Results from Phase 1/2 trial of BB2603, a terbinafine‐based topical nano‐formulation, in onychomycosis and tinea pedis

Nanoformulations for dismantling fungal biofilms: The latest arsenals of antifungal therapy

Globally, fungal infections have evolved as a strenuous challenge for clinicians, particularly in patients with compromised immunity in intensive care units. Fungal co-infection in Covid-19 patients has made the situation more formidable for healthcare practitioners. Surface adhered fungal population known as biofilm often develop at the diseased site to elicit antifungal tolerance and recalcitrant traits. Thus, an innovative strategy is required to impede/eradicate developed biofilm and avoid the formation of new colonies. The development of nanocomposite-based antibiofilm solutions is the most appropriate way to withstand and dismantle biofilm structures. Nanocomposites can be utilized as a drug delivery medium and for fabrication of anti-biofilm surfaces capable to resist fungal colonization. In this context, the present review comprehensively described different forms of nanocomposites and mode of their action against fungal biofilms. Amongst various nanocomposites, efficacy of metal/organic nanoparticles and nanofibers are particularly emphasized to highlight their role in the pursuit of antibiofilm strategies. Further, the inevitable concern of nanotoxicology has also been introduced and discussed with the exigent need of addressing it while developing nano-based therapies. Further, a list of FDA-approved nano-based antifungal formulations for therapeutic usage available to date has been described. Collectively, the review highlights the potential, scope, and future of nanocomposite-based antibiofilm therapeutics to address the fungal biofilm management issue.

Contemporary Techniques and Potential Transungual Drug Delivery Nanosystems for The Treatment of Onychomycosis

The humanoid nail is considered an exceptional protective barrier that is formed mainly from keratin. Onychomycosis is the cause of 50% of nail infections that is generally caused by dermatophytes. Firstly, the infection was regarded as a cosmetic problem but because of the tenacious nature of onychomycosis and its relapses, these infections have attracted medical attention. The first line of therapy was the oral antifungal agents which were proven to be effective; nevertheless, they exhibited hepato-toxic side effects, alongside drug interactions. Following, the opportunity was shifted to the topical remedies, as onychomycosis is rather superficial, yet this route is hindered by the keratinized layers in the nail plate. A potential alternative to overcome the obstacle was applying different mechanical, physical, and chemical methods to boost the penetration of drugs through the nail plate. Unfortunately, these methods might be expensive, require an expert to be completed, or even be followed by pain or more serious side effects. Furthermore, topical formulations such as nail lacquers and patches do not provide enough sustaining effects. Recently, newer therapies such as nanovesicles, nanoparticles, and nanoemulsions have emerged for the treatment of onychomycosis that provided effective treatment with possibly no side effects. This review states the treatment strategies such as mechanical, physical, and chemical methods, and highlights various innovative dosage forms and nanosystems developed in the last 10 years with a focus on advanced findings regarding formulation systems. Furthermore, it demonstrates the natural bioactives and their formulation as nanosystems, and the most relevant clinical outcomes.

Tinea pedis: an updated review

Background

Tinea pedis is one of the most common superficial fungal infections of the skin, with various clinical manifestations. This review aims to familiarize physicians with the clinical features, diagnosis and management of tinea pedis.

Methods

A search was conducted in April 2023 in PubMed Clinical Queries using the key terms 'tinea pedis' OR 'athlete's foot'. The search strategy included all clinical trials, observational studies and reviews published in English within the past 10 years.

Results

Tinea pedis is most often caused by Trichophyton rubrum and Trichophyton interdigitale. It is estimated that approximately 3% of the world population have tinea pedis. The prevalence is higher in adolescents and adults than in children. The peak age incidence is between 16 and 45 years of age. Tinea pedis is more common amongst males than females. Transmission amongst family members is the most common route, and transmission can also occur through indirect contact with contaminated belongings of the affected patient. Three main clinical forms of tinea pedis are recognized: interdigital, hyperkeratotic (moccasin-type) and vesiculobullous (inflammatory). The accuracy of clinical diagnosis of tinea pedis is low. A KOH wet-mount examination of skin scrapings of the active border of the lesion is recommended as a point-of-care testing. The diagnosis can be confirmed, if necessary, by fungal culture or culture-independent molecular tools of skin scrapings. Superficial or localized tinea pedis usually responds to topical antifungal therapy. Oral antifungal therapy should be reserved for severe disease, failed topical antifungal therapy, concomitant presence of onychomycosis or in immunocompromised patients.

Conclusion

Topical antifungal therapy (once to twice daily for 1-6 weeks) is the mainstay of treatment for superficial or localized tinea pedis. Examples of topical antifungal agents include allylamines (e.g. terbinafine), azoles (e.g. ketoconazole), benzylamine, ciclopirox, tolnaftate and amorolfine. Oral antifungal agents used for the treatment of tinea pedis include terbinafine, itraconazole and fluconazole. Combined therapy with topical and oral antifungals may increase the cure rate. The prognosis is good with appropriate antifungal treatment. Untreated, the lesions may persist and progress.

Novel and Investigational Treatments for Onychomycosis

Onychomycosis is a common nail disease caused by fungi. The primary pathogens are dermatophytes; however, yeasts, non-dermatophyte moulds, and mixed fungal populations may also contribute to the development of a recalcitrant condition, usually accompanied by difficulties in everyday life and severe emotional stress. Treatment failure and relapse of the infection are the most frequent problems, though new issues have become the new challenges in the therapeutic approach to onychomycosis. Resistance to antifungals, an increasing number of comorbidities, and polydrug use among the ageing population are imperatives that impose a shift to safer drugs. Topical antifungals are considered less toxic and minimally interact with other drugs. The development of new topical drugs for onychomycosis is driven by the unmet need for effective agents with prolonged post-treatment disease-free time and a lack of systemic impact on the patients’ health. Efinaconazole, Tavaborole, and Luliconazole have been added to physicians’ weaponry during the last decade, though launched on the market of a limited number of countries. The pipeline is either developing new products (e.g., ME-1111 and NP213) with an appealing combination of pharmacokinetic, efficacy, and safety properties or reformulating old, well-known drugs (Terbinafine and Amphotericin B) by using new excipients as penetration enhancers.