Pharmacokinetics of antifungal agents in onychomycoses

Clinical Pharmacokinetics and Pharmacodynamics of Letermovir in Allogenic Hematopoietic Cell Transplantation

Letermovir is a newly developed antiviral agent used for the prophylaxis of human cytomegalovirus infections in patients undergoing allogeneic hematopoietic cell transplantation. This novel anti-cytomegalovirus drug, used for the prophylaxis of cytomegalovirus reactivation until approximately 200 days after transplantation, effectively reduces the risk of clinically significant cytomegalovirus infection. No human counterpart exists for the terminase complex; letermovir is virus specific and lacks some toxicities previously observed with other anti-cytomegalovirus drugs, such as cytopenia and nephrotoxicity. The absolute bioavailability of letermovir in healthy individuals is estimated to be 94% based on a population-pharmacokinetic analysis. In contrast, oral administration of letermovir to patients undergoing hematopoietic cell transplantation results in lower exposure than that in healthy individuals. Renal or hepatic impairment does not influence the intrinsic clearance of letermovir. Co-administration of letermovir may alter the plasma concentrations of other drugs, including itself, as it acts as a substrate and inhibitor/inducer of several drug-metabolizing enzymes and transporters. In particular, attention should be paid to the drug-drug interactions between letermovir and calcineurin inhibitors or azole antifungal agents, which are commonly used in patients undergoing hematopoietic cell transplantation. This article reviews and summarizes the clinical pharmacokinetics and pharmacodynamics of letermovir, focusing on patients undergoing hematopoietic cell transplantation, healthy individuals, and specific patient subsets.

Effectiveness and safety of oral terbinafine for dermatophyte distal subungual onychomycosis

INTRODUCTION

Terbinafine has been a cornerstone in dermatophyte infection treatment. Despite its global efficacy, the emergence of terbinafine resistance raises concerns, requiring ongoing vigilance.

AREAS COVERED

This paper focuses on evaluating the efficacy and safety of terbinafine in treating dermatophyte toenail infections. Continuous and pulse therapies, with a 24-week continuous regimen and a higher dosage of 500 mg/day have demonstrated superior efficacy to the FDA approved regimen of 250 mg/day x 12 weeks. Pulse therapies, though showing comparable effectiveness, present debates with regards to their efficacy as conflicting findings have been reported. Safety concerns encompass hepatotoxicity, gastrointestinal, cutaneous, neurologic, hematologic and immune adverse-effects, and possible drug interactions, suggesting the need for ongoing monitoring.

EXPERT OPINION

Terbinafine efficacy depends on dosage, duration, and resistance patterns. Continuous therapy for 24 weeks and a dosage of 500 mg/day may enhance outcomes, but safety considerations and resistance necessitate individualized approaches. Alternatives, including topical agents and alternative antifungals, are to be considered for resistant cases. Understanding the interplay between treatment parameters, adverse effects, and resistance mechanisms is critical for optimizing therapeutic efficacy while mitigating resistance risks. Patient education and adherence are vital for early detection and management of adverse effects and resistance, contributing to tailored and effective treatments.

Follow-up of Favipiravir-Induced Nail Fluorescence: Implications for Nail and Drugs

INTRODUCTION

Favipiravir creates fluorescence on nails, which can be seen with Wood's light.

OBJECTIVES

The objectives of this study are to examine the properties of fluorescence in the nail due to favipiravir and to observe whether other drugs also produce fluorescence in the nail.

METHODS

The research is descriptive, prospective, and quantitative. This study recruited 30 healthcare workers who received favipiravir treatment and 30 volunteers who took or did not take any medication except favipiravir from March 2021 to December 2021. Fingernails of the patients and control groups were examined under Wood's light in the darkroom. If fluorescence was observed in the fingernails, we followed up once a month until the fluorescence disappeared. We calculated the nail growth rate by dividing the distance of nail fluorescence from the proximal nail fold by the number of days since favipiravir was started.

RESULTS

We found nail fluorescence in all patients receiving a loading dose of favipiravir. The fluorescence in the nail decreased and disappeared in the 3rd month. The average nail growth rate at the first visit was 0.14 mm/day. The nail growth rate at the second visit was 0.10 mm/day. A statistically significant difference was found between the first and second visit nail growth rates (z: -2.576; p=0.010<0.05). We found that other drugs did not produce any fluorescence in the nail.

CONCLUSIONS

Nail fluorescence induced by favipiravir is dose-dependent and decreases in intensity over time. Nail fluorescence due to favipiravir is likely due to the active ingredient of the drug.

Updated Perspectives on the Diagnosis and Management of Onychomycosis

Onychomycosis is the most common nail disease encountered in clinical practice and can cause pain, difficulty with ambulation, and psycho-social problems. A thorough history and physical examination, including dermoscopy, should be performed for each patient presenting with nail findings suggestive of onychomycosis. Several approaches are available for definitive diagnostic testing, including potassium hydroxide and microscopy, fungal culture, histopathology, polymerase chain reaction, or a combination of techniques. Confirmatory testing should be performed for each patient prior to initiating any antifungal therapies. There are several different therapeutic options available, including oral and topical medications as well as device-based treatments. Oral antifungals are generally recommended for moderate to severe onychomycosis and have higher cure rates, while topical antifungals are recommended for mild to moderate disease and have more favorable safety profiles. Oral terbinafine, itraconazole, and griseofulvin and topical ciclopirox 8% nail lacquer, efinaconazole 10% solution, and tavaborole 5% solution are approved by the Food and Drug Administration for treatment of onychomycosis in the United States and amorolfine 5% nail lacquer is approved in Europe. Laser treatment is approved in the United States for temporary increases in clear nail, but clinical results are suboptimal. Oral fluconazole is not approved in the United States for onychomycosis treatment, but is frequently used off-label with good efficacy. Several novel oral, topical, and over-the-counter therapies are currently under investigation. Physicians should consider the disease severity, infecting pathogen, medication safety, efficacy and cost, and patient age, comorbidities, medication history, and likelihood of compliance when determining management plans. Onychomycosis is a chronic disease with high recurrence rates and patients should be counseled on an appropriate plan to minimize recurrence risk following effective antifungal therapy.

