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Prototheca are unicellular, achlorophyllous, yeast-like microalgae that occur in a wide range of natural habitats. At least five species have been implicated as the causative agents of opportunistic infections of men. Human protothecosis typically manifests as cutaneous, articular, or systemic disease. Treatment is largely empirical with poorly predictable and often unsuccessful outcomes. This is largely due to the frequently observed resistance of Prototheca species to conventional antimicrobial agents. This work is the first to perform drug susceptibility profiling exclusively on isolates from human cases of protothecosis. A total of 23 such isolates were tested against amphotericin B and 9 azoles, including efinaconazole and luliconazole, whose activities against Prototheca have never been studied before. Efinaconazole was the most active, with median minimum inhibitory concentration (MIC) and minimum algicidal concentration (MAC) values of 0.031 mg/L and 0.063 mg/L, respectively. Fluconazole and luliconazole had the lowest activity, with median MIC and MAC values of 128 mg/L. To conclude, amphotericin B and most of the azoles showed in vitro activity, with an algicidal rather than algistatic effect, against Prototheca. Still, the activity of individual drugs differed significantly between the species and even between strains of the same species. These differences can be attributed to a species-specific potential for acquiring drug resistance, which, in turn, might be linked to the treatment history of the patient from whom the strain was recovered. The results of this study underscore the potential clinical utility of efinaconazole as a promising therapeutic agent for the treatment of human protothecosis.

A total of 62 Prototheca bovis isolates from cases of bovine mastitis were tested for susceptibility to different antifungal compounds by the Clinical and Laboratory Standards Institute (CLSI) reference microdilution method and a commercial colorimetric microdilution panel (Sensititre YeastOne). All isolates displayed low susceptibility to echinocandins (MICs > 8 μg/ml for anidulafungin, caspofungin, and micafungin), flucytosine (MIC > 64 μg/ml), and the azoles enilconazole and fluconazole (MICs > 4 and > 64 μg/ml, respectively). Moreover, 45.2, 32.3, and 1.6% of isolates had MICs > 4 μg/ml for ketoconazole, terbinafine, and voriconazole, respectively, when tested by the CLSI method. In contrast, all isolates were more susceptible to the polyene compounds amphotericin B and nystatin, and itraconazole, posaconazole, and ravuconazole (MICs ≤ 2 μg/ml, in all cases). Comparison of the results obtained in the CLSI and Sensititre methods showed excellent essential agreement (EA) for azoles (98.4% for itraconazole and posaconazole, and 100% for voriconazole) and moderate EA for amphotericin B (72.6%), when MICs were read after 48 and 24 h of incubation, respectively. In contrast, much lower EA values were obtained in some cases when the MICs for both techniques were determined after 48 h of incubation (e.g., 9.7% for amphotericin B and 69.4% for posaconazole). Therefore, the CLSI broth microdilution method and the Sensititre YeastOne panel can be used indistinctly for susceptibility testing of P. bovis isolates against azoles but not against amphotericin B until further optimization of the test conditions. Lay summary The antifungal susceptibility of Prototheca bovis isolates was analyzed. All tested isolates displayed low susceptibility to echinocandins, flucytosine, and some azoles. Excellent agreement of the results of two different test methods was obtained for azoles, but not for the polyene amphotericin B.

Over the past few decades, the dynamic progress in the synthesis and screening of heterocyclic compounds against various targets has made a significant contribution in the field of medicinal chemistry. Among the wide array of heterocyclic compounds, triazole moiety has attracted the attention of researchers owing to its vast therapeutic potential and easy preparation via copper and ruthenium-catalyzed azide-alkyne cycloaddition reactions. Triazole skeletons are found as major structural components in a different class of drugs possessing diverse pharmacological profiles including anti-cancer, anti-bacterial, anti-fungal, anti-viral, anti-oxidant, anti-inflammatory, anti-diabetic, anti-tubercular, and anti-depressant among various others. Furthermore, in the past few years, a significantly large number of triazole hybrids were synthesized with various heterocyclic moieties in order to gain the added advantage of the improved pharmacological profile, overcoming the multiple drug resistance and reduced toxicity from molecular hybridization. Among these synthesized triazole hybrids, many compounds are available commercially and used for treating different infections/disorders like tazobactam and cefatrizine as potent anti-bacterial agents while isavuconazole and ravuconazole as anti-fungal activities to name a few. In this review, we will summarize the biological activities of various 1,2,3-triazole hybrids with copious oxygen-containing heterocycles as lead compounds in medicinal chemistry. This review will be very helpful for researchers working in the field of molecular modeling, drug design and development, and medicinal chemistry.

