Advances in Topical Drug Delivery Systems for the Management of Tinea Pedis (Athlete’s Foot): A Comprehensive Review

 Ayan Biswas, Bratati Das, Souradip Pal, Sourish Maity, Sanjiban Utpalkumar Sarkar, Nityananda Mondal*

Department of Pharmaceutics, BCDA College of Pharmacy and Technology,

Hridaypur, Barasat, Kolkata 700127, West Bengal, India.

*Correspondence: nmondal1@yahoo.co.in

DOI: https://doi.org/10.71431/IJRPAS.2026.5626

INTRODUCTION

Few skin complaints are as familiar as athlete’s foot. A dermatophyte infection confined to the feet, it appears most often once puberty has passed and spreads readily—either skin-to-skin or by way of the damp surfaces of changing rooms, poolsides, gym floors, shared towels, and the inside of shoes ^1,2. Several converging trends—denser city living, the popularity of indoor sport, the long hours many people spend in closed footwear, and an ageing population—have all nudged its frequency upward ^3,4. The fungi responsible feed on keratin, and one species, Trichophyton rubrum, dominates the picture worldwide; T. interdigitale and E. floccosum account for most of the remainder ^4,5. Armed with keratinases, proteases, and lipases, these organisms anchor themselves to the skin, break it down for nourishment, and set up the scaling, redness, cracking, itching, and sogginess that define the disease ¹⁹. Taken together, the dermatophytoses are thought to trouble roughly a fifth to a quarter of people on the planet—reason enough to treat them as a public-health matter rather than a trivial nuisance ¹⁹.

Who develops the infection depends on a mix of climate, biology, and behaviour: warmth and damp, sweaty feet, neglected hygiene, diabetes, a weakened immune system, excess weight, and shoes that trap moisture all raise the odds, which is why athletes, soldiers, and industrial workers are over-represented ^2,3. The disease shows itself in four recognisable patterns—between the toes, across the sole like a moccasin, as blisters, or as ulcers. Pinning down the diagnosis draws on the clinical picture supported, where needed, by potassium-hydroxide microscopy, culture, histology, and the newer molecular and mass-spectrometry techniques ^20,21,22. The drugs themselves are effective, but the same recurring obstacles—shallow penetration, fleeting contact with the skin, abandoned courses, and creeping resistance—keep undermining them ^8,9,10,11. That gap between potent molecules and disappointing real-world cure rates is exactly what the newer carrier systems set out to close ^{12,13,14,15,16,17,18}. This article therefore walks through the disease in turn—its spread, its biology, how it is recognised and currently treated—before examining what these delivery technologies add and where their limits lie.

AIM OF THE REVIEW

The purpose of this review is to bring together, in one place, the clinical reality of tinea pedis and the pharmaceutical science now being directed at it, so that the connection between the two is made explicit. Specifically, the article sets out to: (i) summarise the current understanding of the epidemiology, causative organisms, and pathogenesis of the infection; (ii) outline how the disease is recognised clinically and confirmed in the laboratory; (iii) appraise the conventional topical and systemic antifungals together with the practical reasons they so often fall short; and (iv) critically examine the range of novel nanocarrier-based delivery systems—vesicular, lipid-based, emulsion, and particulate—that aim to overcome those shortcomings. A further aim is to look honestly at the obstacles standing between promising laboratory results and approved products, and to identify the directions in which the field is most likely to move. By framing the delivery-science advances against the specific failings of standard therapy, the review is intended to be useful both to formulation scientists seeking clinically relevant targets and to clinicians wishing to understand what the next generation of antifungal products may offer.

OVERVIEW OF TINEA PEDIS

At its core, athlete’s foot is a dermatophyte feeding on the keratin of the feet. The infection favours the spaces between the toes, the soles, and the sides of the foot, and in long-standing cases it may creep onto the nails or neighbouring skin ^1,4. The popular name harks back to its prevalence among sportspeople—a consequence of sweat, enclosed shoes, and shared changing rooms—though in truth it spares no age group or occupation. Once a fungus has fastened onto the outer skin, it releases keratin-splitting enzymes, takes up residence in the surface layers, and provokes the redness, flaking, itching, and occasional blistering or ulceration that bring patients to the clinic ¹⁹. What makes the disease so stubborn is its habit of coming back: courses left unfinished, spores lingering in shoes and nails, reinfection from the environment, and lax foot care all conspire to keep it alive, and the breached skin can let bacteria in—a particular danger for those with diabetes or compromised immunity ^1,2.

