Home | Featured Articles | Continuing Education | Subscribe
SEARCH Advanced Search
The Role of the Pharmacist in Managing Patients with Tinea Pedis: Enhancing Treatment Adherence Improves Patient Outcomes

 
 

Release Date:  April 1, 2007 

Expiration Date: April 30, 2009 

Supported by an educational grant from Novartis Consumer Health.

FACULTY:
W. Steven Pray, PhD, DPh
Bernhardt Professor of Nonprescription Products and Devices
College of Pharmacy
Southwestern Oklahoma State University
Weatherford, OK

FACULTY DISCLOSURE STATEMENTS:
Dr. Pray has no actual or potential conflict of interest in relation to this program.

U.S. Pharmacist does not view the existence of relationships as an implication of bias or that the value of the material is decreased. The content of the activity was planned to be balanced, objective, and scientifically rigorous. Occasionally, authors may express opinions that represent their own viewpoint. Conclusions drawn by participants should be derived from objective analysis of scientific data.

 

ACCREDITATION STATEMENTS:
Pharmacists
acpe Postgraduate Healthcare Education, LLC is accredited by the Accreditation Council for Pharmacy Education as a provider of continuing pharmacy education.
Program No.: 430-000-07-006-H01
Credits: 2.0 hours (.20 ceu)

Exam processing inquiries and booklet orders to:
CE Customer Service Manager (800) 825-4696

Direct educational content inquiries to:
CE Director (800) 331-9396

 

TARGET AUDIENCE:
This accredited program is targeted to pharmacists and pharmacy technicians.

 
DISCLAIMER:
Participants have an implied responsibility to use the newly acquired information to enhance patient outcomes and their own professional development. The information presented in this activity is not meant to serve as a guideline for patient management. Any procedures, medications, or other courses of diagnosis or treatment discussed or suggested in this activity should not be used by clinicians without evaluation of their patients' conditions and possible contraindications or dangers in use, review of any applicable manufacturer's product information, and comparison with recommendations of other authorities. 
 
GOAL:
To enable pharmacists to provide the most current information and counseling to patients with tinea pedis. They will be able to discuss various treatment options, stressing the critical nature of adherence to a given treatment regimen in allowing a cure of the condition.
 

OBJECTIVES:  
After completing this article, the pharmacist will be able to:

  1. Review the incidence, prevalence, etiology, transmission, and epidemiology of tinea pedis.
  2. Describe the manifestations of tinea pedis, including methods of formal physician diagnosis and pharmacist recognition of self-treatable cases.
  3. List and describe conditions that mimic tinea pedis.
  4. Describe the sequelae of poorly treated tinea pedis.
  5. Identify methods that may be used to prevent tinea pedis.
  6. Discuss various nonprescription tretaments for tinea pedis, being able to compare each in terms of the probable treatment duration and the impact of number of required daily treatments on patient adherence.




Dermatophytic infections are ubiquitous diseases that cause considerable morbidity for patients. They seldom cause serious problems, but their presence often disfigures the skin, producing intense pruritus and considerable pain. While nonprescription products seldom cure minor conditions, they can effectively eliminate the pathogens responsible for several dermatophytic conditions, such as tinea pedis. However, effecting a cure with nonprescription antifungal medications is critically dependent on patient adherence to the FDA-approved dosing regimens. For this reason, pharmacists must be fully knowledgeable of the various nonprescription tinea pedis treatment options and their comparative abilities to produce a rapid cure with a minimal number of applications.

Dermatophytic Infections
The epidermis is composed of five distinct layers. The topmost layer is known as the horny layer (stratum corneum) and contains highly keratinized, dead cells. They are continually shed into the environment and replaced by newer cells ascending slowly from the lower layers. Dermatophytic infections affect these keratinized cells, as well as nails and hair, and seldom invade deeper, living tissues.1

Humans are subject to numerous superficial dermatophytic infections, each traditionally named for the site of the body affected.2 Some are considered self-treatable, such as tinea pedis (athlete’s foot), tinea corporis (body ringworm), and tinea cruris (jock itch). However, the U.S. Food and Drug Administration (FDA) has determined that existing nonprescription antifungal agents cannot treat others, such as tinea unguium (onychomycosis), tinea manuum (tinea of the hand), tinea capitis (scalp ringworm), tinea barbae (tinea of the beard and moustache), tinea versicolor, and tinea nigra.