Fosravuconazole L-lysine ethanolate (F-RVCZ), a ravuconazole prodrug, is a newly available agent with high expectations for efficacy in the treatment of onychomycosis. However, clinical data regarding the efficacy of F-RVCZ are limited because the drug was launched only in Japan in 2018. Therefore, we analyzed the outcome of F-RVCZ therapy in the treatment of onychomycosis at outpatient dermatology clinics in Japan. We examined data for 109 patients (68 male, 41 female) with varying clinical type, including total dystrophic onychomycosis and dermatophytoma, and a wide range of age groups, including the elderly. The complete cure rate at 12 weeks was 6.4% (7/109) and 67.9% (74/109) at the last visit (mean time to last visit: 32 ± 14.2 weeks). Mean rate of improvement in the affected nail area was 49.1 ± 23.3% at 12 weeks and 86.8 ± 22.4% at the last visit. Efficacy at 12 weeks and the last visit, respectively, was as follows: none, 4 cases and 1 case; slight, 35 cases and 4 cases; moderate, 51 cases and 21 cases; significant, 12 cases and 9 cases; complete cure, 7 cases and 74 cases. There were no serious adverse events. This retrospective survey was the first large-scale analysis of actual clinical practice outcomes and had minimal exclusions. Compared to previous reports, our results demonstrated excellent efficacy of F-RVCZ therapy in a variety of patients. Considering our results and the ease of oral administration (1 capsule/day for 12 weeks) and few adverse events, F-RVCZ therapy appears to be a useful option for the treatment of onychomycosis.

Chagas disease is a neglected tropical disease caused by the protozoan Trypanosoma cruzi. Currently, only nitroheterocyclic nifurtimox (NFX) and benznidazole (BNZ) are available for the treatment of Chagas disease, with limitations such as variable efficacy, long treatment regimens and toxicity. Different strategies have been used to discover new active molecules for the treatment of Chagas disease. Target-based and phenotypic screening led to thousands of compounds with anti-T. cruzi activity, notably the nitroheterocyclic compounds, fexinidazole and its metabolites. In addition, drug repurposing, drug combinations, re-dosing regimens and the development of new formulations have been evaluated. The CYP51 antifungal azoles, as posaconazole, ravuconazole and its prodrug fosravuconazole presented promising results in experimental Chagas disease. Drug combinations of nitroheterocyclic and azoles were able to induce cure in murine infection. New treatment schemes using BNZ showed efficacy in the experimental chronic stage, including against dormant forms of T. cruzi. And finally, sesquiterpene lactone formulated in nanocarriers displayed outstanding efficacy against different strains of T. cruzi, susceptible or resistant to BNZ, the reference drug. These pre-clinical results are encouraging and provide interesting evidence to improve the treatment of patients with Chagas disease.

Aspergillus species are emerging causative agents of non-dermatophyte mold onychomycosis. In this study, 48 Aspergillus isolates were obtained from patients with onychomycosis in Mashhad, Iran, during 2015–2018. The aim is to identify the Aspergillus isolates to the species level by using partial calmodulin and beta-tubulin gene sequencing and MALDI-TOF MS, and to evaluate their in vitro susceptibility to ten antifungal drugs: terbinafine, itraconazole, voriconazole, posaconazole, ravuconazole, isavuconazole, caspofungin, micafungin, anidulafungin and amphotericin B according to CLSI M38-A3. Our results indicate that A.flavus (n = 38, 79%) is the most common Aspergillus species causing onychomycosis in Mashhad, Iran. Other detected species were A. terreus (n = 3), A. tubingensis (n = 2), A. niger (n = 1), A. welwitschiae (n = 1), A. minisclerotigenes (n = 1), A. citrinoterreus (n = 1) and A. ochraceus (n = 1). Aspergillus flavus, A. terreus and A. niger isolates were correctly identified at the species level by MALDI-TOF MS, while all cryptic species were misidentified. In conclusion, A. flavus is the predominant Aspergillus species causing onychomycosis due to Aspergillus spp. in Mashhad, Iran. MALDI-TOF MS holds promise as a fast and accurate identification tool, particularly for common Aspergillus species. It is important that the current database of reference spectra, representing different Aspergillus species is expanded to increase the precision of the species-level identification. Terbinafine, posaconazole and echinocandins were in vitro most active against the studies Aspergillus isolates and terbinafine could be the first choice for treatment of onychomycosis due to Aspergillus.