Classification of Tinea Pedis

Clinicians distinguish four presentations, and a single patient may show more than one at once (Table 1). The interdigital type, by far the commonest, settles in the cleft between the fourth and fifth toes with flaking, sogginess, cracking, and itch. The moccasin type spreads dry, thickened scale across the sole and heel in the distribution its name suggests and tends to become chronic, usually at the hands of T. rubrum. The vesiculobullous type erupts acutely as inflamed blisters over the arch or instep, while the ulcerative type—the gravest—breaks down into rapidly enlarging erosions with bacterial superinfection and is seen mainly in diabetic or immunosuppressed patients.

Table 1. Clinical classification of tinea pedis by lesion morphology and anatomical distribution^1,4

EPIDEMIOLOGY

By most reckonings, no superficial mycosis is encountered more often, and its mix of wide reach, stubborn relapse, and easy spread places a real cost on both patients and health services ^1,3. Surveys put the worldwide prevalence at around three per cent at any given time, while the chance of being affected at some point in life may climb as high as seventy per cent; the condition is decidedly an adult one, scarce before puberty and most concentrated between about sixteen and forty-five years ^1,23. Heat, humidity, and shoes that seal in moisture all help the fungus along, and reported rates tend to run higher in industrialised countries and in men ^3,24. Among children the numbers vary enormously—one pooled analysis recorded anywhere from 0.03% to 15.6%, again with dermatophytes, T. rubrum foremost, doing most of the damage ²⁵. A decades-long laboratory record is telling: T. rubrum and T. interdigitale between them yielded roughly 99% of foot and nail isolates, whereas E. floccosum, once common, has all but faded from many regions ⁵.

Diabetes mellitus, immunosuppression, obesity, hyperhidrosis, peripheral vascular disease, and advanced age increase susceptibility ^1,2. Recurrence remains substantial owing to incomplete eradication, poor adherence, contaminated footwear, and untreated onychomycosis, sustaining tinea pedis as a reservoir for dermatophytosis elsewhere ^1,52,53. The epidemiological landscape has also shifted in recent years: in the Indian subcontinent and increasingly worldwide, the terbinafine-resistant species Trichophyton indotineae (formerly classified within the T. mentagrophytes/T. interdigitale complex) has driven an epidemic of chronic, widespread, recalcitrant dermatophytosis, underscoring how species distribution and resistance patterns evolve over time and across regions ^11,53,55. Reported prevalence figures across the major at-risk groups are summarised in Table 2.

Table 2. Prevalence and distribution of tinea pedis across populations^1,3,23

ETIOLOGY AND CAUSATIVE ORGANISMS

Tinea pedis is caused mainly by dermatophytes—keratinophilic fungi of the genera Trichophyton, Microsporum, and Epidermophyton that secrete keratinolytic enzymes to colonise the stratum corneum ^4,19. Dermatophytes are ecologically classified as anthropophilic, zoophilic, or geophilic; most tinea pedis is caused by anthropophilic species adapted to humans, enabling prolonged colonisation and recurrence ^4,5. T. rubrum is the leading agent, causing chronic interdigital and moccasin disease and frequently associated with onychomycosis, partly by evading host inflammation ^4,19. T. interdigitale tends to cause more acute, inflammatory, vesiculobullous lesions and is readily transmitted in communal settings ⁴. E. floccosum colonises skin and nails (but not hair) and has declined in many countries ⁵. Non-dermatophyte moulds (e.g., Neoscytalidium, Scopulariopsis, Fusarium) and Candida occasionally contribute, especially in immunocompromised hosts ¹. Pathogenicity depends on adhesins, keratinases, proteases (subtilisins and metalloproteases), lipases, immune-evasion mechanisms, and biofilm formation ¹⁹. The initial degradation of native keratin begins with sulfitolysis, which reduces the disulphide bonds that stabilise keratin, after which secreted endoproteases (subtilisin-like Sub proteins and fungalysin metalloproteases, Mep) and exoproteases (leucine aminopeptidases and dipeptidyl peptidases) hydrolyse the protein into assimilable peptides and amino acids ¹⁹. Different species and clinical contexts express distinct enzyme repertoires; for example, Sub3, Sub4, and Mep4 are implicated in invasion of skin by T. rubrum, and expression of several proteases is upregulated in the presence of keratin substrates, illustrating the close adaptation of these fungi to keratinised tissue ¹⁹. The principal organisms responsible, their ecological type, and their typical clinical behaviour are compared in Table 3.