Incidence/Prevalence
Tinea infections are widely acknowledged to be one of the major public health problems throughout the world.1,3 The prevalence of tinea pedis varies somewhat depending on such factors as the age of the population studied and its geographic location, but it is increasing throughout the world.3 In a study of Mexican children aged 2 to 12 years, 21% were found to be symptomatic and to harbor pathogenic dermatophytes, and an additional 7% were asymptomatic but also carried the organisms.3 Tinea pedis may affect 15% to 40% of the U.S. population at any one time; at least 70% of the world’s population will develop it at some time.4-6

Tinea pedis is the most common of all dermatophyte-induced infections.2 Investigators carried out a study of patients attending a dermatology department of a university-affiliated hospital in Monterrey, Mexico.7 All of the 2397 patients had clinical findings indicating the presence of a superficial dermatophyte. Patients were subjected to the standard diagnostic procedures to confirm presence of a cutaneous mycosis. A total of 30.2% of the patients were diagnosed with tinea pedis. Not surprisingly, 25.6% of patients were diagnosed with tinea unguium, an infection closely allied with tinea pedis. The less common tineas diagnosed were tinea capitis (18.4% of patients), tinea corporis (16.4%), and tinea cruris (9.3%).

Etiology/Transmission of Tinea Pedis
It is worth noting that many of the dermatophytes responsible for tineas grow optimally in skin that is moist and warm.2 This propensity explains their preference for intertriginous skin. Intertriginous skin is defined as an area of the skin that is constantly or often in contact with other skin. Thus, the moist, warm recesses of the groin and foot are natural targets.

The causative agents of tinea pedis are the keratinophilic cutaneous mycoses. They are classified into three categories (geophilic, zoophilic, and anthropophilic), depending upon their origin and preferred growth location.2 Geophilic species are thought to have been the prototypical organisms from which the others evolved, living in the upper layers of the soil, subsisting on protein from dead plants. Eventually, mycologists theorize that the geophilic fungi found themselves on the skin of animals that had rolled in the soil. Those fungi developed the ability to eat the stratum corneum of the animal, becoming zoophilic fungi. Infected animals were domesticated by early humans, and contact with them transferred the fungi to their bodies, where it developed the ability to survive on human stratum corneum, becoming anthropophilic. As most cases of tinea pedis are contracted directly or indirectly from other humans, the organisms responsible for tinea pedis are classified as anthropophilic.

The fungal species most often found to cause tinea pedis are Trichophyton rubrum (60% of cases), Trichophyton mentagrophytes (20%), and Epidermophyton floccosum (10%).5 Less common invaders include Microsporum canis and Trichophyton tonsurans.

Epidemiology of Tinea Pedis
While tinea pedis does not occur to any greater or lesser degree in any specific racial/ethic group, it does demonstrate several characteristic epidemiological features.4

Sports/Recreational Activities: The sports/tinea pedis connection has been permanently linked by the term “athlete’s foot.” One of the reasons for the link between tinea pedis and sports or recreational activities lies in the harsh work the feet are often required to carry out. Running and jumping often cause abrasions of the foot. Soccer, for example, demands that the feet undergo fairly intense and repeated shocks.8 As a result, the athlete’s feet are seldom free of cuts and scratches that could harbor an organism.

However, the patient with a foot abrasion will not contract tinea pedis unless he or she comes into contact with desquamated skin cells infected with a dermatophyte. Thus, a primary epidemiological factor is walking barefoot in any area where the dermatophyte is likely to be found, whether it is carpeted or not.9 Possible locations are saunas, swimming pools, water parks, and shower/bathing facilities. Fungal contact often happens during sports activities, as most athletes prepare and shower in shared locker rooms and shower stalls. Thus, a potential sports-related transmission chain can be hypothesized and used as a model for other cases of tinea pedis. An athlete with active or subclinical tinea pedis walks barefoot in a common area, or showers in a common stall. The next athlete to walk over the infected area may have an abrasion as a result of the sports activity, allowing the organism to invade the pedal epidermis.

Foot Wear : Any clothing that retains sweat does not allow underlying skin to dry. Continually moist skin leads to maceration, in which the skin is damaged and more vulnerable to fungal implantation and growth. This concept leads to an interesting observation with regard to tinea pedis. In societies where wearing shoes is not common, tinea pedis is also uncommon. When “civilization” dictated covering the feet with shoes and socks (especially those made from synthetic materials), tinea pedis began to become common, especially when the prevailing climate was warm and humid.3,10

Some groups are more likely to experience tinea pedis as a result of the sweat-clothing connection. Athletes’ bodies sweat during and after exertion as a thermoregulatory cooling response. Athletes usually wear shoes and socks that allow moisture to remain in contact with the feet. This is a major causal factor in the survival of implanted tinea pedis organisms.8 The incidence of tinea pedis increases greatly following wars in tropical areas, as infected soldiers return to the U.S.10

Gender: Tinea pedis is more common in men than women.4,11 Part of the explanation may lie with the types of footwear considered acceptable in the workplace. Women’s sandals are considered dress attire, so their feet are usually less prone to be bathed in moisture than the man in traditional business dress, requiring socks and shoes that prevent evaporation.12

Age: The age at which tinea pedis occurs is distributed in a unimodal pattern. It is rare in those aged 10 years and under, becomes more common as the patients approach their 20s, and peaks in the 20s and early 30s.7 It becomes steadily less common until patients reach their 60s, when it is again rare.

