Penetration Profiles of Four Topical Antifungals in Mycotic Human Toenails Quantified by Matrix-Assisted Laser Desorption Ionization-Fourier Transform Ion Cyclotron Resonance Imaging

INTRODUCTION

Onychomycosis is a fungal infection of the nails that can be challenging to treat. Here, matrix-assisted laser desorption ionization-Fourier transform ion cyclotron resonance (MALDI-FTICR) imaging was applied to the quantitative analysis of the penetration profile of the antifungal compound, amorolfine, in human mycotic toenails. The amorolfine profile was compared with those of three other antifungals, ciclopirox, naftifine, and tioconazole.

METHODS

Antifungal compounds (amorolfine 5% lacquer, ciclopirox 8% lacquer, naftifine 1% solution, and tioconazole 28% solution) were applied to mycotic nails (n = 42). Nail sections were prepared, and MALDI-FTICR analysis was performed on the sections at a spatial resolution of 70 μm to compare the distribution profiles. Based on the minimum inhibitory concentrations of the four test compounds needed to kill 90% (MIC90) of the fungal organism, Trichophyton rubrum, the fold differences between the MIC90 and the antifungal concentrations in the nails (termed the multiplicity of the MIC90) were calculated for each.

RESULTS

The penetration profiles indicated higher concentrations of amorolfine and ciclopirox in the deeper layers of the nails 3 h after treatment, compared with naftifine and tioconazole. The mean concentrations across the entire nail sections at 3 h were significantly different among the four antifungals: amorolfine, 2.46 mM; ciclopirox, 0.95 mM; naftifine, 0.63 mM; and tioconazole, 1.36 mM (p = 0.016; n = 8 per compound). The median multiplicity of the MIC90 at 3 h was 191-fold for amorolfine, tenfold for ciclopirox, 52-fold for naftifine, and 208-fold for tioconazole.

CONCLUSION

In this study, MALDI-FTICR was successfully applied to the quantitative analysis of antifungal distribution in human mycotic nails. The findings suggest that amorolfine penetrates deeper layers of the nail and accumulates at concentrations far exceeding the MIC needed to exert antimycotic activity.

In vitro determination of the combination of ciclopirox and terbinafine in the treatment of dermatophytosis

INTRODUCTION

The cases of dermatophytosis are increasing and they are associated with a higher number of therapeutic failures leading the doctor to prescribe combinations of antifungals as therapy. The objective was to evaluate the interaction of terbinafine and ciclopirox, the most commonly antifungals used in the clinic, in dermatophyte isolates.

METHODOLOGY

The minimum inhibitory concentrations (MIC) of ciclopirox and terbinafine were determined by the broth microdilution method according CLSI and the checkerboard assay was used to evaluate the interaction between the antifungal agents.

RESULTS

For terbinafine the mic50 was 0.125 ug/mL and mic90 was 0.250 ug/mL. For ciclopirox the values were 2.0 ug/mL for mic50 and 4.0 ug/mL for mic90. No synergistic interaction was observed for the dermatophyte isolates tested.

CONCLUSION

These results suggest that the use of terbinafine in combination with ciclopirox, which is widely used in the clinic, may not be a good choice for the treatment of onychomycosis.

Ciclopirox mitigates inflammatory response in LPS-induced septic shock via inactivation of SORT1-mediated wnt/β-Catenin signaling pathway

OBJECTIVE

Septic shock, the most severe stage of sepsis, is a deadly inflammatory disorder with high mortality. Ciclopirox (CPX) is a broad-spectrum antimycotic agent which also exerts anti-inflammatory effects in human diseases. However, whether CPX can relieve inflammatory response in LPS-induced septic shock remains unclear.

MATERIALS AND METHODS

Male C57BL/6 mice LPS were injected intraperitoneally with LPS to simulate septic shock in vivo. RAW264.7 cells and bone marrow-derived macrophages (BMDMs) were subject to LPS treatment to simulate septic shock in vitro. ELISA was applied to detect the level of pro-inflammatory cytokines. Cell viability was assessed by CCK-8 assay. Protein levels was detected by western blotting.