Table 3. Principal causative organisms of tinea pedis^1,4,5,11

PATHOGENESIS

Pathogenesis reflects the interaction between dermatophyte virulence and host skin defences and proceeds through exposure, adhesion, keratin degradation, immune interaction, and (in chronic disease) immune evasion and biofilm formation ¹⁹. Infectious propagules (arthroconidia, hyphal fragments) from contaminated environments adhere to the stratum corneum via surface adhesins; warm, moist, occluded conditions favour adhesion and growth ¹⁹. Colonising fungi secrete keratinases together with subtilisin-like serine proteases (e.g., Sub3, Sub4) and metalloproteases (e.g., Mep4), which degrade keratin and mediate invasion, generally without penetrating viable tissue ¹⁹.

Keratinocytes recognise fungal cell-wall components through pattern-recognition receptors, including Toll-like and C-type lectin receptors, triggering IL-1, IL-6, IL-17, TNF-α, and IFN-γ and recruiting neutrophils and macrophages ¹⁹. Cell-mediated immunity is the principal protective mechanism; impaired cellular immunity predisposes to severe, extensive, recurrent disease. Chronic T. rubrum infection is associated with blunted inflammation through immunomodulatory metabolites and antigenic modification, promoting persistence ¹⁹. Biofilms—fungal communities within a self-produced matrix—limit drug penetration and reduce antifungal susceptibility, contributing to chronic and recurrent infection and motivating advanced delivery systems ^9,19. The full sequence—from initial exposure through adhesion, invasion, and the host
response to eventual chronicity—is depicted in Figure 1.

Figure 1. Sequential stages of dermatophyte infection in tinea pedis and their clinical determinants

RISK FACTORS

Tinea pedis is multifactorial. Environmental factors—heat, humidity, and communal facilities (pools, locker rooms, showers)—promote survival and transmission ^3,24. Host factors include age (rare before puberty), male predominance, and possible genetic variation in immunity and barrier function ^1,3. Lifestyle factors include occlusive or synthetic footwear, poor foot hygiene, sharing of footwear/towels, athletic activity, and hyperhidrosis ^1,2. Comorbidities—diabetes mellitus, obesity, immunosuppression (HIV, malignancy, transplantation, corticosteroids), and peripheral vascular disease—increase severity and chronicity ². Recurrence is driven by inadequate treatment duration, poor adherence, contaminated footwear, untreated onychomycosis, and biofilm-associated resistance ^1,9. Prevention centres on foot hygiene, dryness, breathable footwear, protective footwear in communal areas, hyperhidrosis control, and treatment of concomitant onychomycosis ¹. These contributory factors are grouped by category in Table 4.

Table 4. Major risk factors for tinea pedis^1,2,3

CLINICAL MANIFESTATIONS

Presentation varies with organism, host immunity, chronicity, and environment, ranging from mild scaling and pruritus to extensive ulceration ^1,2. Typical features include pruritus, burning, scaling, erythema, maceration, fissuring, vesiculation, and malodour. The interdigital form (most common) affects the fourth/fifth web spaces with itching, maceration, white soggy skin, and fissures, often with secondary bacterial colonisation. Moccasin-type disease shows chronic, diffuse hyperkeratotic scaling of the soles/heels, commonly due to T. rubrum and harder to treat. The vesiculobullous form is acute and inflammatory, frequently reflecting hypersensitivity, while the ulcerative form is severe, with rapidly progressing erosions and secondary infection, mainly in immunocompromised or diabetic patients ^1,2. Complications include secondary bacterial infection (e.g., Staphylococcus aureus, Streptococcus pyogenes) with cellulitis, spread to nails (onychomycosis) acting as a reservoir, recurrent dermatophytosis, and reduced quality of life ¹. Differential diagnoses include dyshidrotic/atopic eczema, palmoplantar psoriasis, contact dermatitis, interdigital candidiasis, and erythrasma/bacterial infection, so laboratory confirmation is advisable before prolonged therapy ^2,20.