Case Study

A young man approaches the pharmacist to request assistance in self-treating his athletes foot. He is trying out for the football team, and the coach told them that several of the players had athletes foot last year and cautioned them to inspect their feet and obtain early treatment to avoid spreading the condition. Within the last month, the young man has been increasingly troubled by itching between the fourth and fifth toes. The skin appears dried and white, but it has now broken open and is very painful. Furthermore, the soles of the feet are now pruritic.

This patients symptoms seem to imply possible interdigital tinea pedis. If so, it will likely spread to involve the soles, arches, and heels unless it is promptly treated. The pharmacist might ask to inspect the feet to ensure that they do not have features suggestive of a condition requiring referral (e.g., bacterial or Candidal infection). If not, the pharmacist may choose a nonprescription antifungal agent to cure the condition.

The best choice of therapy is one that produces a cure with the shortest treatment period, such as one week, as opposed to products that cannot cure unless they are applied for two weeks or four weeks. In addition, the more convenient a product is to apply, the greater the chances of compliance and adherence to the dosage regimen. For this reason, a product producing a cure with only one application daily is preferable to one requiring two applications daily. This points the pharmacist toward terbinafine gel as the optimal therapeutic intervention.

The pharmacist should also provide information on prevention of future episodes. The young man should be cautioned against walking barefoot in the locker room or shower stalls. He should also be instructed to keep the feet as clean and dry as possible. With full attention to these tips and others provided above, he might never suffer another episode of tinea pedis.

Concomitant Dermatophytic Infection
A common clinical finding in patients with tinea pedis is the simultaneous presence of a tinea at another location on the body. This is probably the result of autoinfection, in which a patient with a tinea fails to take proper preventive advice and subsequently allows it to reach uninfected skin, hair, or nails. In one study of infected patients with tinea pedis, 20% also had nail infection, and 10% also had tinea corporis.7 This finding underscores the wisdom of heeding the preventive advice and seeking prompt treatment of an existing tinea infection.

Hyperhidrosis: Hyperhidrois is excessive sweating of the feet. Since maceration of the feet is a major contributing factor to fungal inoculation, survival, and growth, it should be evident that excessive sweating would predispose to tinea pedis. 9

Manifestations of Tinea Pedis
Tinea pedis infections exist across a spectrum. Some tinea pedis infections are subclinical.8 In these cases, the patient is generally unaware of the infection until a physician carries out a routine examination and discovers a slight irregularity that is clinically diagnosed as tinea pedis. Symptomatic tinea pedis is traditionally placed into one of three classifications (interdigital, moccasin, and vesiculobullous). The categories are differentiated on the basis of location and appearance.

Interdigital: Interdigital tinea pedis, the most common subtype, is usually caused by Trichophyton rubrum or by Trichophyton mentagrophytes; Epidermophyton floccosum may also be the cause.12,13 As the name implies, interdigital tinea pedis can occur between any of the toes, but the most frequent site is the interspaces of the fourth and fifth toes.10 This follows the generally observed finding that tinea preferentially invades intertriginous skin. As one places the foot into socks and shoes, the toes with the greatest area of overlapping surface contact are usually the fourth and fifth toes. Thus, the risk of skin damage and maceration is higher in that interdigital space.

The interdigital skin infected with this type of tinea pedis often appears dried, dead, and white, with visible peeling. Beneath the peeled area, the skin is reddened. The patient complains of itching and painful fissures.10

Interdigital tinea pedis may be the initial implantation point of tinea pedis, and the beginning of a large-scale tinea foot invasion, spreading outward to cover the other surfaces of the toes, the soles, arches, and heels.

Interdigital tinea pedis is subdivided into two subcategories. The less severe is dermatophytosis simplex, a chronic scaling condition. However, if the patient occludes the web spaces, Gram-negative organisms can complicate the picture, facilitating the development of maceration, causing inflammation, and producing a foul odor. 7 This is known as dermatophytosis complex.10

Moccasin: Moccasin tinea pedis is also known as hyperkeratosis tinea pedis, and is usually caused by Trichophyton rubrum.10 It is diagnosed when tinea affects the parts of the foot normally covered by a moccasin, such as the totality of the plantar surfaces (soles and heels), and the sides of the feet. The lesions are fine, diffuse and hyperkeratotic white scales with a border that seems to meander randomly like a river’s course.9,10 Underlying skin is pink to red.13 The patient complains that the affected areas are tender and pruritic. A more severe form can occur, with the skin fissuring and becoming erythematous, odorous, and inflamed.12 With constant scratching, the patient can transfer tinea to the hand, which is known as tinea manuum. As many patients have a “dominant” hand they predominantly use for scratching, tinea manuum may only be unilateral. For this reason, the condition is often termed, “two-foot, one-hand” disease.” 9