RESULTS

CPX enhanced the survival rate and attenuated inflammation in mice with LPS-induced septic shock. Similarly, CPX dose-dependently mitigated LPS-induced inflammation in BMDMs. It was also found that Sortilin 1 (SORT1) was upregulated in both in vivo and in vitro models of LPS-induced septic shock. In addition, SORT1 overexpression counteracted the alleviative effects of CPX on the inflammation response of LPS-challenged BMDMs by activating the Wnt/β-Catenin signaling. Furthermore, BML-284 (a Wnt/β-Catenin agonist) treatment also abrogated CPX-mediated moderation of LPS-triggered inflammatory reaction in BMDMs.

CONCLUSIONS

In sum, we found that CPX protected against LPS-induced septic shock by mitigating inflammation via SORT1-mediated Wnt/β-Catenin signaling pathway.

Hydroxypropyl chitosan nail lacquer of ciclopirox-PLGA nanocapsules for augmented in vitro nail plate absorption and onychomycosis treatment

Onychomycosis accounts for 90% of nail infections worldwide. Topical therapy provides localized effects with minimal adverse systemic actions, yet its effectiveness is limited by minimal drug permeation through the keratinized nail plate. Ciclopirox (CIX) is a FDA-approved broad-spectrum antimycotic agent. However, the complete cure with its nail lacquer (8% w/v) may continue for one year with a high cost. Therefore, poly lactide-co-glycolide (PLGA) nanocapsules (NCs) of CIX were prepared by nanoprecipitation and optimized through a 2³ factorial design to be incorporated into hydroxypropyl chitosan (HPCH) based nail lacquer. Nail hydration, in vitro nail absorption, minimum inhibitory concentration (MIC), inhibition zones and ex vivo fungal growth on nail fragments were evaluated. The optimized NCs of CIX based on 100 mg PLGA 2 A and lipoid S75 showed a mean diameter of 174.77 ± 7.90 nm, entrapment efficiency (EE%) of 90.57 ± 0.98%, zeta potential (ZP) of -52.27 ± 0.40 mV and a prolonged drug release. Nail lacquer of the optimized NCs exhibited a higher stability than NCs dispersion. Compared to CIX solution (1% w/v), the respective decrease in MIC for NCs and their lacquer was four- and eight-fold. The lacquer superiority was confirmed by the enhancement in the nail hydration and absorption by 4 and 2.60 times, respectively, relative to CIX solution and the minimal ex vivo fungal growth. Therefore, HPCH nail lacquer of (1% w/v) CIX-PLGA-NCs can be represented as a potential topical delivery system for enhanced in vitro nail absorption and therapeutic efficacy against onychomycosis at a low dose.

Synthetic derivatives of the antifungal drug ciclopirox are active against herpes simplex virus 2

We previously showed that the anti-fungal drug ciclopirox olamine effectively inhibits replication of herpes simplex virus (HSV)-1 and HSV-2. Given the rise of HSV strains that are resistant to nucleos(t)ide analog treatment, as well as the incomplete efficacy of nucleos(t)ide analogs, new inhibitory compounds must be explored for potential use in the treatment of HSV infection. In the present study, we analyzed 44 compounds derived from the core structure of ciclopirox olamine for inhibitory activity against HSV. Thirteen of these derivative compounds inhibited HSV-2 replication by > 1000- to ∼100,000-fold at 1 μM and displayed EC50 values lower than that of acyclovir, as well as low cytotoxicity, indicating their strong therapeutic potential. Through structural comparison, we also provide evidence for the importance of various structural motifs to the efficacy of ciclopirox and its derivatives, namely hydrophobic groups at R4 and R6 of the ciclopirox core structure. Like ciclopirox, representative analogs exhibit some oral bioavailability but are rapidly cleared in vivo. Together, these results will guide further development of N-hydroxypyridones as HSV therapeutics.