Chagas disease (CD) is recognized as a neglected tropical disease. It is endemic of Latin America, but globalization has led to its spread worldwide. Even though its presence has been tracked at least 9000 years ago, treatment options remain scarce. The purpose of this review is to analyze the evidence for current and future options to combat the disease. CD patients benefit from dietary and exercise recommendations. Benznidazole and nifurtimox continue to be the available treatment options. Besides them, several drugs have been developed, repurposed, and tested in clinical trials, mostly inhibitors of the ergosterol synthesis like albaconazole, itraconazole, posaconazole, ravuconazole/fosravuconazole, voriconazole, and TAK-187; antiarrhythmics like amiodarone/dronedarone; inhibitors of the purine synthesis like allopurinol; nitroimidazoles like fexinidazole; and minerals like selenium. Even though they have shown in vitro and in vivo activity against Trypanosoma cruzi, their effectiveness is inferior to the one from benznidazole. Chronic CD patients who develop the cardio-digestive forms of the disease may eventually need assistive devices and/or surgical procedures to improve their outcome. Benznidazole and nifurtimox are the only trypanosomal drugs available to combat T. cruzi infection, and their effectiveness relies upon the stage of the disease at where the patients are. Their side effects frequently lead to patient’s non-compliance to treatment. Therefore, more effective drugs with a better safety profile are required. Up to date, controversial and promising results have been observed. Further compromise and research must be encouraged to tackle the challenges of developing new effective and safer drugs for CD patients.

Fosravuconazole is a novel oral antifungal drug developed in Japan and used to treat tinea unguium since 2018. Its excellent oral absorbability and systemic bioavailability has enabled short-duration therapy of 3 months. Furthermore, no concomitant drugs are contraindicated due to the presence of the mild inhibitor of cytochrome P450 enzyme which is responsible for polypharmacy adverse effects. Therefore, it can be safely administrated to elderly patients. Elderly patients (≥65 years old) with severe onychomycosis (≥50% nail involvement) were treated with oral fosravuconazole 100 mg once daily for 12 weeks. The rate of involvement improved from 86.6% to 28.1% (P < 0.01). The efficacy (i.e. percentage of those rated as "improved" and better) and cure rate was 83.8% (31/37) and 29.7% (11/37), respectively. Furthermore, when focusing on the thin nail group (

Ravuconazole (RVCZ) is a new human anti-fungal azole drug available in Japan since 2018 and is a broad-spectrum agent that exhibits excellent activity against dermatophytes. In the present study, the in vitro RVCZ susceptibility of clinical isolates of anthropophilic dermatophytes, including Trichophyton interdigitale strains with either low susceptibility to itraconazole (ITCZ) or resistance to terbinafine (TEBR), was investigated using the Clinical & Laboratory Standards Institute M38-A2 test. The MICs of RCVZ for 20 clinical isolates of T. interdigitale were < 0.03125-0.125 mg/L; for 4 clinical isolates of T. rubrum, < 0.03125-0.0625 mg/L; and for 20 clinical isolates of T. tonsurans, < 0.03125 mg/L. Similarly, the MICs of RCVZ for the T. interdigitale strains with either low susceptibility to ITCZ or resistance to TEBR were also < 0.03125 mg/L. To our knowledge, this is first study to investigate the in vitro RVCZ susceptibility of T. interdigitale strains with either low susceptibility to ITCZ or resistance to TEBR. Our results indicated that RVCZ was the most effective drug against these strains.