Onychomycosis in Patients with Diabetes Mellitus in Africa: A Global Scoping Review, 2000-2021

Onychomycosis is commonly studied in Africa but not in patients with diabetics despite having a significant number of her population living with diabetes mellitus (DM). Our review highlights a total of 15 studies with only two from Africa over the past two decades; 8 (53.3%) from Asia, 4 (26.7%) from Europe, 2 (13.3%) from Africa and 1 (6.7%) from North America. A total number of 4321 participants were involved with onychomycosis prevalence of 35.3% (1527/4321). Seven studies documented preponderance of onychomycosis in males, one showed preponderance in females, one showed no statistically significant difference in gender, while correlation with gender was unclear in the remainder. The risk factors identified were duration of diabetes, increasing age, occupation (agriculture), subclinical atherosclerosis, metabolic syndrome, obesity, triglyceride levels, and glycosylated haemoglobin. Three case control studies showed a statistically significant correlation between onychomycosis and individuals with DM. Diagnosis was mainly by microscopy and culture with Trichophyton (T) rubrum as the predominant isolate. Fungal nail infections are grossly underdiagnosed and/or underreported in Africa and hence the need for improved awareness and diagnosis especially in patients with DM. Although focused on Africa, this study also revealed paucity of data on onychomycosis in diabetic patients living in the Americas despite evidence from the literature showing a significant number of individuals from that region are living with diabetes. The need to evaluate this at-risk population for onychomycosis cannot be over emphasized.

Risk of fetal malformation, spontaneous abortion, and adverse pregnancy outcomes after gestational terbinafine exposure: a systematic review

Fungal skin and nail infections are common health issues affecting an estimated 10%-20% of the world's population. The antifungal agent terbinafine shows broad-spectrum activity against a wide range of fungal species and is commonly prescribed as a first-line treatment for dermatomycoses and onychomycoses. However, owing to insufficient data regarding embryotoxicity and adverse pregnancy outcomes, treatment with terbinafine is currently not recommended in pregnancy and breastfeeding. This systematic review aimed to evaluate the effects of gestational terbinafine exposure on congenital malformations, spontaneous abortions, and adverse pregnancy outcomes. PubMed/MEDLINE, EMBASE, and clinicaltrials.org were searched to retrieve relevant reports up to March 2022. Two investigators independently screened the articles, extracted the data, and performed a quality assessment using the Newcastle-Ottawa Scale. Two cohort and two case-control studies were eligible for inclusion. Overall, the study showed the absence of an increased risk of congenital malformations, spontaneous abortion, preterm birth, small for gestational age, low birth weight, or stillbirth, following systemic or topical terbinafine exposure during pregnancy. In conclusion, the use of systemic and topical terbinafine during pregnancy can be regarded as safe for mothers and unborn children. The current recommendation concerning gestational terbinafine administration should be reconsidered.

Formulation and Characterization of Chitosan-Decorated Multiple Nanoemulsion for Topical Delivery In Vitro and Ex Vivo

In the present study, chitosan-decorated multiple nanoemulsion (MNE) was formulated using a two-step emulsification process. The formulated multiple nanoemuslion was evaluated physiochemically for its size and zeta potential, surface morphology, creaming and cracking, viscosity and pH. A Franz diffusion cell apparatus was used to carry out in vitro drug-release and permeation studies. The formulated nanoemulsion showed uniform droplet size and zeta potential. The pH and viscosity of the formulated emulsion were in the range of and suitable for topical delivery. The drug contents of the simple nanoemulsion (SNE), the chitosan-decorated nanoemulsion (CNE) and the MNE were 71 ± 2%, 82 ± 2% and 90 ± 2%, respectively. The formulated MNE showed controlled release of itraconazole as compared with that of the SNE and CNE. This was attributed to the chitosan decoration as well as to formulating multiple emulsions. The significant permeation and skin drug retention profile of the MNE were attributed to using the surfactants tween 80 and span 20 and the co-surfactant PEG 400. ATR-FTIR analysis confirmed that the MNE mainly affects the lipids and proteins of the skin, particularly the stratum corneum, which results in significantly higher permeation and retention of the drug. It was concluded that the proposed MNE formulation delivers drug to the target site of the skin and can be therapeutically used for various cutaneous fungal infections.

A Novel Itraconazole Pulse Therapy Schedule in the Treatment of Tinea Capitis in Children

Tinea capitis is a common dermatophytosis predominantly occurring in children, which needs oral antifungal drug therapy. Itraconazole pulse therapy has been widely applicated in the treatment of adult onychomycosis. However, only a few studies are available for the treatment of pediatric tinea capitis with itraconazole pulse therapy. The therapy schedules vary with respect to dose and intermission. Here, we report four cases of tinea capitis that were treated with a novel high-dose itraconazole pulse therapy (6–10 mg/kg/d with 3 weeks off between consecutive pulses). After 2–3 pulses therapy, all the patients were cured and no adverse reactions were observed. We demonstrate the efficacy and safety of this novel itraconazole pulse therapy schedule. It may be a promising therapy in the treatment of tinea capitis in children.

Preparation of Topical Itraconazole with Enhanced Skin/Nail Permeability and In Vivo Antifungal Efficacy against Superficial Mycosis

In this study, a stable and highly skin-permeable topical delivery system for itraconazole (ITZ) was designed to provide effective treatment against superficial mycosis. Herein, ITZ was incorporated into a solution composed of ethanol, benzyl alcohol, hydrochloric acid, Transcutol P, and cyclomethicone as a delivery vehicle, solubilizer, protonating agent, permeation enhancer, and spreading agent, respectively. At 72 h, the optimal topical ITZ formulation (ITZ–TF#11) exhibited 135% enhanced skin permeability, which led to increases in drug deposition in the stratum corneum, epidermis, and dermis of 479%, 739%, and 2024%, respectively, compared with the deposition of 1% ITZ in ethanol (control). Moreover, on day 7, ITZ–TF#11 demonstrated 2.09- and 2.30-fold enhanced nail flux and drug deposition, compared with the control. At a dose of 40 mg/kg/day, ITZ–TF#11 showed 323% greater lesion recovery, a 165% lower mean erythema severity score, and a 37% lower mean logarithm of viable fungal cells in skin in the treated area, compared with mice that received oral ITZ at the same dose. Overall, the findings imply that ITZ–TF#11 is a superior alternative to oral ITZ for treatment of superficial mycosis.