Ciclopirox inhibits NLRP3 inflammasome activation via protecting mitochondria and ameliorates imiquimod-induced psoriatic inflammation in mice

The maturation and secretion of interleukin-1β (IL-1β) mediated by NLRP3 inflammasome activation plays an important role in the progression of many inflammatory diseases. Inhibition of NLRP3 inflammasome activation may be a promising strategy to treat these inflammation-driven diseases, such as psoriasis. As a broad-spectrum antifungal agent, ciclopirox (CPX) is widely used in the treatment of dermatomycosis. Although CPX has been reported to have anti-inflammatory effects in many studies, there has been little research into its underlying mechanisms. In our study, CPX reduced lipopolysaccharide (LPS)/nigericin-induced NLRP3 inflammasome activation (IC₅₀: 1.684 μM). Mechanistically, CPX upregulated peroxisome proliferator-activated receptor-γ coactivator-1α expression (by 82.7% at 5 μM and 87.5% at 10 μM) to protect mitochondria. Our studies showed that CPX reduced mitochondrial reactive oxygen species production, increased mitochondrial membrane potential, elevated mitochondrial biosynthesis, and up-regulated intracellular adenosine triphosphate level. Furthermore, treatment with CPX promoted the up-regulation of mRNA expression, which involved mitochondrial biosynthesis (NRF1, NRF2, TFAM) and antioxidation (SOD1 and CAT). In addition, CPX ameliorated inflammatory response in imiquimod-induced psoriasis mice. This study provides a potential pharmacological mechanism for CPX to treat psoriasis and other NLRP3-driven inflammatory diseases.

Ciclopirox targets cellular bioenergetics and activates ER stress to induce apoptosis in non-small cell lung cancer cells

Background

Lung cancer remains a major cause of cancer-related mortality throughout the world at present. Repositioning of existing drugs for other diseases is a promising strategy for cancer therapies, which may rapidly advance potentially promising agents into clinical trials and cut down the cost of drug development. Ciclopirox (CPX), an iron chelator commonly used to treat fungal infections, which has recently been shown to have antitumor activity against a variety of cancers including both solid tumors and hematological malignancies in vitro and in vivo. However, the effect of CPX on non-small cell lung cancer (NSCLC) and the underlying mechanism is still unclear.

Methods

CCK-8, clonal formation test and cell cycle detection were used to observe the effect of inhibitor on the proliferation ability of NSCLC cells. The effects of CPX on the metastasis ability of NSCLC cells were analyzed by Transwell assays. Apoptosis assay was used to observe the level of cells apoptosis. The role of CPX in energy metabolism of NSCLC cells was investigated by reactive oxygen species (ROS) detection, glucose uptake, oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) experiments. Western blot was used to examine the protein changes.

Results

We report that CPX inhibits NSCLC cell migration and invasion abilities through inhibiting the epithelial-mesenchymal transition, impairing cellular bioenergetics, and promoting reactive oxygen species to activate endoplasmic reticulum (ER) stress-induced apoptotic cell death. Moreover, CPX intraperitoneal injection can significantly inhibit NSCLC growth in vivo in a xenograft model.

Conclusions

Our study revealed that CPX targets cellular bioenergetics and activates unfolded protein response in ER to drive apoptosis in NSCLC cells, indicating that CPX may be a potential therapeutic drug for the treatment of NSCLC.

Graphical Abstract

Breast intraductal nanoformulations for treating ductal carcinoma in situ II: Dose de-escalation using a slow releasing/slow bioconverting prodrug strategy

Ductal carcinoma in situ (DCIS) represents approximately 20-25% of newly diagnosed breast cancers. DCIS is treated by surgery and possibly radiotherapy. Chemotherapy is only used as adjuvant or neoadjuvant therapy but not as primary therapy. The present study investigated the intraductal administration of Ciclopirox (CPX) formulated in nanosuspensions (NSs) or nanoparticles (NPs) to treat DCIS locally in a Fischer 344 rat model orthotopically implanted with 13762 Mat B III cells. Slow converting esterase responsive CPX prodrugs (CPDs) were successfully synthesized at high purity (> 95%) by directly acetylating the hydroxyl group or by appending a self-immolative linker between CPX and a phenolic ester. Direct esterification CPDs were not sufficiently stable so self-immolative CPDs were formulated in NSs and NPs. Prodrug release was evaluated from poly(lactic-co-glycolic acid) NPs, and CPD4 demonstrated the slowest release rate with the rank order of CPD2 (R = methyl) > CPD3 (R = t-butyl) > CPD4 (R = phenyl). Intraductally administered CPX NS, CPD4 NS, and an innovative mixture of CDP4 NS and NPs (at 1 mg CPX equivalent/duct) demonstrated significant (p < 0.05) in vivo anti-tumor efficacy compared with immediate release (IR) CPX NS and non-treated controls. CPX mammary persistence at 6 h and 48 h after CPD4 NS or NP administration was also greater than after the immediate release CPX NS. A strong correlation between CPX mammary persistence and efficacy is demonstrated. In conclusion, nanoformulations utilizing a slow releasing/slow bioconverting CPX prodrug delivery strategy resulted in significant dose de-escalation (~ five fold) while maintaining anti-tumor efficacy.