In order to explore novel antifungal agents, twenty-seven triazole derivatives featuring an alkyne linker in the side chain were designed and synthesized by the Sonogashira reaction. Most of the target compounds exhibited good antifungal activity against eight human pathogenic fungi, especially excellent activity against Candida and Cryptococcus species, comparing with the reference drugs fluconazole, voriconazole and ravuconazole. Compounds A2 and A3 exhibited in vitro activity against all the tested fungi with MIC80 values ranging from 0.0156 μg/mL to 0.5 μg/mL, which are superior to ravuconazole and fluconazole. SAR and molecular docking study give a clear conclusion that para-fluoro, para-chloro, and para-cyano substituted phenylalkynyl or pyridinylalkynyl side chains may promote triazole antifungal activity. Keywords: Triazole, Alkyne, CYP51, Antifungal, Synthesis

We investigated the antifungal susceptibility profiles of 207 independent Candida albicans strains isolated from patients with vulvovaginal candidiasis (VVC) in Xinjiang Province of China. Using CLSI M27-A3 and M27-S4 guidelines, anidulafungin and micafungin were the most active drugs against C. albicans showing an MIC50/MIC90 corresponding to 0.016/0.0313 µg/mL, followed by caspofungin (0.25/0.25 µg/mL), posaconazole (0.125/0.5 µg/mL), ravuconazole (0.063/1 µg/mL), itraconazole (0.125/1 µg/mL), amphotericine B (0.5/1 µg/mL), isavuconazole (0.063/2 µg/mL), 5-flucytosine (1/2 µg/mL), voriconazole (0.125/4 µg/mL), and fluconazole (0.5/4 µg/mL). 96.1% (199)–100.0% (207) isolates were sensitive to the three echinocandins tested, amphotericine B and 5-flucytosine. The in vitro activity of triazoles against all isolates tested was variable; itraconazole and voriconazole had reduced the activity to almost half of the isolates (55.1% (114) and 51.2% (106) susceptible, respectively). Fluconazole was active against 76.3% (158) isolates tested. The new triazoles ravuconazole, isavuconazole and posaconazole showed good in vitro potency against 89.9% (186)–95.2% (197) of isolates with the geometric mean MIC (µg/mL) of 0.10, 0.12 and 0.14 µg/mL, respectively. In conclusion, our study indicates that for effective management of systemic candidiasis in Xinjiang Province of China, it is important to determine the susceptibility profiles of isolated C. albicans from patients with VVC.

BackgroundOnychomycosis is one of the most common and recurrent dermatological diseases worldwide. The antimycotic activity of prescribed medications varies according to the causative agents, and treatment failure rates exceeding 30%. This study aimed to assess the epidemiological profile of onychomycosis in Iran. Also, the susceptibilities to conventional and new antifungals were investigated.MethodsIn this descriptive cross-sectional study, during the period of 18 months starting from September 2019 until March 2020, 594 nail specimens were obtained from patients who presented nail changes compatible with a clinical diagnosis of onychomycosis. The patients were referred from different cities, including Tehran, Kermanshah, Arak, Kashan, Rasht, Qom, Urmia, Zahedan, Hamadan, Zanjan, Borujerd, Bushehr, and Yazd. All the samples were subjected to microscopic examination and fungal culture. Fungi identified were confirmed through the PCR-sequencing method. The susceptibility to itraconazole, fluconazole, terbinafine, griseofulvin, posaconazole, ravuconazole, efinaconazole, luliconazole, and tavaborole was evaluated according to the Clinical and Laboratory Standards Institute (CLSI) guidelines, document M38-A2 for filamentous fungi, and document M27-A3 for yeasts.Results594 patients were included. Of these, in 179 cases (30.1%) (95% CI:0.3 ± 0.037) onychomycosis was confirmed. The majority of patients were ≥ 60 years of age (n=58, 32.6%) and female (n=113, 63.1%). Saprophytic fungi accounted for the vast majority of the nail isolates (n=92, 51.4%) (95% CI:0.051 ± 0.0.073), followed by dermatophytes (n=45, 25.1%) (95% CI:0.25 ± 0.063), and yeasts (n=42, 23.5%) (95% CI:0.23 ± 0.061). Diabetes mellitus (77.3%), hypothyroidism (18.2%), and solid tumors (4.5%) were documented as the most prevalent underlying conditions. Antifungal susceptibility testing was performed against 60 fungal isolates (20 each of Candida species, saprophytic fungi, and dermatophytes). Efinaconazole, ravuconazole, and luliconazole were the most active agents against Candida species. Also, luliconazole, posaconazole, and efinaconazole were most potent against dermatophytes. Luliconazole had the greatest antifungal activity against saprophytic fungi.ConclusionsThe prevalence of onychomycosis in Iranian patients was relatively high. LUL exhibited potent antifungal activity against the three groups of fungi tested, determining its broad-spectrum antimycotic activity and its probable use as the first-line therapy for onychomycosis.