In Vitro Combination Effect of Topical and Oral Anti-Onychomycosis Drugs on Trichophyton rubrum and Trichophyton interdigitale

To evaluate the combination effects of anti-onychomycosis drugs, the minimum inhibitory concentrations of topical (efinaconazole, luliconazole, and tavaborole) and oral (itraconazole and terbinafine) drugs for Trichophyton rubrum and Trichophyton interdigitale (8 each, with a total of 16 strains) were determined using the microdilution checkerboard technique based on the Clinical and Laboratory Standard Institute guidelines. No antagonism was observed between the topical and oral drugs against all the tested strains. Efinaconazole with terbinafine exerted a synergistic effect on 43.8% of the strains tested (7/16 strains) and efinaconazole with itraconazole on 12.5% (2/16 strains). Conversely, luliconazole showed no synergistic effect with terbinafine but was synergistically effective with itraconazole against 31.3% of the strains (5/16 strains). Tavaborole showed no synergistic effect with terbinafine and was synergistically effective with itraconazole against 18.8% of the strains (3/16 strains). The results suggest that a combination of topical and oral drugs could be a potential clinical option for onychomycosis treatment, and overall, the efinaconazole and oral drug combination would be the most advantageous among the tested combinations.

Evaluation of Association Between Oral and Topical Terbinafine Use in Pregnancy and Risk of Major Malformations and Spontaneous Abortion

Importance

Terbinafine is a commonly used antifungal agent, but safety data of its use in pregnancy are limited.

Objective

To examine the association between oral and topical terbinafine exposure in pregnancy and the risk of major malformations and spontaneous abortion.

Design, Setting, and Participants

A nationwide, registry-based cohort study was conducted in Denmark from January 1, 1997, to December 31, 2016, in a cohort of 1 650 649 pregnancies. Data analysis was performed from July 11 to October 20, 2019. Pregnancies were matched on propensity scores comparing oral terbinafine exposed vs unexposed (1:10 ratio), topical terbinafine exposed vs unexposed (1:10), and oral vs topical terbinafine exposed (1:1).

Exposures

Filled prescriptions for oral or topical terbinafine.

Main Outcomes and Measures

Logistic regression was used to compute prevalence odds ratios for the primary outcome of major malformations and Cox proportional hazards regression was used to compute hazard ratios for the secondary outcome of spontaneous abortion.

Results

Based on a cohort of 1 650 649 pregnancies, oral terbinafine-exposed (n = 891 pregnancies; mean [SD] age, 30.4 [6] years) and topical terbinafine-exposed (n = 3174; mean [SD] age, 29.5 [5.4] years) pregnancies were identified; up to a total of 40 650 unexposed pregnancies were included for the matched outcome analyses. In propensity-matched comparisons of the risk of major malformations, the prevalence odds ratios were 1.01 (95% CI, 0.63-1.62) for oral terbinafine-exposed vs unexposed pregnancies (absolute risk difference [ARD], 0.04%; 95% CI, -1.69% to 1.76%), 1.08 (95% CI, 0.81-1.44) for topical terbinafine-exposed vs unexposed pregnancies (ARD, 0.26%; 95% CI, -0.73% to 1.26%), and 1.18 (95% CI, 0.61-2.29) for oral vs topical terbinafine-exposed pregnancies (ARD, 0.59%; 95% CI, -1.71% to 2.88%). For the risk of spontaneous abortion, the hazard ratios were 1.06 (95% CI, 0.86-1.32) for oral terbinafine-exposed vs unexposed pregnancies (ARD, 0.13%; 95% CI, -1.97% to 2.24%), 1.04 (95% CI, 0.88-1.21) for topical terbinafine-exposed vs unexposed pregnancies (ARD, 0.17%; 95% CI, -0.64% to 0.98%), and 1.19 (95% CI, 0.84-1.70) for oral vs topical terbinafine-exposed (ARD, 1.13%; 95% CI, -2.23% to 4.50%) pregnancies.

Conclusions and Relevance

Among pregnancies exposed to oral or topical terbinafine, no increased risk of major malformations or spontaneous abortion was identified.

Assessment of Pharmacokinetic Interaction Between Letermovir and Fluconazole in Healthy Participants

Letermovir is a prophylactic agent for cytomegalovirus infection and disease in adult cytomegalovirus-seropositive recipients of allogeneic hematopoietic stem cell transplant. As the antifungal agent fluconazole is administered frequently in transplant recipients, a drug-drug interaction study was conducted between oral letermovir and oral fluconazole. A phase 1 open-label, fixed-sequence study was performed in healthy females (N = 14, 19-55 years). In Period 1, a single dose of fluconazole 400 mg was administered. Following a 14-day washout, a single dose of letermovir 480 mg was administered (Period 2), and after a 7-day washout, single doses of fluconazole 400 mg and letermovir 480 mg were coadministered in Period 3. Pharmacokinetics and safety were evaluated. The pharmacokinetics of fluconazole and letermovir were not meaningfully changed following coadministration. Fluconazole geometric mean ratio (GMR; 90% confidence interval [CI]) with letermovir for area under the concentration-versus-time curve from time 0 to infinity (AUC_0-∞ ) was 1.03 (0.99-1.08); maximum concentration (C_max ) was 0.95 (0.92-0.99). Letermovir AUC_0-∞ GMR (90%CI) was 1.11 (1.01-1.23), and C_max was 1.06 (0.93-1.21) following coadministration with fluconazole. Coadministration of fluconazole and letermovir was generally well tolerated.