Moccasin tinea pedis is a chronic condition that may not respond well to certain topical antifungals. Quite often, the patient has a concomitant onychomycosis that is the focus for reinfection; the nail infection must also be treated to halt recurrences. 10

Vesiculobullous: The vesiculobullous form of tinea pedis is usually a result of poorly treated or untreated interdigital tinea pedis. The most common causal agent is Trichophyton mentagrophytes.13 The patient discovers that the instep and/or sole of the foot have developed vesicles that occasionally fuse to form large bullae, but more often develop into flat red macules.9,10 The infection is inflammatory and pruritic.9 It is the least common subtype of tinea pedis, but also the most severe. 12

Recognizing Tinea Pedis
Physician Diagnosis: If necessary, a physician can carry out a simple test for confirmation of the presence of tinea pedis. A wet-mount with potassium hydroxide 10% to 20% followed by direct microscopy reveals the fungal hyphae.2,10 A lab may also grow fungi on a suitable medium.

Pharmacist Recognition: Tinea pedis is one of the dermatological conditions that the pharmacist can assist the patient in treating effectively by selecting the most appropriate over-the-counter (OTC) product after careful inspection. If the condition’s manifestations appear to match those previously discussed, the pharmacist might recommend a course of nonprescription antifungals, suggesting a product that is maximally convenient for the patient to use and capable of producing a cure with a minimum number of applications.

Conditions Resembling Tinea Pedis: Several conditions can mimic the appearance of tinea pedis ( TABLE 1). They include fungal infection with Candida albicans (erosio interdigitalis blastomycetica) or Scytalidium dimidiatum, and bacterial infection by Corynebacterium minutissimum (erythasma) or Gram-negative invaders.9-11,14 Bacterial infections are usually limited to the interdigital spaces; if the infection is due to Gram-negative organisms, common features include odor, pus, and a yellowish-green color. 11

The patient may also have pustular psoriasis.9,11 Psoriatic lesions of the foot usually occur only over the pressure points, e.g., points of contact between the foot and shoe, where epidermal abrasion can induce the koebner phenomenon (skin lesions appearing on a site of trauma). These lesions are symmetrical and have sharp margins with a flaking, micai-like surface. The patient often has pitted and thickened toenails, as well as lesions on the scalp, elbows, and knees.11

Dyshidrotic eczema may be the culprit as well; it is a recurrent noninflammatory eruption that is more common during warm weather. The patient with dyshidrotic eczema experiences a sudden onset of symmetrical blisters on the soles (high instep) and sides of the toes.9,11 The blisters often coalesce and weep upon rupture, and the skin peels as the condition resolves over a two- to three-week period. The soles are not reddened and scaly as in tinea pedis. If any of these problems are possible, the patient should be urged to seek care from a primary care physician or podiatrist.

Contact dermatitis to materials in shoes (e.g., rubber insoles, dyes, tanning agents) can also resemble tinea pedis.11 An important diagnostic parameter of shoe dermatitis is the presence of normal skin in which the foot is not in contact with the shoes. In this instance, the area affected is usually the arch, rather than the highly callused sole; the toe webs are not affected and the nails will be normal. If the problem is contact dermatitis, the pharmacist could suggest wearing different shoes and application of hydrocortisone 1% cream. If this fails to resolve the problem, the patient should seek care from a physician.

Table 1
Conditions Resembling Tinea Pedis9,14

Condition

Remarks

Nontinea fungal infection Organisms include Candida albicans and Scytalidium dimidiatum
Bacterial infections Usually limited to interdigital spaces
Pustular psoriasis Symmetric lesions, over the pressure points, with sharp margins; involvement of toenail probable
Dyshidrotic eczema Symmetrical blisters on soles and side of toes; soles are not red
or scaly; more common during warm weather
Contact dermatitis Common location where foot is in close contact with shoe or
sock; sole and toe webs seldom affected; nails normal

Potential Sequelae of Untreated/Poorly Treated Tinea Pedis
Chronic Infection: Should tinea pedis be improperly or inadequately treated, the patient will undoubtedly experience a chronic condition. This is because the fungus thrives only in dead tissues, where some of the body’s most valuable antimicrobial defenses (e.g., antibodies, phagocytic reactions) are not operative. Typically, tinea pedis enters a quiescent stage during the cold winter months. 7 However, even though symptoms appear to have abated, the inability of the body to eradicate it ensures that it will arise again when conditions are more favorable. Usually, as the ambient temperature rises and the feet begin to sweat, the organism emerges from dormancy and the symptoms begin anew. It is common for the chronically infected patient to complain of recurrent tinea pedis, with the recurrences coinciding with the onset of spring and summer, and quiet periods being the late fall and winter.

Autoinfection: Another common sequelae of poorly or inadequately treated tinea pedis is transfer to other body sites. Tinea pedis may be the nidus of infection from which the patient develops tinea unguium, tinea corporis, tinea cruris, tinea pedis, or any of the other potential dermatophytic cutaneous infections. The longer the infection is present, the greater the potential for spread to unaffected sites.