Clinical severity is influenced strongly by the causative organism and the host. Anthropophilic species such as T. rubrum tend to produce indolent, minimally inflammatory, chronic disease that patients may tolerate for months or years, whereas more inflammatory organisms and hypersensitivity reactions (the so-called dermatophytid or “id” reaction) can produce vesicular eruptions at sites distant from the primary infection ^2,19. In diabetic and immunocompromised individuals, fissuring and maceration provide a portal of entry for bacteria, and lower-limb cellulitis is frequently preceded by interdigital tinea pedis; effective treatment of the fungal infection therefore reduces the risk of recurrent bacterial complications ². Beyond physical morbidity, persistent pruritus, malodour, and visible scaling carry a measurable impact on quality of life, social interaction, and footwear choice, and recurrent disease imposes repeated treatment costs and time away from sport or work ^1,3.

DIAGNOSIS

Because several dermatoses mimic tinea pedis, diagnosis combines clinical assessment with laboratory confirmation, particularly in chronic, atypical, or refractory cases ^2,20. KOH microscopy of lesion-margin scrapings in 10–20% potassium hydroxide is rapid and inexpensive, revealing branching septate hyphae and arthroconidia, but does not identify species and may yield false negatives ²⁰. Fungal culture on Sabouraud dextrose agar remains the reference standard for species identification but requires weeks ²⁰. Histopathology with PAS or Gomori methenamine-silver stains aids atypical or refractory cases ²⁰. PCR-based assays provide rapid, sensitive, species-level detection directly from specimens and outperform culture in several settings ²¹, while MALDI-TOF mass spectrometry enables rapid, accurate identification of cultured isolates, with accuracy strongly dependent on extraction protocol and an adequate reference library ^22,26. Future directions include point-of-care molecular testing, rapid dermatophyte platforms, AI-assisted diagnosis, and resistance monitoring ^21,22.

In routine practice the choice of test is dictated by the clinical scenario. For a typical interdigital presentation, empirical topical therapy without laboratory confirmation is often reasonable; confirmation becomes important for chronic, extensive, recurrent, or treatment-resistant disease, before committing a patient to prolonged systemic therapy, and whenever the diagnosis is uncertain because of overlap with eczema or psoriasis ^2,20. A key limitation of KOH microscopy and culture is their dependence on adequate sampling; scrapings should be taken from the active, advancing margin of the lesion after cleansing with alcohol, and prior antifungal use can suppress recovery of the organism ²⁰. Molecular assays and MALDI-TOF mass spectrometry are increasingly valuable not only for speed but for distinguishing closely related species—such as members of the T. mentagrophytes/T. interdigitale complex—that differ in resistance behaviour, information that is becoming clinically actionable as resistance spreads ^21,22,55. The speed, species-level discrimination, and main drawback of each approach are set side by side in Table 5.

Table 5. Comparison of diagnostic methods for tinea pedis^20,21,22,26

CONVENTIONAL TREATMENT APPROACHES

Treatment aims to eradicate the pathogen, relieve symptoms, prevent recurrence, and limit transmission, guided by clinical subtype, severity, nail involvement, adherence, and comorbidities ^1,6. Topical therapy (creams, gels, sprays, solutions, powders) is first-line for mild-to-moderate, localised disease, delivering high local concentrations with minimal systemic exposure; courses typically run one to six weeks ^6,7. Systemic therapy (terbinafine, itraconazole, fluconazole, griseofulvin) is reserved for extensive, moccasin-type, recurrent, hyperkeratotic, refractory, or onychomycosis-associated disease and achieves deeper tissue concentrations, though hepatotoxicity and drug interactions require monitoring ^6,7,51,57. Combination therapy may accelerate clearance and reduce recurrence, especially with coexisting onychomycosis ⁶. Adjunctive measures—foot hygiene, drying, breathable/rotated footwear, moisture and hyperhidrosis control, and decontamination of footwear and surfaces—are essential to prevent relapse ¹. Limitations include poor penetration of the thick plantar stratum corneum, long regimens, premature discontinuation, recurrence/reinfection, and emerging resistance ^8,9,10,11.