Oral antifungal therapies for toenail onychomycosis: a systematic review with network meta-analysis toenail mycosis: network meta-analysis

Aim: Toenail fungal infections account for half of all nail disease cases, and a highly negative impact on patient quality of life. Our aim was to compare the efficacy and safety of commercially available oral antifungals for onychomycosis.Methods: A systematic review was performed in PubMed and Scopus. Randomized controlled trials evaluating the effect of oral antifungals on mycological cure, discontinuation and adverse events were included. Network meta-analyses were built for each outcome. Results were reported as odds ratios (OR) with 95% credibility intervals (CrI). Ranking probabilities were calculated by surface under the cumulative ranking analysis (SUCRA).Results: We included 40 trials (n = 9568). Albaconazole 400 mg (OR 0.02 [95% CrI 0.01-0.07] versus placebo), followed by posaconazole 200-400 mg and terbinafine 250-350 mg were considered the best therapies (SUCRA probabilities over 75%). For the networks of discontinuation and individual adverse events, few significant differences among treatments were observed, but itraconazole 400 mg was considered the safest drug (SUCRA around 25%). Albaconazole 400 mg, posaconazole 200-400 mg, and terbinafine 250-350 mg were the most effective therapies for onychomycosis, while itraconazole 400 mg was the safest.Conclusion: The profile of albaconazole and posaconazole compared to current first-line therapies should be further investigated in well-designed trials.

Defining breakthrough invasive fungal infection-Position paper of the mycoses study group education and research consortium and the European Confederation of Medical Mycology

Breakthrough invasive fungal infections (IFIs) have emerged as a significant problem in patients receiving systemic antifungals; however, consensus criteria for defining breakthrough IFI are missing. This position paper establishes broadly applicable definitions of breakthrough IFI for clinical research. Representatives of the Mycoses Study Group Education and Research Consortium (MSG-ERC) and the European Confederation of Medical Mycology (ECMM) reviewed the relevant English literature for definitions applied and published through 2018. A draft proposal for definitions was developed and circulated to all members of the two organisations for comment and suggestions. The authors addressed comments received and circulated the updated document for approval. Breakthrough IFI was defined as any IFI occurring during exposure to an antifungal drug, including fungi outside the spectrum of activity of an antifungal. The time of breakthrough IFI was defined as the first attributable clinical sign or symptom, mycological finding or radiological feature. The period defining breakthrough IFI depends on pharmacokinetic properties and extends at least until one dosing interval after drug discontinuation. Persistent IFI describes IFI that is unchanged/stable since treatment initiation with ongoing need for antifungal therapy. It is distinct from refractory IFI, defined as progression of disease and therefore similar to non-response to treatment. Relapsed IFI occurs after treatment and is caused by the same pathogen at the same site, although dissemination can occur. These proposed definitions are intended to support the design of future clinical trials and epidemiological research in clinical mycology, with the ultimate goal of increasing the comparability of clinical trial results.

Characteristics of Skin Deposition of Itraconazole Solubilized in Cream Formulation

Itraconazole (ITZ) is an anti-fungal agent generally used to treat cutaneous mycoses. For efficient delivery of ITZ to the skin tissues, an oil-in-water (O/W) cream formulation was developed. The O/W cream base was designed based on the solubility measurement of ITZ in various excipients. A physical mixture of the O/W cream base and ITZ was also prepared as a control formulation to evaluate the effects of the solubilized state of ITZ in cream base on the in vitro skin deposition behavior of ITZ. Polarized light microscopy and differential scanning calorimetry demonstrated that ITZ was fully solubilized in the O/W cream formulation. The O/W cream formulation exhibited considerably enhanced deposition of ITZ in the stratum corneum, epidermis, and dermis compared with that of the physical mixture, largely owing to its high solubilization capacity for ITZ. Therefore, the O/W cream formulation of ITZ developed in this study is promising for the treatment of cutaneous mycoses caused by fungi such as dermatophytes and yeasts.

Recent Patents on Permeation Enhancers for Drug Delivery Through Nails

The human nail is a unique barrier with a keratinized constitution that favors protection and fine touch. However, many disorders can affect the nail, among them, are the onychomycosis and psoriasis. Systemic oral therapy has been applied to treat these diseases, even presenting disadvantages, including side effects, drug interactions, contraindications, toxicity, high cost and low patient compliance. A great option to succeed in dealing with the problems associated with oral therapy is the topical administration of drugs. However, nail composition, low diffusion through ungual route and reduced tissue bioavailability for topical treatments are limiting factors. These drawbacks can be overcome by promoting penetration through the nails by employing penetration enhancers. The review focuses on patents that highlight permeation enhancers applied to nail drug delivery for the treatment of onychomycosis and psoriasis. Literature and patent searches were conduced regarding the topic of interest. The substantial literature and patent search revealed that permeation enhancers, especially chemicals, are great strategies for promoting the ungual delivery of drugs. Nail topical therapy containing permeation enhancers is an attractive option for delivering localized treatments.

Terbinafine Hydrochloride Trans-ungual Delivery via Nanovesicular Systems: In Vitro Characterization and Ex Vivo Evaluation

Treating a nail infection like onychomycosis is challenging as the human nail plate acts as a formidable barrier against all drug permeation. Available oral and topical treatments have several setbacks. Terbinafine hydrochloride (TBH), belonging to the allylamine class, is mainly used for treatment of onychomycosis. This study aims to formulate TBH in a nanobased spanlastic vesicular carrier that enables and enhances the drug delivery through the nail. The nanovesicles were formulated by ethanol injection method, using either Span® 60 or Span® 65, together with Tween 80 or sodium deoxycholate as an edge activator. A full factorial design was implemented to study the effect of different formulation and process variables on the prepared TBH-loaded spanlastic nanovesicles. TBH entrapment efficiency percentages, particle size diameter, percentage drug released after 2 h and 8 h were selected as dependent variables. Optimization was performed using Design-Expert® software to obtain an optimized formulation with high entrapment efficiency (62.35 ± 8.91%), average particle size of 438.45 ± 70.5 nm, and 29.57 ± 0.93 and 59.53 ± 1.73% TBH released after 2 and 8 h, respectively. The optimized formula was evaluated using differential scanning calorimetry and X-ray diffraction and was also morphologically examined using transmission electron microscopy. An ex vivo study was conducted to determine the permeation and retainment of the optimized formulation in a human cadaver nail plate, and confocal laser scanning microscope was used to show the extent of formulation permeation. In conclusion, the results confirmed that spanlastics exhibit promising results for the trans-ungual delivery of TBH.