Dermatophytic Reactions: Patients with an existing tinea infection may experience eruptions at distant sites that are not caused by the spread of the initial infection.9 This process is referred to as a dermatophytid or “id” reaction. When patients develop fungal id infections on the arms, chest, or sides of the fingers, the toe webs should be closely examined for the presence of a symptomatic or subclinical infection that must be treated.10

Dermal and/or Subcutaneous Extension: A complication of poorly treated tinea pedis is extension of the dermatophyte into deeper tissues, possibly resulting from local suppression of lymphocyte blastogenic response by the dermatophytes.2 Should the tinea invade subcutaneous tissue, it can produce a subcutaneous abscess and ulceration. 2 This complication is seen in several patient groups (who are more prone to develop deep abscesses that ulcerate):
•Patients with systemic immunosuppression.
•Atopic patients (an immediate hypersensitivity reaction may hamper development of delayed immunity).
•Patients with diabetes, with decreased ability to perceive the presence of the infection due to neuropathy.

Bacterial Superinfection: At times, foot damage due to a tinea infection (e.g., fissuring of the skin on the soles or between the toes) may facilitate the growth of a bacterial superinfection.10 Bacterial infection of the foot due to tinea is a particularly acute danger to the patient with diabetes, as the majority of limb amputations in this population can be directly traced to a bacterial foot infection. For this reason, the patient with diabetes must act quickly to ensure that the tinea infection is treated appropriately.

Prevention of Tinea Pedis
In order to prevent tinea pedis, the patient can focus on the factors that increase the risk of contracting it, and avoid or eliminate them. For instance, if anyone in the house has tinea pedis, other household residents should wear foot protection in the shower and not use towels or wash cloths that the index patient may have used until they are thoroughly laundered. Furthermore, a patient with an existing tinea infection elsewhere on the body should use a different towel on the feet to avoid transfer. Further tips for prevention will be discussed later in this article.

When Patient Referral is Required
The pharmacist should refer the patient to a primary care physician or podiatrist if there is lack of assurance that the problem is tinea pedis (or any other minor, self-treatable foot condition). The pharmacist may use the manifestations previously presented to help recognize tinea pedis.

Nonprescription, OTC antifungal product labels contain clear instructions for when the patient should stop use and see a physician (e.g., if excessive irritation occurs or if irritation worsens). The packages are also labeled with the duration of treatment before the patient should expect a cure. While this time period varies with each specific product, the patient should be aware that persistence of suspected tinea pedis might indicate that another condition is the cause of the symptoms and a physician diagnosis should be sought.

Nonprescription Treatment Options
Topical antifungals are commonly used to treat tinea pedis. They are available in several dosage forms, but this fact does not present serious counseling problems to the pharmacist. The reason is that dosage form is a strong determinant of efficacy, so that some products are only available in the most effective dosage form(s). Therefore, choosing a dosage form is not nearly as important as choosing the best ingredient. A few clues can be gleaned from the medical literature. Gels are effective in drying moist toe web spaces, and a newly introduced gel is now the most efficacious dosage form, when available products are classified by duration of treatment and fewest number of daily applications required.10 Creams are helpful on dry, scaly, moccasin-type tinea pedis. Powders are helpful when dusted inside shoes, although the most effective ingredients are not available in powder form.

One reference suggests that when applying a topical antifungal, the patient should ensure that the area is covered, including about an inch beyond the margins of visible infection.2 Another suggests applying the antifungal in a 1.5 to 2.5 inch radius around the site of itching as soon as pruritus begins.4 Applying the product beyond the visible sites of infection might boost the success rate and lower the risk of recurrences. These references suggest that treatment continue for at least one to two weeks beyond the time that the condition is apparently cured. During treatment, patients should strive to wear nonocclusive footwear and alternate shoes daily to allow them a “resting period” to dry out thoroughly between wearing.12

Therapeutic Options Classified by Duration of Treatment and Number of Daily Applications
The nonprescription antifungal market has seen several waves of products appear, each with increasingly compelling advantages to its use ( TABLE 2). Prior to the early 1970s, there was little choice among effective nonprescription tinea pedis treatments. Undecylenic acid and its salts was the most effective therapy until tolnaftate was switched from prescription to OTC in 1971. This was followed by OTC switches of two imidazoles: miconazole in 1982 and clotrimazole in 1989. These will be referred to as the first-generation nonprescription antifungals, as they share important common attributes. (Since the marketing of undecylenic acids and their salts has been largely discontinued in most top-selling product lines, they will not be discussed further.) A second generation of products appeared with the prescription-to-OTC switches of terbinafine in 1999 and butenafine in 2001. The second-generation antifungals shared critical differences when compared with the first-generation products. A third-generation product with an important therapeutic advantage over previous agents has also been introduced.15