Mucormycosis is a life-threatening opportunistic infection caused by certain members of the fungal order Mucorales. This infection is associated with high mortality rate, which can reach nearly 100% depending on the underlying condition of the patient. Treatment of mucormycosis is challenging because these fungi are intrinsically resistant to most of the routinely used antifungal agents, such as most of the azoles. One possible mechanism of azole resistance is the drug efflux catalyzed by members of the ATP binding cassette (ABC) transporter superfamily. The pleiotropic drug resistance (PDR) transporter subfamily of ABC transporters is the most closely associated to drug resistance. The genome of Mucor circinelloides encodes eight putative PDR-type transporters. In this study, transcription of the eight pdr genes has been analyzed after azole treatment. Only the pdr1 showed increased transcript level in response to all tested azoles. Deletion of this gene caused increased susceptibility to posaconazole, ravuconazole and isavuconazole and altered growth ability of the mutant. In the pdr1 deletion mutant, transcript level of pdr2 and pdr6 significantly increased. Deletion of pdr2 and pdr6 was also done to create single and double knock out mutants for the three genes. After deletion of pdr2 and pdr6, growth ability of the mutant strains decreased, while deletion of pdr2 resulted in increased sensitivity against posaconazole, ravuconazole and isavuconazole. Our result suggests that the regulation of the eight pdr genes is interconnected and pdr1 and pdr2 participates in the resistance of the fungus to posaconazole, ravuconazole and isavuconazole.

E1224 is a prodrug of ravuconazole (RVZ), an antifungal drug with promising anti-Trypanosoma cruzi activity, the causative organism of Chagas disease (CD). This study was designed to assess the pharmacokinetics (PK) and safety interactions of benznidazole (BNZ), the drug of choice for treatment of CD, and E1224 in healthy volunteers., E1224 is a prodrug of ravuconazole (RVZ), an antifungal drug with promising anti-Trypanosoma cruzi activity, the causative organism of Chagas disease (CD). This study was designed to assess the pharmacokinetics (PK) and safety interactions of benznidazole (BNZ), the drug of choice for treatment of CD, and E1224 in healthy volunteers. This open-label, single-center, sequential, single- and multiple-oral-dose study enrolled 28 healthy male subjects. These subjects received BNZ (2.5 mg/kg) once daily on days 1 and 9 and twice daily from day 12 to day 15 and E1224 once daily from day 4 to day 15 (loading dose of 400 mg for 3 days and maintenance dose of 100 mg for 9 days). The maximum concentration (Cmax) and area under the concentration curve from zero to infinity for BNZ were comparable, whether BNZ was given alone or with E1224 at steady state, with ratios of geometric means for BNZ-RVZ to BNZ of 0.96 and 0.83 and corresponding 90% confidence intervals (CIs) of 0.91 to 1.10 and 0.80 to 0.87, respectively. However, RVZ Cmax and area under the concentration curve from zero to 24 h increased by about 35% when concomitantly administered with BNZ at steady state (ratio of geometric means for RVZ-BNZ/RVZ of 1.31 and 1.36 and corresponding 90% CIs of 1.23 to 1.39 and 1.31 to 1.41, respectively). Both compounds were well tolerated. There were no clinically relevant safety interactions between E1224 and BZN. Given these results, coadministration of RVZ and BNZ should not require any adaptation of E1224 dosing.

Background Ravuconazole is an extended-spectrum triazole agent that is efficient in vitro against Candida spp. and has been approved to work as an oral formulae for onychomycosis in Japan in 2018. However, nobody had determined the MIC of ravuconazole against the Candida auris, which is known as an emerging multidrug-resistant yeast. Meanwhile, rare is known of the in vitro activity of ravuconazole against vaginal Candida isolates. Objectives To investigate the activity of ravuconazole against C. auris and vaginal Candida isolates of China and assess the feasibility of ravuconazole in the treatment of candidiasis caused by C. auris and other Candida spp. Methods We determined the in vitro activity of ravuconazole and 9 comparators against 15 C. auris isolates and determined the MIC of ravuconazole on 525 vaginal Candida isolates (Candida albicans, Candida tropicalis, Candida glabrata and Candida parapsilosis) from 9 provinces of China by Clinical and Laboratory Standards Institute (CLSI) methodology. Results The MICs of fluconazole and amphotericin B on C. auris were much higher than second-generation azoles and echinocandins. Ravuconazole was active against all the C. auris isolates and as effective as isavuconazole, posaconazole and echinocandins while showed a better antifungal activity than itraconazole, voriconazole to C. auris. For vaginal Candida isolates, the proportion of ravuconazole-resistant isolates is 0.19% (1/525). Conclusions Ravuconazole was in good active against C. auris and vaginal Candida isolates, which suggested ravuconazole could be used in the treatment of drug-resistant candidiasis.