Spread of Terbinafine-Resistant Trichophyton mentagrophytes Type VIII (India) in Germany-"The Tip of the Iceberg?"

Chronic recalcitrant dermatophytoses, due to Trichophyton (T.) mentagrophytes Type VIII are on the rise in India and are noteworthy for their predominance. It would not be wrong to assume that travel and migration would be responsible for the spread of T. mentagrophytes Type VIII from India, with many strains resistant to terbinafine, to other parts of the world. From September 2016 until March 2020, a total of 29 strains of T. mentagrophytes Type VIII (India) were isolated. All patients were residents of Germany: 12 females, 15 males and the gender of the remaining two was not assignable. Patients originated from India (11), Pakistan (two), Bangladesh (one), Iraq (two), Bahrain (one), Libya (one) and other unspecified countries (10). At least two patients were German-born residents. Most samples (21) were collected in 2019 and 2020. All 29 T. mentagrophytes isolates were sequenced (internal transcribed spacer (ITS) and translation elongation factor 1-α gene (TEF1-α)). All were identified as genotype VIII (India) of T. mentagrophytes. In vitro resistance testing revealed 13/29 strains (45%) to be terbinafine-resistant with minimum inhibitory concentration (MIC) breakpoints ≥0.2 µg/mL. The remaining 16 strains (55%) were terbinafine-sensitive. Point mutation analysis revealed that 10/13 resistant strains exhibited Phe³⁹⁷Leu amino acid substitution of squalene epoxidase (SQLE), indicative for in vitro resistance to terbinafine. Two resistant strains showed combined Phe³⁹⁷Leu and Ala⁴⁴⁸Thr amino acid substitutions, and one strain a single Leu³⁹³Phe amino acid substitution. Out of 16 terbinafine-sensitive strains, in eight Ala⁴⁴⁸Thr, and in one Ala⁴⁴⁸Thr +, new Val⁴⁴⁴ Ile amino acid substitutions were detected. Resistance to both itraconazole and voriconazole was observed in three out of 13 analyzed strains. Treatment included topical ciclopirox olamine plus topical miconazole or sertaconazole. Oral itraconazole 200 mg twice daily for four to eight weeks was found to be adequate. Terbinafine-resistant T. mentagrophytes Type VIII are being increasingly isolated. In Germany, transmission of T. mentagrophytes Type VIII from the Indian subcontinent to Europe should be viewed as a significant public health issue.

Ciclopirox Hydroxypropyl Chitosan (HPCH) Nail Lacquer: A Review of Its Use in Onychomycosis

Ciclopirox 8% hydroxypropyl chitosan (HPCH) [Marketed in different countries as the following registered (®) brands: Ciclopoli, Fulcare, Kitonail, Myconail, Niogermos, Niogermox, Onytec, Ony-Tec, Polinail, Privex, Rejuvenail] is the first topical nail lacquer developed using innovative drug formulation technology. It is indicated for the treatment of mild-to-moderate fungal infections of the nails that are caused by dermatophytes and/or other ciclopirox-sensitive fungi, without nail matrix involvement. HPCH is a patented drug formulation technology for the delivery of active principles into the nails based on a hydrosoluble semisynthetic amino-polysaccharide biopolymer derivative of chitosan. The lacquer acts as a protective barrier against microbiological attack, physical damage and/or aggressive chemicals. Results from in vitro studies suggest that the application of ciclopirox 8% HPCH nail lacquer improves drug permeation into and/or drug penetration through the nail, relative to the water-insoluble ciclopirox 8%, amorolfine 5% and efinaconazole 10% reference lacquers. In addition, in vitro and clinical studies in healthy subjects found that the concentration of ciclopirox reached in subungual fluids after application of ciclopirox 8% HPCH was sufficient for inhibiting fungal growth. In clinical studies in patients with mild-to-moderate onychomycosis, ciclopirox 8% HPCH was found to be more effective than the commercial water-insoluble ciclopirox 8% and amorolfine 5% lacquers, as indicated by higher complete cure, response and mycological cure rates at 48 weeks after treatment initiation. Ciclopirox 8% HPCH has been found to be generally well tolerated, with no treatment-related adverse events reported in patients using this nail lacquer. Thus, current evidence indicates that ciclopirox 8% HPCH represents a valuable treatment option for the treatment of patients with onychomycosis.