Table 2
Summary of Selected FDA-Approved Nonprescription Antifungals16

Ingredient

Dosage Form(s)

Select OTC
Product(s)

Age Cut-off

Daily Treatments Required

Location and
Treatment Duration

First-Generation Antifungals
Clotrimazole Cream Cruex Cream, Lotrimin AF Cream 2 years Two All locations; 4 weeks
Miconazole Cream, powder, spray liquid, spray powder Cruex Spray Powder, Desenex Powder, Lotrimin AF Powder, Micatin Spray Liquid, Neosporin AF Cream 2 years Two All locations; 4 weeks
Tolnaftate Cream, powder, spray liquid, spray powder Aftate Spray Liquid, Lamisil AF Defense Powder, Tinactin Cream and Spray 2 years Two All locations; 4 weeks
Second-Generation Antifungals

Butenafine

Butenafine

Cream

Cream

Lotrimin Ultra Cream

Lotrimin Ultra Cream

12 years

12 years

Two

One

Between the toes;
1 week

Between the toes; 4 weeks

Terbinafine Cream, solution, spray pump Lamisil AT Cream, Spray Pump, Solution 12 years Two Between the toes; 1 week. Bottom and sides of feet; 2 weeks (cream only)
Third-Generation Antifungal
Terbinafine Gel Lamisil AT Gel 12 years One Between the toes; 1 week

First-Generation Antifungals: First-generation antifungals carry labeling stating that they cure athlete’s foot in patients aged two years and above, without differentiating among the three common subtypes of tinea pedis. They are also characterized as having the longest duration of treatment required of any nonprescription antifungals. This may be caused by their questionable ability or inability to kill the fungi outright. Tolnaftate may exert fungicidal effects, but it may only be fungistatic.16 The imidazoles are not fungicidal under any circumstances. Rather, they are fungistatic, as they only hamper development of the fungal cell membrane.2 All are labeled as requiring four weeks of use twice daily for best results. This presents serious problems in achieving a cure, as the average period of time patients will self treat tinea pedis is only 7.3 days.17 The only significant therapeutic difference among the first-generation antifungals is that tolnaftate is proven effective in preventing recurrences of tinea pedis. However, yearly recurrences of the same infection, by definition, indicate that the product chosen the previous year was ineffective in eradicating the fungal invader, clearly a treatment failure. The patient should be urged to seek a more effective fungicidal treatment that can prevent the recurrence in the first place.

First-generation antifungals include those containing tolnaftate (e.g., Aftate Spray Liquid, Lamisil AF Defense Powder, Tinactin Cream and Spray), miconazole (e.g., Cruex Spray Powder, Desenex Powder, Lotrimin AF Powder, Micatin Spray Liquid, Neosporin AF Cream), and clotrimazole (e.g., Cruex Cream, Lotrimin AF Cream).

Second-Generation Antifungals: The second-generation antifungals are characterized by a shorter duration of treatment for tinea pedis and a higher age at which they are safe for self-use. They are not recommended for use by patients below the age of 12 years. Terbinafine is a fungicidal allylamine antifungal. It is marketed as Lamisil AT Cream, Spray Pump, and Solution.17 All three dosage forms cure interdigital tinea pedis if used twice daily for one week. If the patient has tinea pedis on the bottom and/or sides of the foot (e.g., moccasin or vesiculobullous varieties), the only dosage form with proven efficacy is the cream, when used as directed twice daily for two weeks. Butenafine is a synthetic fungistatic/fungicidal benzylamine antifungal available as Lotrimin Ultra Cream, which will cure interdigital tinea pedis if used twice daily for one week or once daily for four weeks.18,19 Its efficacy on the bottom and sides of the feet is unknown, and it is not allowed to carry an indication for moccasin or vesiculobullous tinea pedis. Second-generation agents are not available as powders.

Third-Generation Antifungal: A third-generation antifungal has recently been marketed, Lamisil AT Gel, containing the fungicidal allylamine terbinafine.20 It will achieve cure of tinea pedis between the toes in patients aged 12 and above if applied once daily for only one week (efficacy on the bottom or sides of the foot is unknown). Its shorter treatment regimen arises from the fact that it is highly lipophilic and keratophilic and maintains high therapeutic levels in the skin for an additional seven days after once-daily application for seven days.20-23

There is a significant advantage to once-daily application. Products that require twice-daily application for one week to cure rely on patient diligence in carrying out these applications. However, the target patient is often a male adolescent athlete. This group may feel that they have many more pressing matters to remember (e.g., work,school, dating) than two administrations of a topical medication. The reality of life is that compliance plummets as the number of medication administration episodes multiplies.17 A product that requires two daily applications cannot be fully effective if the patient can only manage one application most of the time. Thus, any product that produces a cure for tinea pedis with only one daily application possesses a significant advantage in patient adherence to the dosage regimen. Finally, increased adherence to the dosage regimen producing a complete cure is significantly advantageous in preventing yearly recurrences from the same, poorly treated infection.17