Management of Onychomycosis in Canada in 2014

Background

Onychomycosis has several clinical presentations and is caused by various infectious organisms.

Objective

To provide guidance for selection of appropriate treatment.

Methods

The literature on onychomycosis management was reviewed to generate an evidence-based decision tree.

Results and Conclusion

Several options are available: terbinafine, itraconazole, fluconazole, ciclopirox 8% nail lacquer, efinaconazole 10% nail solution, and laser therapy. Further studies on lasers are needed before use can be recommended. Nondermatophyte molds or mixed infection can be managed with terbinafine or itraconazole with or without topicals. Itraconazole, fluconazole, and efinaconazole can be used for Candida infection. For dermatophytes, topicals can be considered for mild to moderate onychomycosis. For moderate to severe cases, any oral monotherapy can be used; however, we suggest terbinafine if there is a possibility of a drug interaction. These recommendations can be applied for all ages, immune function, or metabolic status, but proper monitoring and contraindications should be taken into consideration.

Clinical and Pharmacokinetic Studies of Continuous Itraconazole for the Treatment of Onychomycosis

Itraconazole, a triazole antifungal agent, has been widely used for onychomycosis with high cure rates. Unchanged itraconazole and a major metabolite hydroxy-itraconazole reach the nail with a strong affinity for keratin. The aim of this study was to elucidate clinical effectiveness and pharmacokinetic profiles of a 6-month continuous itraconazole treatment at a daily dose of 100 mg. Nail growth, the decrease in nail turbidity, and the nail concentrations of unchanged- and hydroxy-itraconazole were investigated. The affected nails we examined demonstrated nail growth proportional to the decrease in turbidity and a quick increase in drug concentration with a long duration of a high concentration after cessation. Our results support the hypothesis that this continuous therapy is a good modality for onychomycosis.

Novel topical formulations of Terbinafine-HCl for treatment of onychomycosis

Terbinafine hydrochloride (TBF-HCl) is an active substance that is using for treatment of onychomycosis. Onychomycosis is a fungal infection which is the most common disease of nail plate. The nail plate is a barrier which prevents effective topical treatment of ungual disorders. In this study, TBF-HCl loaded liposome and ethosome formulations and also gel form of these formulations were prepared. The formulations were characterized and in vitro and ex vivo release studies were performed. Nail characterization studies were also performed to examine the effect of formulations and experimental conditions on nail surface. As a result, all formulations can serve as efficient formulations for ungual application of TBF-HCl. By the way, the results of the accumulation studies suggested that liposome poloxamer gel formulation could be promising system for ungual drug delivery due to the better accumulation and easier application of the formulation.

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.

Pharmacokinetics of orally administered terbinafine in African penguins (Spheniscus demersus) for potential treatment of aspergillosis

The objective of this study was to determine the pharmacokinetic parameters of orally administered terbinafine hydrochloride based on 3, 7, and 15 mg/kg single- as well as multiple-dosage trials in order to calculate dosing requirements for potential treatment of aspergillosis in African penguins (Spheniscus demersus). Ten adult African penguins were used in each of these trials, with a 2-wk washout period between trials. Mean plasma concentrations of terbinafine peaked in approximately 4 hrs at 0.11 +/- 0.017 microg/ml (mean +/- SD) following administration of 3 mg/kg terbinafine, while 7 mg/kg and 15 mg/kg dosages resulted in peak plasma concentrations of 0.37 +/- 0.105 and 0.33 +/- 0.054 microg/ml, respectively. The volume of distribution increased with increasing dosages, being 37 +/- 28.5, 40 +/- 28.1, and 52 +/- 18.6 mg/L for 3, 7, and 15 mg/kg doses, respectively. The mean half-life was biphasic with initial terminal half-life (t(1/2)) values of 9.9 +/- 4.5, 17.2 +/- 4.9 and 16.9 +/- 5.4 hrs, for 3, 7, and 15 mg/kg doses, respectively. A rapid first elimination phase was followed by a slower second phase, and final elimination was estimated to be 136 +/- 9.7 and 131 +/- 9.9 hrs, for 7 and 15 mg/kg doses, respectively. Linearity was demonstrated for area under the curve but not for peak plasma concentrations for the three dosages used. Calculations based on pharmacokinetic parameter values indicate that a 15 mg/kg terbinafine q24h dosage regimen would result in steady-state trough plasma concentrations above the minimum inhibitory concentration (0.8-1.6 microg/ ml), and this dosage is recommended as a potential treatment option for aspergillosis in penguins. However, additional research is required to determine both treatment efficacy and safety.

In vitro activity of Tachyplesin III alone and in combination with terbinafine against clinical isolates of dermatophytes

Aim of our study was to investigate the in vitro effects of Tachyplesin III (TP), a potent disulfide-linked peptide, in dermatophytes infections, with respect to or in combination with terbinafine (TERB), against 20 clinical isolates of dermatophytes belonging to four species. A broth microdilution method following the CLSI recommendations (M38-A) was used for testing drugs alone and in combination. TERB MICs were significantly lower than those observed for TP (p<0.001). Testing for antifungal agents in combination was performed for TERB with TP for all the 20 isolates. TERB activity in combination with TP showed indifferent activity for 14 of the 20 isolates (70%); synergic activity for 6 of the 20 isolates (30%); no antagonistic activity was observed. Further experiments were conducted with Microsporum canis 133, Trichophyton rubrum 62 and Trichophyton mentagrophytes 91 for fungal biomass. TP and TERB did not show a significant growth reduction compared to the control against T. mentagrophytes and T. rubrum. A significant difference of growth reduction both for TP and TERB compared to controls was observed for M. canis (p<0.01). In conclusion our study demonstrated that Tachyplesin III has potential activity against dermatophytes. In addition, we observed that the in vitro activity of Tachyplesin III can be enhanced upon combination with terbinafine. Synergy could permit lower doses of the individual antifungal agents to be used more effectively and/or safely.