Breast intraductal nanoformulations for treating ductal carcinoma in situ I: Exploring metal-ion complexation to slow ciclopirox release, enhance mammary persistence and efficacy

INTRODUCTION

Ductal Carcinoma In Situ (DCIS) represents a significant fraction (~20-25%) of all newly diagnosed breast cancer cases and, if left untreated, a significant fraction of patients will progress to invasive disease. Surgery is the only treatment option. Ciclopirox (CPX), an FDA-approved antifungal drug, has exhibited promising antitumor activity by down-regulating the expression of vital antiapoptotic cellular proteins and inhibiting the genetic expression of several oncogenic pathways. In this study, the feasibility of using nanoscale delivery systems to control release and prolong mammary tissue persistence of a lipophilic metal complex of CPX and Zinc (CPXZn) after intraductal administration was investigated.

METHODS

CPX and CPX-Zn nanosuspensions (NSs) were prepared using an evaporative nanoprecipitation-ultra-sonication method. Flash nanoprecipitation was used to prepare PLGA nanoparticles (NPs) loaded with CPXZn. Our established orthotopic DCIS rat model was used to evaluate efficacy. Briefly, two days after 13762 Mat B III cell intraductal inoculation, rats were divided into treatment groups and a single intraductal injection of CPX NS, CPX-Zn NS or CPX-Zn NPs was administered. In the first study arm, the efficacy of CPX NS (1, 3, 5 mg/duct) was evaluated. In the second arm, the in vivo efficacy of CPX NS, CPX-Zn NS and CPX-Zn loaded NPs was evaluated and compared at equivalent CPX doses. The mammary persistence of CPX from CPX NS, CPX-Zn NS, and CPX-Zn PLGA NPs was also assessed.

RESULTS

CPX-Zn complex was successfully synthesized and characterized by several spectral analyses. CPX release was slowed from the CPX-Zn NS and further slowed by incorporating CPX-Zn into PLGA NPs as compared to the CPX NS with release half times following the order: CPX NS < CPX-Zn NS << CPX-Zn NP. Intraductal CPX NS administration was dose and time dependent in suppressing tumor initiation suggesting prolonged mammary exposure may improve efficacy. In the second arm, mammary tissue persistence of CPX followed the rank order CPX NS < CPX-Zn NS << CPX-Zn NP at 6 h and 48 h post-administration. Prolonged mammary CPX exposure was highly correlated to improved efficacy. Prolonged CPX tissue persistence, attributed to slower release from the zinc complex and the PLGA NPs, resulted in a 5-fold dose reduction compared to the CPX NS.

CONCLUSIONS

The current results demonstrate that slowing drug release in the mammary duct after intraductal administration overcomes the rapid ductal clearance of CPX, prolongs mammary tissue persistence, improves efficacy against DCIS lesions in vivo, and requires 5-fold less CPX to achieve equivalent efficacy. The studies also provide a strategic path forward for developing a locally administered drug delivery system for treating DCIS, for which no primary chemotherapy option is available.