Products/Interventions to Avoid
Unfortunately, many Web sites and companies irresponsibly market unproven remedies for tinea pedis. One promoting an ointment promises to relieve pain and itching associated with minor skin irritations. Their Web site features information about tinea pedis, implying that the product is approved for tinea pedis indication.24 However, the product contains camphor 1.24%, methyl salicylate, salicylic acid, and benzoic acid (concentrations unlabeled). 25 None of these are proven safe and effective for the treatment of tinea pedis. Furthermore, the erosive effect of salicylic acid is counterproductive in tinea pedis and external analgesics such as camphor and methyl salicylate are contraindicated for use on broken skin, such as that seen in interdigital tinea pedis.11 Its use could prevent the patient from purchasing and using a more appropriate antifungal product.

A search of a Web site featuring popular homeopathic treatments demonstrates other unproven medications being promoted for tinea pedis. Depending on exactly which symptoms the patient enters on a purported matching remedy finder, the company recommends diluted silicea, causticum, or sepia.26-28 None of these diluted remedies is proven safe or effective when applied to tinea pedis.

Other Web sites promote such unproven products/ingredients as silver-impregnated antibacterial socks, methyl sulfonyl methane, white sulfur, benzalkonium chloride, and herbs such as garlic and tea tree oil.29-32 None of these have been proven safe and effective as an antifungal, using FDA approval as the ultimate and well-accepted scientific criterion. When the pharmacist is confronted with unknown remedies such as these, it is prudent to call a company representative and ask for copies of correspondence with the FDA demonstrating that the product is safe and effective. In the absence of such data, it is safe to assume that the remedy is unproven. These manufacturers often speak vaguely about “clinical studies,” which they have neglected to provide to the FDA. The quality of these studies is in question until the FDA issues a ruling after careful study.

Some irresponsible Web sites allow lay people to provide their own unproven home remedies for tinea pedis. On one such Web site (sponsored by a homeopathic company), people tout the benefits of such diverse and unproven therapies as application of thuja, graphite, selenium, rubbing alcohol, and neem oil, as well as urinating on one’s own feet while showering.33 Patients using these unproven products, especially those derived from natural substances such as propolis, risk adverse reactions, including allergic contact dermatitis.34

Strategies for Educating, Counseling, and Enhancing Adherence
Approaching the Patient: The pharmacist who wishes to assist patients in treating tinea pedis must accomplish several tasks. First, he or she must be cognizant of the condition’s appearance in order to properly triage the patient. Next, the pharmacist must have a full grasp of the various topical nonprescription products available. Finally, the pharmacist must not hesitate to approach patients who appear to be examining the tinea pedis products.

Some pharmacies have prescription workloads that do not allow the pharmacist to engage in vital tasks such as counseling on self-care with OTC products. Other pharmacies have architectural designs that do not allow visualization of the nonprescription product aisles. In these cases, the pharmacist may choose to walk up and down the self-care aisles when there is a lull in prescription filling. For pharmacies that are more conducive to patient counseling on self-care issues, the pharmacist’s potential to help patients with tinea pedis is enhanced.

The pharmacist can strive to meet several important informational goals when counseling the patient with tinea pedis, such as helping the patient choose a product with a simple application regimen, counseling on prevention of future episodes, and helping the patient understand why it is critical to avoid unproven products.

Choose A Product With Fewest Number of Applications: When choosing a product for tinea pedis, the pharmacist should keep in mind that patients will often prematurely discontinue products with a longer treatment regimen. Thus, a product with a one-week treatment duration would be preferable to a two- or four-week product. As many patients may be unable to comply with a twice-daily application regimen, products with only once-daily application are also more likely to produce a cure.

Counseling on Prevention of Future Episodes: Patients should be advised to wear nonocclusive footwear such as sandals as frequently as possible, but especially in the summer.35 Those who must wear shoes and socks during the day, such as business professionals, should be advised to wear cotton socks and leather shoes that “breathe” and reduce sweating.4,13 They should also change to sandals as soon as they can and wear them until bedtime. They may also go barefoot as often as they can around the house (with the exception of diabetic patients with peripheral neuropathy).4 Socks should be laundered after each wearing in the hot cycle of the washer and thoroughly dried in the hot cycle of the dryer before wearing again.4 Athletic shoes also may be sprayed with disinfectants and/or treated with bleach to destroy fungi.

During the bath or shower, patients must wash the feet and toes carefully each day.4 Patients should be taught to dry the feet thoroughly after each bath or shower, paying closer attention to the interdigital spaces.12 The towels and washcloths used should be freshly washed. The patient should never use a towel borrowed from another person or found in a communal bathing/changing room. 4 Furthermore, the towel used to dry the feet should never be used subsequently to dry the trunk or groin, as tinea can be transferred to those areas.