Efficacy of Fluconazole for the Treatment of Onychomycosis

Objective:

To evaluate the efficacy of fluconazole for the treatment of onychomycosis.

Data Sources:

Searches of MEDLINE (1966–May 2009) and International Pharmaceutical Abstracts (1970–May 2009) were performed. Key search terms included fluconazole and onychomycosis. In addition, reference citations from identified publications were reviewed.

Study Selection and Data Extraction:

All articles in English identified from the data sources were evaluated. All studies evaluating oral fluconazole for the treatment of onychomycosis were included in the review.

Data Synthesis:

Seven studies evaluating fluconazole treatment for onychomycosis were identified. One study used daily dosing and the rest used once-weekly dosing. Treatment doses ranged from 100 mg to 450 mg weekly and 150 mg daily, and durations ranged from 12 weeks to 12 months. Most of the studies evaluated the efficacy of fluconazole in patients with toenail onychomycosis due to dermatophyte infection. Fluconazole was superior to placebo, with mycologic eradication rates ranging from 36% to 100% in placebo-controlled studies. In one of the comparative studies, the mycologic cure rate was lower with fluconazole (31.2%) compared with terbinafine (75%) and itraconazole (61.1%). Common adverse events reported with fluconazole use were headache, gastrointestinal pain, and diarrhea.

Conclusions:

Fluconazole is less effective than terbinafine and itraconazole in the treatment of onychomycosis. However, fluconazole may be preferred in patients unable to tolerate other oral antifungal agents due to the dosing regimen, adverse effect profile, and drug interactions.

Two novel itraconazole pulse therapies for onychomycosis: A 2‐year follow‐up

BACKGROUND

Itraconazole given in pulse therapy has become popular for onychomycosis treatment since it results in less plasma exposure to the drug while maintaining an effective drug concentration in the nail plate and also increasing patient compliance.

OBJECTIVE

The current study aims to evaluate two different regimens of itraconazole for toenail onychomycosis, looking at both the immediate post-therapy cure rate and the relapse rate after 2 years.

METHODS

Two groups of 52 patients each were given either 'standard' oral itraconazole pulse therapy for 3 months (200 mg x 2/day for 1 week/month) followed by an additional single course (200 mg/day for 7 days) after 3 months (regimen A) or 'modified' (6-week interval) itraconazole pulse therapy x3 followed by an additional single course (200 mg x 2/day for 7 days) after 3 months. All patients were followed-up for 24 months from the beginning of treatment.

RESULTS

Regimen A: 37 patients were available for examination after 24 months, of whom 22 patients (59.5%) had total cure and two patients (5.5%) had marked improvement. Regimen B: 38 patients were available for examination after 24 months, of whom 29 patients (76.3%) had total cure and three patients (7.9%) had marked improvement. There were no statistical differences in cure rates between the two groups at the end of treatment, after 12 months and after 24 months. None of the patients (in both treatment groups) who had total cure at the end of the treatment period had onychomycosis recurrence after 12 or 24 months.

CONCLUSION

The results at the end of the 24-month period are encouraging, where 64.9% (regimen A) and 84.2% (regimen B) of the patients had total cure or marked improvement in their toenail condition. Therefore, those two regimens are acceptable alternatives to the current treatment regimen.

Combination therapy consisting of week pulses of oral terbinafine plus topical application of terbinafine cream in the treatment of onychomycosis

BACKGROUND

Terbinafine, based on its pharmacokinetic properties, is a good candidate for pulse therapy. There are, as yet, no current guidelines for a terbinafine 1-week pulse regimine.

OBJECTIVE

To determine the optimal 1-week pulse dosing regimen for combination therapy of oral terbinafine with complementary 1% terbinafine cream for the treatment of onychomycosis.

DESIGN

A total of 69 onychomycosis patients received 250 mg terbinafine, given orally once daily for 7 days as 1-week pulses, separated by intervals of 2-3 weeks, until the desired improvement was observed. A daily application of 1% terbinafine cream was advised through to the evaluation date at 12 months follow-up. The treatment regimens were compared based on the number of pulses and the duration of treatment.

RESULTS

The 45 patients (65.2%) who achieved complete cure received an average of 7.8+/-3.5 pulse treatments over 4.8+/-2.6 months. The optimal terbinafine dosing regimen consisted of alternate 1-week pulses, with most patients on this regimen (19/20 cases; 95%) achieving total cure.

CONCLUSION

Favorable treatment outcome was gained from this terbinafine 1-week pulse regimen and also better compliance compared with a standard daily regimen.

Pulsed versus continuous terbinafine dosing in the treatment of dermatophyte onychomycosis

BACKGROUND

The accepted regimen for terbinafine, one of the most effective treatments for dermatophyte onychomycosis, is continuous administration of 250 mg/day over 16 weeks. A few small studies, however, have raised the possibility of an alternative regimen: pulsed administration of 500 mg/day for 1 week, every 4 weeks (over 16 weeks), without decreasing treatment efficacy.

OBJECTIVE

Our aim was to compare the efficacy and safety of both regimens in a large group of patients.

METHODS

Retrospective analysis of 260 patients with culture proven dermatophyte onychomycosis treated in seven outpatient clinics run by two dermatologists using one of the terbinafine protocols on a chronological basis: 105 patients were treated using the continuous regimen during 1998/1999 and 155 patients were treated using the pulsed regimen during 1999/2002. Mycological and clinical cure were assessed 2 and 3 months, respectively, after completion of the last therapeutic course. Side effects were documented for the pulse regimen group only and compared with historical data previously published for the continuous protocol.

RESULTS

The mycological, clinical and complete (mycological and clinical) cure rates of the toenails were 72.1%, 53.5% and 47.1% in the pulse regimen versus 82%, 35% and 34% in the continuous regimen, respectively (p=0.091, 0.0002 and 0.047, respectively). The mycological, clinical and complete cure rates of the fingernails were 91.7%, 83.3% and 79.2% respectively in the pulse group versus 100% (all parameters) in the continuous group (no significant difference). In general, both regimens were well tolerated and few side effects were reported.

CONCLUSION

The pulsed regimen is at least as effective as continuous dosing and thus, at 50% less cost and more convenience, is preferable to a continuous regimen.