One path toward identifying effective and easily accessible antifungals is to repurpose commonly used drugs. Amiloride, a widely used diuretic, inhibits different isoforms of Na+/H+ exchangers, Na+ channels, and Na+/Ca2+ exchangers. Here, we found that amiloride had poor antifungal activity against isolates of Cryptococcus prompting the examination of the amiloride analog, HMA [5-(N,N-hexamethylene)amiloride]. HMA possesses strong activity against Na+/H+ exchangers (NHEs) and little K+-associated toxicity since HMA has only minimal inhibitory effects toward epithelial sodium channels (ENaC), the diuretic and antikaliuretic target of amiloride. Although HMA produced a robust dose-dependent growth inhibition of several fungal isolates, susceptibility assays revealed modest MICs against isolates of Cryptococcus. A checkerboard dilution strategy resulted in fractional inhibitory concentrations (FIC) < 0.5, suggesting that HMA displays synergy with several antifungal azole drugs including posaconazole, voriconazole, and ketoconazole. Itraconazole and ravuconazole showed moderate synergy with HMA across all tested fungal isolates. In combination with HMA, ravuconazole had MICs of 0.004–0.008 μg/ml, a ∼16-fold reduction compared to MICs of ravuconazole when used alone and significantly more effective than the overall MIC90 (0.25 μg/ml) reported for ravuconazole against 541 clinical isolates of Cryptococcus neoformans. In combination with azole drugs, MICs of HMA ranged from 3.2 μM (1 μg/ml) to 26 μM (16 μg/ml), HMA was not cytotoxic at concentrations ≤ 8 μg/ml, but MICs were above the reported HMA Ki of 0.013–2.4 μM for various Na+/H+ exchangers. Our results suggest that HMA has limited potential as a monotherapy and may have additional targets in fungal/yeast cells since strains lacking NHEs remained sensitive to HMA. We determined that the hydrophobic substituent at the 5-amino group of HMA is likely responsible for the observed antifungal activity and synergy with several azoles since derivatives with bulky polar substitutions showed no activity against Cryptococcus, indicating that other 5-substituted HMA derivatives could possess stronger antifungal activity. Moreover, substitution of other positions around the pyrazine core of HMA has not been investigated but could reveal new leads for antifungal drug development.

Trypanosomatidae family belongs to the Kinetoplastida order, which consists of obligatory parasites that affect plants and all classes of vertebrates, especially humans and insects. Among the heteroxenic parasites, Leishmania spp., Trypanosoma cruzi, and T. brucei are protozoa of most significant interest for medicinal chemistry, being etiological agents of Leishmaniasis, Chagas, and Sleep Sickness diseases, respectively. Currently, inefficient pharmacotherapy, especially in chronic phases and low selectivity towards parasite/host cells, justifies the need to discover new drugs to treat them effectively. Among other targets, the sterol 14α-demethylase (CYP51), an enzyme responsible for ergosterol's biosynthesis in Trypanosomatidae parasites, has received more attention in the development of new bioactive compounds. In this context, antifungal ravuconazole proved to be the most promising drug among this class against T. cruzi, being used in combined therapy with Bnz in clinic trials. Non-antifungal inhibitors, such as VFV and VNF, have shown promising results against T. cruzi and T.brucei, respectively, being tested in Bnz-combined therapies. Among the experimental studies involving azoles, compound (15) was found to be the most promising derivative, displaying an IC50 value of 0.002 µM against amastigotes from T. cruzi, in addition to being non-toxic and highly selective towards TcCYP51 (< 25 nM). Interestingly, imidazole analog (16) was active against infectious forms of these three parasites, demonstrating Ki values of 0.17, 0.02, and 0.36 nM for CYP51 from T. cruzi, T. brucei, and L. infantum. Finally, this review will address promising inhibitors targeting sterol 14α-demethylase (CYP51) from Trypanosomatidae parasites, highlighting SAR studies, interactions with this target, and recent contributions and advances in the field, as well.