Patient adherence is a decisive but often neglected determinant of outcome. Because symptoms typically improve well before the fungus is eradicated, many patients stop applying topical agents early, leaving viable organisms that drive relapse ^7,17. Simplified, once-daily regimens, fixed-duration courses, and clear counselling on continuing therapy beyond symptom resolution measurably improve cure rates. Concurrent management of predisposing factors—tight glycaemic control in diabetes, treatment of hyperhidrosis, weight management in obesity, and correction of footwear habits—addresses the microenvironment that sustains infection ^1,2. Environmental decontamination is equally important: dermatophyte arthroconidia can persist in socks, shoes, and communal flooring for extended periods, and untreated onychomycosis acts as a continual reservoir for cutaneous reinfection. Antifungal foot powders, regular replacement or disinfection of footwear, and avoidance of barefoot walking in communal wet areas are practical, evidence-supported measures ^1,52. Where onychomycosis coexists, systemic therapy or combined topical–systemic regimens are generally required because topical agents alone rarely penetrate the nail plate adequately ^6,32.

ANTIFUNGAL DRUGS USED IN TINEA PEDIS

Most antifungals disrupt the fungal membrane by interfering with ergosterol biosynthesis. Allylamines (terbinafine, naftifine) and the benzylamine butenafine inhibit squalene epoxidase, are fungicidal, allow short regimens, and offer high cure rates; oral terbinafine may cause gastrointestinal upset, taste disturbance, and hepatotoxicity ^6,7,56. Azoles (clotrimazole, miconazole, ketoconazole, econazole, fluconazole, itraconazole) block lanosterol 14α-demethylase; topical agents are broadly active and well tolerated, whereas triazoles offer favourable oral pharmacokinetics but azole drug interactions via cytochrome P450 ^6,7,51. Miconazole additionally has antibacterial activity useful in mixed infection. Ciclopirox chelates polyvalent cations through a multi-target mechanism with low resistance potential; tolnaftate and amorolfine are additional options ^6,7. A major concern is terbinafine resistance, attributed to point mutations in the squalene epoxidase (SQLE) gene—notably Phe397Leu and Leu393Phe—reported with high frequency in Trichophyton interdigitale and in the emergent species T. indotineae, which is largely terbinafine-resistant and best treated with itraconazole ^8,10. The points at which each drug class interrupts ergosterol biosynthesis, and the key resistance mutations, are mapped in Figure 2, while their representative agents, targets, and mode of action are summarised in Table 6.

Figure 2. Antifungal drug classes and their molecular targets within the ergosterol biosynthetic pathway, with key SQLE resistance mutations

Table 6. Antifungal drug classes used in tinea pedis, summarising their representative agents, molecular targets, and mode of action^6,7

LIMITATIONS OF CONVENTIONAL THERAPY

Several factors limit conventional therapy. The densely packed corneocyte–lipid matrix of the stratum corneum restricts drug penetration, especially in hyperkeratotic moccasin disease, leaving sub-therapeutic concentrations at colonised depths ^12,13,42,43. Poor retention—loss by sweating, friction, washing, and skin turnover—shortens exposure and necessitates frequent reapplication ^14,18. Long regimens promote premature discontinuation once symptoms improve, leaving viable organisms and driving relapse; greasy or inconvenient formulations further reduce adherence ^13,14. Oral therapy carries hepatotoxicity, cytochrome P450-mediated interactions, and gastrointestinal effects ^6,7. Recurrence is sustained by incomplete eradication, contaminated footwear, untreated onychomycosis, environmental reservoirs, and biofilm-mediated reduced susceptibility ^1,9. Finally, emerging terbinafine resistance via SQLE mutations threatens current regimens ^8,10,11. An ideal topical system would enhance penetration and retention, provide sustained release, reduce dosing frequency, limit systemic exposure, and help overcome biofilm and resistance—objectives addressed by nanocarriers ^{12,13,14,15,16,17,18}.

Several of these limitations are interrelated and compound one another. Poor penetration and short residence time both lower the effective drug concentration at the colonised depth, which in turn favours survival of a fungal subpopulation; that surviving population is precisely what sustains biofilm-associated tolerance and provides the genetic reservoir from which resistant mutants can be selected, especially under the sub-inhibitory exposure produced by incomplete courses ^9,13,54. An effective formulation must therefore do more than carry an active drug: it should improve the pharmacokinetic profile within the skin so that the drug remains above its minimum inhibitory concentration throughout the treatment interval while remaining cosmetically acceptable enough to support adherence ^12,15,17. These requirements—deeper and more uniform delivery, prolonged local retention, controlled release, low irritancy, physical stability, and feasible manufacturing—define the design targets for the nanocarrier systems discussed in the next section ^12,15,16,47.