Antifungal drug ciclopirox olamine reduces HSV-1 replication and disease in mice

Herpes simplex virus (HSV)-1 and HSV-2 cause painful blisters and shallow ulcers in exposed skin and mucosae during primary or recurrent infection. In addition, recurrent and potentially blinding HSV-1 infections of the eye afflict nearly half a million persons in the U.S. Current clinical therapies rely on nucleoside analog drugs such as acyclovir (ACV) or ganciclovir to ameliorate primary infections and reduce the frequency and duration of reactivations. However, these treatments do not fully suppress viral shedding and drug-resistant mutants develop in the eye and in vulnerable, immunosuppressed patients. Herpesvirus DNA replication requires several enzymes in the nucleotidyl transferase superfamily (NTS) that have recombinase and nuclease activities. We previously found that compounds which block NTS enzymes efficiently inhibit replication of HSV-1 and HSV-2 by up to 1 million-fold in Vero and human foreskin fibroblasts. Among the compounds with potent suppressive effects in culture is the anti-fungal drug ciclopirox. Here we report that topical application of ciclopirox olamine to the eyes of mice infected with HSV-1 reduced virus shed from the corneal epithelium compared with saline control, and reduced development of blepharitis to the level of mice treated with ACV. Results were dose-dependent. In addition, treatment with ciclopirox olamine significantly reduced acute and latent HSV-1 infection of the peripheral nervous system. These results support further development of ciclopirox olamine as a repurposed topical agent for HSV infections.

Microstructural alterations in the onychomycotic and psoriatic nail: Relevance in drug delivery

Despite the important nail alterations caused by onychomycosis and psoriasis few studies have characterized the microstructure of the diseased nail plate and the diffusion and penetration of drugs through this altered structure. This work aimed to characterize the microstructure of the healthy, onychomycotic and psoriatic human nail using Raman spectroscopy, scanning electron microscopy, optical microscope profilometry and mercury intrusion porosimetry followed by analysis of the structure with PoreCor® software. The results showed that onychomycotic nails have higher porosity and lower amounts of disulphide bonds compared to healthy nails. This suggests that the presence and action of fungi on the nail plate makes this structure more permeable to water and drugs. Psoriatic nails had increased porosity compared to healthy nails but lower than fungal infected specimens. In vitro permeation studies showed that diseased nails were more permeable to ciclopirox (onychomycosis) and clobetasol (psoriasis) although drug permeation was highly variable and likely to be influenced by the degree of alteration of the nail structure. On the whole, this work provides new and valuable information about the microstructure and porosity of diseased nails and a plausible explanation of the increased drug permeability observed in this work and elsewhere.

Role of acid responsive genes in the susceptibility of Escherichia coli to ciclopirox

Antibiotic resistance poses a huge threat to the effective treatment of bacterial infections. To circumvent the limitations in developing new antibiotics, researchers are attempting to repurpose pre-developed drugs that are known to be safe. Ciclopirox, an off-patent antifungal agent, inhibits the growth of Gram-negative bacteria, and genes involved in galactose metabolism and lipopolysaccharide (LPS) biosynthesis are plausible antibacterial targets for ciclopirox, since their expression levels partially increase susceptibility at restrictive concentrations. In the present study, to identify new target genes involved in the susceptibility of Escherichia coli to ciclopirox, genome-wide mRNA profiling was performed following ciclopirox addition at sublethal concentrations, and glutamate-dependent acid resistance (GDAR) genes were differentially regulated. Additional susceptibility testing, growth analyses and viability assays of GDAR regulatory genes revealed that down-regulation of evgS or hns strongly enhanced susceptibility to ciclopirox. Further microscopy and phenotypic analyses revealed that down-regulation of these genes increased cell size and decreased motility. Our findings could help to maximise the efficacy of ciclopirox against hard-to-treat Gram-negative pathogens.

Ciclopirox activates ATR-Chk1 signaling pathway leading to Cdc25A protein degradation

Ciclopirox olamine (CPX), an off-patent anti-fungal drug, has been found to inhibit the G1-cyclin dependent kinases partly by increasing the phosphorylation and degradation of Cdc25A. However, little is known about the molecular target(s) of CPX responsible for Cdc25A degradation. Here, we show that CPX induced the degradation of Cdc25A neither by increasing CK1α or decreasing DUB3 expression, nor via activating GSK3β, but through activating Chk1 in rhabdomyosarcoma (Rh30) and breast carcinoma (MDA-MB-231) cells. This is strongly supported by the findings that inhibition of Chk1 with TCS2312 or knockdown of Chk1 profoundly attenuated CPX-induced Cdc25A degradation in the cells. Furthermore, we observed that CPX caused DNA damage, which was independent of reactive oxygen species (ROS) induction, but related to iron chelation. CPX treatment resulted in the activation of ataxia telangiectasia mutated (ATM) and ATM-and RAD3-related (ATR) kinases. Treatment with Ku55933 (a selective ATM inhibitor) failed to prevent CPX-induced Chk1 phosphorylation and Cdc25A degradation. In contrast, knockdown of ATR conferred high resistance to CPX-induced Chk1 phosphorylation and Cdc25A degradation. Therefore, the results suggest that CPX-induced degradation of Cdc25A is attributed to the activation of ATR-Chk1 signaling pathway, a consequence of iron chelation-induced DNA damage.

