical signs.

Dynamics of skin barrier repair following topical applications of miconazole nitrate.

The skin barrier function (SBF) is an important aspect of skin biology, particularly in the elicitation of inflammation. The SBF recovery rate after tape stripping and surfactant challenge can be assessed by measuring the transepidermal water loss (TEWL). Previous clinical studies have shown some inflammatory effect after topical applications of miconazole. The aim of this study was to compare the effect of pastes (petrolatum and 15% zinc oxide) containing or not miconazole nitrate on controlled impaired SBF. Fifteen volunteers were enrolled. In each subject, successive cyanoacrylate skin surface strippings were harvested from 5 sites of the volar forearm until TEWL raised above 15 g/cm2/h on all test sites. In addition, one daily soak session with a 0.2% dishwashing liquid further damaged the SBF. Each of the test formulations was applied twice daily for 5 days at two dosages, namely 1 and 2 mg/cm2, on randomized test sites. Another site remained untreated. TEWL was measured daily for 5 days. A fastened SBF repair was observed on all treated sites, particularly where the largest amount of the products had been applied. A faster SBF recovery rate was obtained at the site receiving the miconazole nitrate paste. We conclude that the occlusive effect of a paste helped mitigate SBF defect. The adjunction of miconazole nitrate improved the efficacy.

Novel fungicidal benzylsulfanyl-phenylguanidines

A series of substituted benzylsulfanyl-phenylamines was synthesized, of which four substituted benzylsulfanyl-phenylguanidines (665, 666, 667 and 684) showed potent fungicidal activity (minimal fungicidal concentration, MFC ≤ 10 μM for Candida albicans and Candida glabrata). A benzylsulfanyl-phenyl scaffold with an unsubstituted guanidine resulted in less active compounds (MFC=50-100 μM), whereas substitution with an unsubstituted amine group resulted in compounds without fungicidal activity. Compounds 665, 666, 667 and 684 also showed activity against single C. albicans biofilms and biofilms consisting of C. albicans and Staphylococcus epidermidis (minimal concentration resulting in 50% eradication of the biofilm, BEC50 ≤ 121 μM for both biofilm setups). Compounds 665 and 666 combined potent fungicidal (MFC=5 μM) and bactericidal activity (minimal bactericidal concentration, MBC for S. epidermidis ≤ 4 μM). In an in vivo Caenorhabditis elegans model, compounds 665 and 667 exhibited less toxicity than 666 and 684. Moreover, addition of those compounds to Candida-infected C. elegans cultures resulted in increased survival of Candida-infected worms, demonstrating their in vivo efficacy in a mini-host model.

Novelties in the multifaceted miconazole effects on skin disorders

Background: Miconazole nitrate is a time-honored antifungal of the imidazole class. Objective: To revisit the various aspects of action of the drug in a dermatologic setting. Method: Review of the current peer-reviewed publications. Results/conclusion: Miconazole essentially inhibits 14α-demethylase, an enzyme required for the biosynthesis of ergosterol, which is the main sterol constituent of fungal cell membranes. Hence, toxic methylated sterols accumulate. Synthesis of triglycerides and phospholipids is also affected. In addition, miconazole also exhibits other ancillary mechanisms of action that probably participate in the therapeutic efficacy of the drug. The oxidative and peroxidative enzyme activities are altered leading to an intracellular build up of a toxic concentration of hydrogen peroxide. This may contribute to the deterioration of subcellular organelles and to cell necrosis. Farnesol synthesis is stimulated in Candida spp. leading to the prevention of yeast-to-mycelium formation. Overall, miconazole is fungistatic through its effect on ergosterol biosynthesis, but it may also have a fungicidal effect against a number of fungal species due to its effect on hydrogen peroxide accumulation. In addition, miconazole is active against a series of Gram-positive bacteria and has been shown to help the repair of the skin barrier function and to help mitigate some inflammatory cell reactions (such as in acne). To conclude, miconazole exerts multi-pronged effects both against pathogenic fungi and on skin physiology.

Coping with mild inflammatory catamenial acne A clinical and bioinstrumental split-face assessment

Background: Acne is a multifactorial disease exhibiting distinct clinical presentations. Among them, the catamenial type is a matter of concern for young women. Some oral contraceptives may help without, however, clearing the skin condition.

Effect of a single overnight topical application of miconazole nitrate paste on acne papules.

Background  The classical management of acne calls for prolonged oral and/or topical treatments; however, some patients request a rapid effect to make the papules disappear within a few hours or days.

Corneofungimetry bioassay on Malassezia spp. under ketoconazole and desonide influences.

Background: Glucocorticoids can boost some Malassezia-driven dermatoses. However, both antifungals and topical corticosteroids improve lesions of seborrheic dermatitis. Objective: To revisit the topical activity of the antifungal ketoconazole and the corticosteroid desonide on Malassezia growth on human stratum corneum. Material and Methods: The computer-assisted corneofungimetry bioassay was used to compare the growth of M. furfur, M. globosa and M. restricta on human stratum corneum coated with olive oil. Four blinded gel formulations were tested. They contained either 2% ketoconazole, 0.05% desonide or a combination of 2% ketoconazole and 0.05% desonide; one gel was unmedicated. Untreated stratum corneum and specimens coated with a 2% ketoconazole cream were used as negative and positive comparators, respectively. A total of 45 samples (15 M. furfur, 15 M. globosa, and 15 M. restricta) were used for each test formulation in this randomized, double-blind study. Results: The 2% ketoconazole gel and cream and the combination of 2% ketoconazole and 0.05% desonide formulation abated similarly and significantly the M. furfur, M. globosa and M. restricta growth. The 3 species were similarly sensitive to these formulations. By contrast, no significant inhibitory effect was yielded by the 0.05% desonide gel and the vehicle. Conclusion: The presence of 0.05% desonide does not impair or improve the Malassezia susceptibility to 2% ketoconazole when growing on lipid-enriched human stratum corneum.