NOVEL TOPICAL DRUG DELIVERY SYSTEMS

Nanotechnology-based carriers improve solubility, controlled release, permeation, retention, and patient acceptability while reducing systemic exposure ^{12,15,16,47,49,50}. They are broadly grouped into vesicular, lipid-based, emulsion, and particulate systems, as set out in Figure 3.

Figure 3. Classification of novel topical drug delivery systems for tinea pedis and their shared therapeutic goals

Vesicular Systems

Liposomes are phospholipid-bilayer vesicles encapsulating hydrophilic and lipophilic drugs; liposomal terbinafine, clotrimazole, and ketoconazole show improved skin deposition and antifungal activity, although physical instability, leakage, and cost remain challenges ^16,17,39. Niosomes (non-ionic surfactant vesicles) offer greater stability and lower cost; niosomal clotrimazole, ketoconazole, and luliconazole gels enhance retention and activity versus conventional creams ^28,29. Transferosomes are ultra-deformable vesicles that squeeze through intercellular spaces, improving deep deposition—attractive for hyperkeratotic disease ^16,37,38. Ethosomes, containing high ethanol concentrations, fluidise stratum-corneum lipids and markedly enhance permeation of agents such as terbinafine and fluconazole ^35,36.

Emulsion Systems

Nanoemulsions (droplets ~20–200 nm) provide a large surface area that improves solubility and permeation of clotrimazole, miconazole, ketoconazole, terbinafine, and luliconazole ^30,34. Nanoemulgels combine a nanoemulsion carrier with a hydrogel matrix to improve viscosity, spreadability, and residence time; ketoconazole and butenafine nanoemulgels have shown faster cure and larger inhibition zones than conventional vehicles, and ketoconazole nanoemulgel improved trans-ungual permeation and activity against Trichophyton rubrum ^31,32,33.

Lipid-based and Particulate Systems

Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) provide occlusion, controlled release, and enhanced penetration; terbinafine SLNs increased drug levels across stratum corneum, epidermis, and dermis ^14,40,41, while terbinafine NLCs (~128–132 nm) gave sustained release and, in a randomised double-blind clinical trial as a 1% gel, demonstrated favourable antifungal performance ^12,18. Deformable-membrane vesicles loaded with griseofulvin have also shown enhanced efficacy in a guinea-pig tinea pedis model ⁵⁸. Polymeric nanoparticles of PLGA, chitosan, polycaprolactone, or alginate enable sustained release, stability, and targeting; terbinafine-loaded PLGA nanoparticles have been developed specifically for tinea ^13,15,48. Nanocarriers enhance delivery through lipid fusion/fluidisation, follicular targeting, deformability, ethanol-mediated permeation, controlled release, improved solubility, and potential biofilm penetration ^12,15,16; these routes across the skin layers are illustrated in Figure 4, and the principal carrier types with their representative drug applications are collated in Table 7.

Figure 4. Mechanisms of enhanced skin delivery by nanocarriers across the skin layers

Table 7. Novel topical delivery systems and representative antifungal applications ^{16,17,18,28,29,32,33,34,58}

RECENT ADVANCES AND CURRENT RESEARCH

Research increasingly integrates nanotechnology, biomaterials, and advanced formulation to improve delivery efficiency, penetration, biofilm targeting, and treatment duration ^12,15,16. Terbinafine- and clotrimazole-loaded nanoformulations attract particular attention for their broad activity and safety ^12,30. Biofilm-targeted strategies—surface-active formulations, enhanced nanoparticle penetration, enzyme-mediated matrix degradation, and combination therapy—aim to overcome biofilm-associated resistance ^9,15. Combination delivery (antifungal with anti-inflammatory, penetration enhancer, or antimicrobial; multi-drug nanocarriers) may provide synergy ¹⁵. Microneedle-assisted delivery creates micro-conduits across the stratum corneum, promising for hyperkeratotic and refractory disease, while stimuli-responsive (“smart”) systems release drug in response to pH, temperature, enzymes, or fungal metabolites ^{15,16,44,45,46}. Phytopharmaceuticals (tea tree oil, neem, curcumin, aloe vera, essential oils) are being nanoencapsulated to improve stability and bioavailability ^30,33,59, and artificial-intelligence and computational methods are emerging for formulation optimisation, predictive modelling, and personalised therapy ^15,60. Large-scale clinical trials remain necessary before broad implementation ¹⁸.