In vitro activities of miltefosine and two novel antifungal biscationic salts against a panel of 77 dermatophytes

The susceptibilities of 77 dermatophytes to miltefosine (MI), 1,12-bis(4-pentylpyridinium)dodecane (PYR), 1,12-bis(tributylammonium)dodecane (AM), itraconazole (ITC), terbinafine (TRB), and butenafine (BTF) were compared. Geometric mean MICs of TRB, BTF, ITC, MI, PYR, and AM were 0.039, 0.059, 1.718, 0.671, 6.006, and 4.771 microg/ml, respectively. MI was more active than ITC (P < 0.001).

Iontophoretic Drug Delivery across Human Nail

Topical trans-nail delivery of antifungal drugs is limited by several physicochemical and physiological factors. Use of chemical permeation enhancers has been a common approach for enhancing trans-nail delivery of drugs. The potential of physical permeation enhancement techniques has been found to be higher than the potential of chemical permeation enhancers in transdermal delivery of hydrophilic drugs and macromolecular therapeutic agents. However, application of physical permeation enhancement techniques has not been explored for trans-nail drug delivery. In the current work, iontophoresis was applied across human nail in vitro to assess its efficiency in enhancing drug delivery. Salicylic acid (SA) was used as test diffusant. The influence of pH, ionic strength, and current density was studied. Obviously, increase in current density increased the trans-nail transport flux. It appears that about 50-100 mM ionic strength is required for optimal conduction of electric current across nail. The flux enhancement factor (iontophoretic flux/passive flux) also increased with increase in pH due to increased ionization of SA. This study demonstrates the efficacy of iontophoresis in enhancing the trans-nail delivery of drugs.

Co-prescriptions with itraconazole and fluconazole as a signal for possible risk of drug–drug interactions: a four-year analysis from Italian general practice

PURPOSE

To determine the prevalence of concomitant use of drugs potentially responsible for interactions among itraconazole and fluconazole users in general practice.

METHODS

During the years 1999-2002, we obtained information from the 'Health Search Database', (HSD) an Italian general practice research database. Among a total sample of 457 672 eligible patients, we included those aged >16 years, and whose diagnoses could be classified as mycosis. Itraconazole and fluconazole users were then selected. A potentially drug-drug interaction (DDI) occurred when the use of concomitant drugs were recorded within +/-30 days from the date of the first azoles prescription. Interacting drugs were classified according to the summary of product characteristics (SPC) as provided by the Italian Pharmaceutical Repertory (REFI).

RESULTS

From 18 323 cases of mycosis, we selected 4843 itraconazole and 1446 fluconazole users. Potentially interacting drugs were prescribed in 8.7% of itraconazole and 6.1% of fluconazole users. For itraconazole, calcium channel blockers were the most common interacting drugs (3.3%), followed by statins (1.7%) and clarithromycin (1.3%), whereas gestoden + ethynylestradiol (2.5%) and benzodiazepines (1.8%) resulted as the most common interacting drugs among fluconazole users.

CONCLUSION

Data indicate a relevant prevalence of concomitant use of medications potentially leading to drug interactions among azoles users. Because of the wide use of these medications in general practice, they should be used with clinical monitoring in view of their known side effects as well as their potential risk for drug interaction.

Human pharmacogenomic variations and their implications for antifungal efficacy

Pharmacogenomics is defined as the study of the impacts of heritable traits on pharmacology and toxicology. Candidate genes with potential pharmacogenomic importance include drug transporters involved in absorption and excretion, phase I enzymes (e.g., cytochrome P450-dependent mixed-function oxidases) and phase II enzymes (e.g., glucuronosyltransferases) contributing to metabolism, and those molecules (e.g., albumin, A1-acid glycoprotein, and lipoproteins) involved in the distribution of antifungal compounds. By using the tools of population genetics to define interindividual differences in drug absorption, distribution, metabolism, and excretion, pharmacogenomic models for genetic variations in antifungal pharmacokinetics can be derived. Pharmacogenomic factors may become especially important in the treatment of immunocompromised patients or those with persistent or refractory mycoses that cannot be explained by elevated MICs and where rational dosage optimization of the antifungal agent may be particularly critical. Pharmacogenomics has the potential to shift the paradigm of therapy and to improve the selection of antifungal compounds and adjustment of dosage based upon individual variations in drug absorption, metabolism, and excretion.

Therapies for Onychomycosis: A Review

Onychomycosis, a chronic fungal infection of the nail, can be treated using various modalities. Surgical, chemical, topical, and oral methods are reviewed in this article, with an emphasis on the three systemic treatments approved by the US Food and Drug Administration: terbinafine, itraconazole, and griseofulvin.

Suppressive effects of antimycotics on tumor necrosis factor-alpha-induced CCL27, CCL2, and CCL5 production in human keratinocytes

Antimycotic agents are reported to improve cutaneous symptoms of atopic dermatitis or psoriasis vulgaris. Keratinocytes in these lesions excessively produce chemokines, CCL27, CCL2, or CCL5 which trigger inflammatory infiltrates. Tumor necrosis factor-alpha (TNF-alpha) induces production of these chemokines via activating nuclear factor-kappaB (NF-kappaB). We examined in vitro effects of antimycotics on TNF-alpha-induced CCL27, CCL2, and CCL5 production in human keratinocytes. Antimycotics ketoconazole and terbinafine hydrochloride suppressed TNF-alpha-induced CCL27, CCL2, and CCL5 secretion and mRNA expression in keratinocytes in parallel to the inhibition of NF-kappaB activity while fluconazole was ineffective. Anti-prostaglandin E2 (PGE2) antiserum or antisense oligonucleotides against PGE2 receptor EP2 or EP3 abrogated inhibitory effects of ketoconazole and terbinafine hydrochloride on TNF-alpha-induced NF-kappaB activity and CCL27, CCL2, and CCL5 production, indicating the involvement of endogenous PGE2 in the inhibitory effects. Prostaglandin H2, a precursor of PGE2 can be converted to thromboxane A2. Ketoconazole, terbinafine hydrochloride and thromboxane A2 synthase (EC 5.3.99.5) inhibitor, carboxyheptyl imidazole increased PGE2 release from keratinocytes and reduced that of thromboxane B2, a stable metabolite of thromboxane A2. Carboxyheptyl imidazole also suppressed TNF-alpha-induced NF-kappaB activity and CCL27, CCL2, and CCL5 production. These results suggest that ketoconazole and terbinafine hydrochloride may suppress TNF-alpha-induced NF-kappaB activity and CCL27, CCL2, and CCL5 production by increasing PGE2 release from keratinocytes. These antimycotics may suppress thromboxane A2 synthesis and redirect the conversion of PGH2 toward PGE2. These antimycotics may alleviate inflammatory infiltration in atopic dermatitis or psoriasis vulgaris by suppressing chemokine production.