We report a case of contact dermatitis caused by both efinaconazole, a topical triazole antifungal drug, and luliconazole, a topical imidazole antifungal drug. Positive patch test reactions were observed with efinaconazole and luliconazole. A patch test with lanoconazole also elicited a positive reaction. We hypothesized that structural similarity between luliconazole and lanoconazole led to cross-reaction, and that the dithiolane ring common to both drugs or the structure of the vinyl imidazole with a dithiolane ring could be the antigenic determinant. Since efinaconazole and luliconazole have no common structures, patients could be sensitized to both drugs separately. The antigenic determinant of efinaconazole is unknown. However, the chemical formula of ravuconazole, an oral triazole antifungal drug, is similar to that of efinaconazole. Clinicians should carefully consider potential cross-reactivity between these drugs.

The in vitro activities of 11 antifungals against 84 dematiaceous fungi were tested. For most tested fungal species, the MIC values of ravuconazole and isavuconazole were lower than those obtained with itraconazole, voriconazole, and posaconazole. Ravuconazole and isavuconazole appear to be more efficient against most dematiaceous fungal infections than the other triazoles. However, some pigmented fungi, such as Bipolaris spicifera and Veronaea botryosa , remain more susceptible to other triazoles or to echinocandins.

Aspergillus species are the most common causative agents involved in otomycosis. In this study, 45 Aspergillus isolates were obtained from patients with otomycosis in western China during 2013-2016. The aim of this study is to identify the Aspergillus isolates to the species level by using β-tubulin gene sequencing and to evaluate their in vitro susceptibility to nine antifungal drugs: amphotericin B, itraconazole, voriconazole, posaconazole, ravuconazole, isavuconazole, caspofungin, micafungin and anidulafungin according to CLSI M38-A2. Our results indicate that A. tubingensis (18/45) is the predominant Aspergillus species causing ear infections in western China, which is three times more than its sibling species A. niger (6/45) and A. welwitschiae (2/45). Other detected species were A. fumigatus (n = 8), A. terreus (n = 7) and A. flavus (n = 4). Antifungal susceptibility data indicate that triazoles and echinocandins are active against the most Aspergillus isolates. There are no significant differences in the susceptibility among A. niger, A. tubingensis and A. welwitschiae to each of the antifungals tested. One azole-resistant A. fumigatus isolate with a TR34/L98H mutation in the CYP51A gene and one posaconazole-resistant A. terreus isolate presented among the studied isolates. In conclusion, A. tubingensis is the most prevalent Aspergillus species causing otomycosis in western China. Posaconazole and echinocandins are potential drugs for treatment of otomycosis due to Aspergillus; however, in vivo efficacy remains to be determined.

Ravuconazole is a fourth generation azole exerting strong antifungal activity, with low drug-drug interaction and hepatic dysfunction risks. Fosravuconazole l-lysine ethanolate (fosravuconazole; NAILIN® Capsules 100 mg) was developed as a ravuconazole prodrug. Ravuconazole exerts strong antifungal activity against various pathogenic fungi including dermatophytes and Candida. Through prodrug formation, pharmacokinetic improvement was achieved, and bioavailability after oral administration reached 100%. The plasma ravuconazole concentration became 10-35 times higher than with current oral anti-onychomycosis drugs, and showed good skin and nail tissue transition plus tissue retention. This improvement obtained with fosravuconazole reflects its superior pharmacokinetic properties. We conducted a clinical trial with fosravuconazole orally administered once a day (100 mg ravuconazole) for 12 weeks in Japanese onychomycosis patients. The ravuconazole concentration in nail tissues exceeded the MIC90 against dermatophytes, even after treatment completion. Furthermore, the placebo-controlled, double-blind, comparative trial showed significantly superior effects (at 48 weeks after starting treatment, with a complete cure rate of 59.4%, a marked clinical improvement rate of 83.1%, and a mycological cure rate by direct microscopy of 82.0%). The major adverse reactions were laboratory abnormalities and gastrointestinal disorders with no severe symptoms, suggesting good tolerability. Fosravuconazole has fewer drug-drug interactions, is not affected by food, and is also expected to improve medication adherence since the administration period is only 12 weeks and there is no drug-free period as required with pulse therapy. Thus, fosravuconazole has many favorable pharmacological properties and can reasonably be expected to become a new oral treatment option for onychomycosis.