Despite a large and rapidly growing body of preclinical work, a clear translational gap persists between laboratory performance and approved products. The great majority of published nanocarrier studies for tinea pedis report in vitro release, ex vivo permeation across animal skin, and small in vivo efficacy experiments, whereas randomised controlled trials in patients remain scarce ^12,18,60. Bridging this gap requires standardised characterisation (particle size, polydispersity, zeta potential, entrapment efficiency, and physical stability on storage), validated and scalable manufacturing, and head-to-head comparison against marketed conventional formulations using mycological cure—not merely symptom relief—as the primary endpoint ^15,16,47. Encouragingly, a double-blind randomised clinical trial of a terbinafine nanostructured-lipid-carrier gel has demonstrated that such systems can be evaluated rigorously in humans and can match or exceed conventional creams, providing a template for the field ¹⁸.

CHALLENGES AND FUTURE PERSPECTIVES

Despite progress, scientific, clinical, regulatory, and economic barriers persist. Antifungal resistance—especially terbinafine resistance via SQLE mutations and the spread of T. indotineae—threatens current regimens and underscores the need for surveillance and alternatives ^8,10,11,27. High recurrence, biofilm formation, and poor adherence remain clinical challenges ^1,9. For nanocarriers, manufacturing complexity, scale-up and reproducibility, physical/chemical stability, limited regulatory frameworks, and cost constrain translation, particularly in low- and middle-income settings where disease burden is high ^12,15,16. Future directions include smart and targeted delivery, personalised medicine informed by genomics and molecular diagnostics, microneedle platforms, rational combination formulations, multifunctional and hybrid (lipid–polymer) nanocarriers, green nanotechnology, and AI-assisted development ^15,16. Successful translation requires collaboration among pharmaceutical scientists, dermatologists, microbiologists, engineers, and regulators, prioritising large-scale trials, long-term safety, cost-effectiveness, and commercialisation ^16,18.

A further priority is antifungal stewardship. The current resistance crisis has been fuelled in part by inappropriate practices—over-the-counter sales of potent topical corticosteroid–antifungal–antibacterial combination creams, inadequate dosing, and incomplete courses—which select for resistant strains and modify the clinical picture ^52,53,54. Rational prescribing guided by species identification and, where available, antifungal susceptibility testing is increasingly advocated, alongside expert consensus guidance on the management of recalcitrant disease ^54,56. Advanced delivery systems may complement these efforts by maintaining drug concentrations above the minimum inhibitory concentration for longer, potentially reducing the selective pressure that drives resistance; however, this hypothesis requires direct clinical confirmation ^15,60. Finally, equitable access is essential: because the global burden of superficial mycoses falls disproportionately on low- and middle-income regions, affordable, stable, and easily manufactured formulations—rather than only premium nanomedicines—will be needed to translate scientific advances into meaningful public-health benefit ^3,47,50. The principal challenges across the microbial, formulation, clinical, and regulatory domains, together with the solutions now emerging, are brought together in Table 8.

Table 8. Challenges and emerging solutions in tinea pedis management ^{1,8,9,10,14,15,16}

CONCLUSION

Athlete’s foot is unlikely to disappear from the clinic any time soon. Driven mostly by T. rubrum and T. interdigitale, it keeps generating consultations through its itch, its persistence, and the toll it takes on everyday comfort ^1,2,3,4,5. Getting the diagnosis right—clinically, and with laboratory backup when the picture is murky—remains the foundation on which sensible treatment is built. The familiar topical and oral antifungals still anchor that treatment, yet they keep running into the same walls: too little drug reaching the fungus, too little staying put, courses cut short, biofilms shrugging off therapy, and resistance gaining ground ^{6,7,8,9,10,11}. This is where the nanometre-scale carriers earn their interest. By dissolving stubborn drugs, ferrying them deeper, anchoring them in the skin, and letting them out slowly, vesicles, emulsion gels, and lipid or polymer particles promise better results with less collateral exposure ^{12,13,14,15,16,17,18}. Pair them with biofilm-busting strategies, microneedles, stimulus-triggered release, computational design, and treatment tailored to the individual, and a genuinely more effective, more bearable era of antifungal care comes into view. What stands between promise and practice is unglamorous but essential—rigorous trials, honest safety data, clear regulatory pathways, and manufacturing that ordinary health systems can afford ^15,16,18.

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