Ciclopirox inhibits cancer cell proliferation by suppression of Cdc25A

Ciclopirox olamine (CPX), an off-patent fungicide, has recently been identified as a novel anticancer agent. However, the molecular mechanism underlying its anticancer action remains to be elucidated. Here we show that CPX inhibits cell proliferation in part by downregulating the protein level of Cdc25A in tumor cells. Our studies revealed that CPX did not significantly reduce Cdc25A mRNA level or Cdc25A protein synthesis, but remarkably promoted Cdc25A protein degradation. This resulted in inhibition of G₁-cyclin dependent kinases (CDKs), as evidenced by increased inhibitory phosphorylation of G₁-CDKs. Since Cdc25A degradation is tightly related to its phosphorylation status, we further examined whether CPX alters Cdc25A phosphorylation. The results showed that CPX treatment increased the phosphorylation of Cdc25A (S76 and S82), but only Cdc25A-S82A mutant was resistant to CPX-induced degradation. Furthermore, ectopic expression of Cdc25A-S82A partially conferred resistance to CPX inhibition of cell proliferation. Therefore, our findings indicate that CPX inhibits cell proliferation at least in part by promoting Cdc25A degradation.

Discovery of a novel series of N-hydroxypyridone derivatives protecting astrocytes against hydrogen peroxide-induced toxicity via improved mitochondrial functionality

Astrocytes play a key role in brain homeostasis, protecting neurons against neurotoxic stimuli such as oxidative stress. Therefore, the neuroprotective therapeutics that enhance astrocytic functionality has been regarded as a promising strategy to reduce brain damage. We previously reported that ciclopirox, a well-known antifungal N-hydroxypyridone compound, protects astrocytes from oxidative stress by enhancing mitochondrial function. Using the N-hydroxypyridone scaffold, we have synthesized a series of cytoprotective derivatives. Mitochondrial activity assay showed that N-hydroxypyridone derivatives with biphenyl group have comparable to better protective effects than ciclopirox in astrocytes exposed to H₂O₂. N-hydroxypyridone derivatives, especially 11g, inhibited H₂O₂-induced deterioration of mitochondrial membrane potential and oxygen consumption rate, and significantly improved cell viability of astrocytes. The results indicate that the N-hydroxypyridone motif can provide a novel cytoprotective scaffold for astrocytes via enhancing mitochondrial functionality.

Ciclopirox olamine inhibits mTORC1 signaling by activation of AMPK

Ciclopirox olamine (CPX), an off-patent antifungal agent, has recently been identified as a potential anticancer agent. The mammalian target of rapamycin (mTOR) is a central controller of cell growth, proliferation and survival. Little is known about whether and how CPX executes its anticancer action by inhibiting mTOR. Here we show that CPX inhibited the phosphorylation of p70 S6 kinase 1 (S6K1) and eukaryotic initiation factor 4E binding protein 1 (4E-BP1), two downstream effector molecules of mTOR complex 1 (mTORC1), in a spectrum of human tumor cells, indicating that CPX inhibits mTORC1 signaling. Using rhabdomyosarcoma cells as an experimental model, we found that expression of constitutively active mTOR (E2419K) conferred resistance to CPX inhibition of cell proliferation, suggesting that CPX inhibition of mTORC1 contributed to its anticancer effect. In line with this, treatment with CPX inhibited tumor growth and concurrently suppressed mTORC1 signaling in RD xenografts. Mechanistically, CPX inhibition of mTORC1 was neither via inhibition of IGF-I receptor or phosphoinositide 3-kinase (PI3K), nor by activation of phosphatase and tensin homolog (PTEN). Instead, CPX inhibition of mTORC1 was attributed to activation of AMP-activated protein kinase (AMPK)-tuberous sclerosis complexes (TSC)/raptor pathways. This is supported by the findings that CPX activated AMPK; inhibition of AMPK with Compound C or ectopic expression of dominant negative AMPKα partially prevented CPX from inhibiting mTORC1; silencing TSC2 attenuated CPX inhibition of mTORC1; and CPX also increased AMPK-mediated phosphorylation of raptor (S792). Therefore, the results indicate that CPX exerts the anticancer effect by activating AMPK, resulting in inhibition of mTORC1 signaling.