Aspergillus species are the most common pathogenic fungi involved in otomycosis, an infection of the outer ear canal. In this study, we examined the incidence of Aspergillus infections and the antifungal susceptibilities of 30 Aspergillus species isolates from patients with otomycosis who visited Saiseikai Utsunomiya Hospital between August 2013 and July 2016. Based on the morphological test results, the strains were identified as Aspergillus niger sensu lato (20 strains), A. terreus sensu lato (7 strains), and A. fumigatus sensu lato (3 strains). In contrast, the molecular identifications based on analyzing the isolates' partial β-tubulin gene sequences revealed them to be A. niger sensu stricto (12 strains), A. tubingensis (8 strains), A. terreus sensu stricto (7 strains), and A. fumigatus sensu stricto (3 strains). The antifungal susceptibility test results indicated that strains of A. tubingensis and A. niger sensu stricto displayed lower susceptibilities to ravuconazole, compared with the other isolates. The Aspergillus strains from this study showed low minimum inhibitory concentrations toward the azole-based drugs efinaconazole, lanoconazole, and luliconazole. Therefore, these topical therapeutic agents may be effective for the treatment of otomycosis.

Fosravuconazole L‐lysine ethanolate (F‐RVCZ) is a prodrug of ravuconazole, a novel triazole antifungal agent, exerting broad and potent antifungal activity. The efficacy and safety of F‐RVCZ, compared with a placebo, were investigated in a multicenter, double‐blind, randomized study of Japanese onychomycosis patients with 25% or more clinical involvement of the target toenail. Subjects (n = 153) were randomly assigned to receive F‐RVCZ (100 mg RVCZ, n = 101) or placebo (n = 52) p.o. once daily for 12 weeks. The primary end‐point was the rate of complete cure (clinical cure [0% clinical involvement of the target toenail] plus mycological cure [negative potassium hydroxide examination]) at week 48 (36‐week post‐treatment visit). Secondary end‐points were changes over time in the efficacy and mycological effect of F‐RVCZ. Safety was also evaluated. The complete cure rate at week 48 was significantly higher with F‐RVCZ (59.4%, 60/101) than the placebo (5.8%, 3/52) in the full analysis set (P < 0.001). The mycological cure rate at week 48 was also significantly higher with F‐RVCZ (82.0%, 73/89) than the placebo (20.0%, 10/50, P < 0.001). Regarding safety, adverse events were observed in 83.2% (84/101) and 80.8% (42/52), and adverse drug reactions (ADR) in 23.8% (24/101) and 3.8% (2/52) of F‐RVCZ and placebo subjects, respectively. ADR were mild to moderate in severity, with none being serious. F‐RVCZ (equivalent to 100 mg ravuconazole) administrated once daily for 12 weeks was more effective than placebo and tolerable in patients with onychomycosis, suggesting it to be a promising drug for onychomycosis treatment.

BFE1224, prodrug of ravuconazole, is a novel, once-daily, oral, triazole antifungal drug, and currently in development for the treatment of onychomycosis. The clinical drug-drug interaction (DDI) potential of BFE1224 with cytochrome P450 (CYP) and transporter was assessed by using two types of cocktails in healthy subjects in separate clinical studies. The CYP and transporter cocktails consisted of caffeine/tolbutamide/omeprazole/dextromethorphan/midazolam used in study 1 and digoxin/rosuvastatin used in study 2. In addition, repaglinide was separately administered to the same subjects in study 2. There were no major effects on the pharmacokinetics of CYP and transporter substrates, except for an approximate threefold increase in midazolam exposure after oral administration of BFE1224. The clinical DDIs of BFE1224 were mild for CYP3A and minor for other major CYPs (CYP1A2/2C8/2C9/2C19/2D6) as well as those of P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), organic anion transporting polypeptide (OATP) 1B1, and OATP1B3.

Protothecosis is a rare infection in humans, dogs, and cats, and its causative agent is Prototheca species, which consists of achlorophyllic algae that are ubiquitous in natural environments and hosts intestinal flora. Ravuconazole (RVZ) is a new available human azole drug in Japan since 2018 and broad-spectrum antifungal agent. In the present study, the in vitro susceptibility of clinical and environmental isolates of P. wickerhamii, P. zopfii, and P. blaschkeae to itraconazole (ITZ) voriconazole (VRZ), posaconazole (PCZ), and RVZ. RVZ was more potent than the other azoles against Protheca species and has considerable potential for use as a therapeutic agent for human and animal protothecosis.