Treatment of onychomycosis with oral antifungal agents

Onychomycosis is the most common nail disease and describes the invasion of the nail by fungi. Different clinical patterns of infection depend on the way and the extent by which fungi colonise the nail: distal subungual onychomycosis, proximal subungual onychomycosis, white superficial onychomycosis, endonyx onychomycosis and total dystropic onychomycosis. The type of nail invasion depends on both the fungus responsible and on host susceptibility. Treatment of onychomycosis depends on the clinical type of the onychomycosis, the number of affected nails and the severity of nail involvement. The goals for antifungal therapy are mycological cure and a normal looking nail. In this paper the treatment of onychomycosis with oral antifungal agents will be reviewed.

The novel antifungal agent PLD-118 is neither metabolized by liver microsomes nor inhibits cytochrome P450in vitro

PLD-118 is a novel, oral antifungal drug, under development for the treatment of Candida infections. Possible metabolism of PLD-118 by rat, dog and human S9 liver homogenates and inhibition of human cytochrome P450 (CYP) enzymes were investigated. PLD-118 (10 and 100 microM) incubated for 0-60 min with S9 fractions and NADPH was determined by HPLC, using the Waters AccQ.Tag method after derivatization of amino acids to stable, fluorescent derivatives. CYP assays were performed using pooled human liver microsomes with substrates, selective towards human CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A, incubated at concentrations around the Km. Incubation mixtures were preincubated with PLD-118 (0.1-100 microM) or control inhibitor for 5 min. No metabolism of PLD-118 was detected with rat and dog S9 fractions. A small (8%) decrease in PLD-118 at 100 microM (not detected at 10 microM) with human microsomes was considered to be biologically irrelevant. PLD-118 did not inhibit any of the tested CYPs. PLD-118, at concentrations up to 100 microM, is not metabolized by rat, dog or human liver S9 homogenates and does not inhibit human CYPs in vitro, suggesting little likelihood for interaction of PLD-118 with drugs metabolized by these enzymes.

Influence of human nail etching for the assessment of topical onychomycosis therapies

The purpose of this investigation was to study the physico-chemical properties of hot-melt extruded films containing ketoconazole and to determine the influence of 'nail etching' on film bioadhesion and drug permeability for the assessment of topical onychomycosis therapies. Hot-melt extrusion (HME) was used to prepare films containing 20% w/w ketoconazole. Ketoconazole 0.125% gel was also prepared using Carbopol 974P NF. Films were processed at a temperature range of 115-120 degrees C utilizing a Killion extruder (KLB-100), and were evaluated for post-extrusion drug content, content uniformity, bioadhesion, thermal behavior and nail drug permeation. The extruded films demonstrated excellent content uniformity and post-processing drug content. Tensile and peel tests were recorded to determine the bioadhesive profiles. In this study, work of adhesion and peak adhesive force determinations using the peel tests provided more sensitive results for evaluating the bioadhesivity of the HME films than the tensile tests. The in vitro permeability profiles have demonstrated, that nail samples treated with an 'etchant' demonstrated a significant increase in drug permeability compared to control. Differential scanning calorimetry (DSC) thermograms indicated that ketoconazole was in solid solution within the HME films. These findings are encouraging for the future design and formulation of novel drug delivery systems for the topical treatment of onychomycosis.

Treatment of dermatophytosis in dogs and cats: review of published studies

The recent literature on the treatment of dermatophytosis in dogs and cats was reviewed. Based upon in vitro studies using isolated infected hairs and controlled or field in vivo studies, the following topical treatments were consistently found to be antifungal (i.e. antidermatophyte): lime sulfur (1:16), 0.2% enilconazole rinses, and a combined 2% miconazole/chlorhexidine shampoo. Animals or hairs were either bathed or rinsed once or twice weekly. Itraconazole, griseofulvin and terbinafine were evaluated in controlled or field studies, most commonly involving cats. Griseofulvin (50 mg kg(-1)) was reported to cure infected animals in 41-70 days. Itraconazole (10 mg kg(-1) once daily or in a combined daily/pulse therapy 10 mg kg(-1) once daily for 28 days and then week on/week off) was reported to cure infected animals in 56-70 days. Low-dose itraconazole (1.5-3.0 mg kg(-1)) in 15-day cycles required 1-3 cycles (15-45 days). Various doses of terbinafine (5-40 mg kg(-1)) were reportedly used to treat dogs or cats. The higher doses of terbinafine (> 20 mg kg(-1)) were required to achieve a mycological cure; the number of treatment days to cure varied from 21 to > 126 days. Lufenuron was reported anecdotally to be an effective cure, however, this was not substantiated in controlled studies. Finally, fungal vaccines were not found to be effective against challenge exposure, however, there is evidence that they may be useful in treatment protocols.

The use of oral antifungal agents to treat onychomycosis

Onychomycosis has been treated for years with oral antifungal agents, and more recently in the United States with a topical nail lacquer. Griseofulvin was the first significant oral agent available to manage onychomycosis. The introduction of the azoles (ketoconazole, itraconazole, and fluconazole) and the allylamine, terbinafine, led to improved cure rates and a broad spectrum of activity. Pharmacokinetic studies have shown that the newer oral agents penetrate the nail within approximately one to two weeks after the start of therapy and remain for several months after the end of treatment. This article reviews the oral antifungal agents used to treat onychomycosis.