Development of ciclopirox nail lacquer with enhanced permeation and retention

Onychomycosis is a prevailing disease caused by fungal infection of nails that mostly affects athletes and the elderly. Ciclopirox is approved by the US Food and Drug Administration for the topical treatment of onychomycosis. However, the desired penetration of ciclopirox into the nail bed has not been achieved via topical application for efficient treatment. Therefore, the main aim of this study was to enhance ciclopirox permeation and retention in nail by the development of a new nail lacquer formulation. We screened the effects of different solvents, alkalizing agents, and permeation enhancers on the permeation of bovine hooves by ciclopirox and its retention in human nail clippings. The results suggest that isopropyl alcohol, potassium hydroxide, and urea as the solvent, alkalizing agent, and permeation enhancer, respectively, improved the permeation of the ciclopirox nail lacquer formulation the most with high flux rates. Comparison of the final formulation and marketed product revealed enhanced retention of ciclopirox from our developed formulation in human nail clippings. Therefore, our newly developed nail lacquer may be a potentially effective formulation for the treatment of onychomycosis in humans.

[Tinea pedis due to Fusarium solani in Dakar]

A patient presented with intertrigo at the second, third and fourth interdigitals spaces lasting for four years in which Fusarium solani was highlighted. The search for contributing factors revealed a concept of foot washing with water at least five times a day for ablutions, associated with wearing closed shoes all day and the absence of immunosuppression and diabetes. The diagnosis of Fusarium was made on the basis of direct examination and culture. Combined treatment with griseofulvin oral and topical ciclopirox was introduced and allowed healing after 45 days at which an antifungal powder was prescribed for relay. This case adds to the rare cases of intertrigo Fusarium sp. and confirms the frequent practice of ablutions as favoring factor.

Development of topical therapeutics for management of onychomycosis and other nail disorders: a pharmaceutical perspective

The human nail plate is a formidable barrier to drug permeation. Development of therapeutics for management of nail diseases thus remains a challenge. This article reviews the current knowledge and recent advances in the field of transungual drug delivery and provides guidance on development of topical/ungual therapeutics for management of nail diseases, with special emphasis on management of onychomycosis, the most common nail disease. Selection of drug candidates, drug delivery approaches, and evaluation of formulations are among the topics discussed. A comprehensive mathematical description for transungual permeation is also introduced.

Ciclopirox delivery into the human nail plate using novel lipid diffusion enhancers

CONTEXT

Onychomycosis is a common fungal infection of the nail plate and bed that affects up to 14% of the population and can have a substantial impact on the quality of life of those affected.

OBJECTIVE

This study compared the onychopharmacokinetics, nail absorption, nail distribution, and nail penetration of [(14)C]-ciclopirox dissolved in novel lipid diffusion enhancers with that of a commercial ciclopirox nail lacquer using the in vitro finite dose model.

MATERIALS AND METHODS

The penetration rate of ciclopirox was determined by applying doses of topical formulation twice daily to human nail plates for 11 d. Drug absorption was then measured by monitoring its rate of appearance in each nail layer and in the cotton pad/nail supporting bed.

RESULTS

After a multiple day treatment, cumulative concentrations of ciclopirox formulated with lipid enhancers in the deep nail layer and the nail bed were significantly greater than cumulative concentrations of the commercial ciclopirox lacquer (p < 0.001) as well as several orders of magnitude greater than the minimal inhibitory concentration (MIC) deemed necessary to inhibit the growth of the causative dermatophyte species.

CONCLUSION

When formulated with lipid enhancers, the amount of ciclopirox in the ventral/intermediate layer and supporting bed dramatically exceed the inhibitory concentration of ciclopirox for the most common onychomycosis organisms. These results suggest that topical ciclopirox with lipid enhancers has the potential to be an effective topical treatment for onychomycosis, and the lipidic pathway of the nail can be utilized as a means of effective transungual delivery.