Patients should also be advised to wait for 10 to 15 minutes after bathing to don socks and shoes to help the feet dry. The goal is to have the feet completely dry at all times other than when bathing.

Counseling the Patient to Avoid Unproven Products: When pharmacists are counseling patients about self-treatable conditions, professional ethics and moral responsibility dictates that they should take every opportunity to caution the patient against using unproven products. In the case of tinea pedis, the spectrum of unproven products is wide, consisting of the almost universally unproven realm of homeopathic products, herbals, and dietary supplements. It also encompasses numerous home remedies that are equally unproven and which should likewise be avoided. Rather, the patient should be urged to choose products with FDA-proven safety and efficacy.

Conclusion
Tinea pedis is a common dermatophytic infection that affects millions worldwide. There are several types of tinea pedis and numerous conditions that mimic the infection, thus it is important to properly diagnose it. The pharmacist who engages patients in self-care counseling regarding nonprescription products for tinea pedis can educate them on how to avoid becoming infected, as well as teach them how to avoid recurrences. As a result, patients will be more likely to choose products that will yield a complete and rapid cure of the condition, with a high likelihood that they will adhere to the dosage regimen.

References
1. Mahmoudabadi AZ. A study of dermatophytosis in South West of Iran (Ahwaz). Mycopathologia. 2005;160:21-24.
2. Erbagci Z. Topical therapy for dermatophytoses: Should corticosteroids be included? Am J Clin Dermatol. 2004;5:375-384.
3. Woodfolk JA. Allergy and dermatophytes. Clin Microbiol Rev. 2005;18:30-43.
4. What you need to know about tinea pedis. Nurs Times. 2004;100(30):33.
5. US Food and Drug Administration. Natural history of tinea pedis. Available at: http://www.fda.gov/ohrms/dockets/ac/04/briefing/4036B1_04_Natural%20History%20of%20 Tinea%20Pedis.htm. Accessed February 20, 2007.
6. Savin R, Jorizzo J. The safety and efficacy of sertaconazole nitrate cream 2% for tinea pedis. Cutis. 2006;78:268-274.
7. Welsh O, Welsh E, Ocampo-Candiani J, et al. Dermatophytoses in Monterrey, Mexico. Mycoses. 2006;49:119-123.
8. Purim KS, Bordignon GP, Queiroz-Telles F. Rev Iberoam Micol. 2005;22:34-38.
9. Loo DS. Cutaneous fungal infections in the elderly. Dermatol Clin. 2004;22:33-50.
10. Tan JS, Joseph WS. Common fungal infections of the feet in patients with diabetes mellitus. Drugs Aging. 2004;21:101-112.
11. Topical antifungal drug products for over-the-counter human use: establishment of a monograph. Fed Regist. 1982;47:12480-12566.
12. Gupta AK, Cooper EA, Ryder JE, et al. Optimal management of fungal infections of the skin, hair, and nails. Am J Clin Dermatol. 2004;5:225-237.
13. Gupta AK, Ryder JE, Chow M, Cooper EA. Dermatophytosis: the management of fungal infections. Skinmed. 2005;4:305-310.
14. Adams SP. Dermacase. Canadian Family Physician. Available at: http://www.cfpc.ca/cfp/2002/Feb/vol48-feb-clinical-2.asp. Accessed February 2, 2007.
15. Pray WS. Fungal skin infections. Nonprescription Product Therapeutics. Baltimore, MD: Lippincott Williams & Wilkins; 2006:584-596.
16. McEvoy GK, ed. AHFS Drug Information 2006. Bethesda, MD: American Society of Hospital Pharmacists; 2006:3433.
17. Department of Health and Human Services. US FDA. Center for Drug Evaluation Research. Nonprescription Drugs Advisory Committee in joint session with the Dermatologic and Ophthalmic Drugs Advisory Committee. May 6, 2004. Available at: http://www.fda.gov/ohrms/dockets/AC/04/transcripts/4036T1.DOC. Accessed February 2, 2007.
18. Mentax (butenafine HCl cream) cream, 1% package insert. Morgantown, WV: Bertek Pharmaceuticals Inc; June 2001. Available at: http://www.fda.gov/cder/foi/label/2001/20524s5lbl.pdf. Accessed February 2, 2007.
19. Reyes BA, Beutner KR, Cullen SI, et al. Butenafine, a fungicidal benzylamine derivative, used once daily for the treatment of interdigital tinea pedis. Int J Dermatol. 1998;37:450-453.
20. Hollmen KA, Kinnunen T, Kiistala U, et al. Efficacy and tolerability of terbinafine 1% emulsion gel in patients with tinea pedis (Letter). J Eur Acad Derm Venereol. 2002;16:87-88.
21. van Heerden JS, Vismer HF. Tinea corporis/cruris: new treatment options. Dermatology. 1997;194(suppl 1):14-18.
22. Denouel J, Burtin P, Kshatriya B, Snoddy A. Pharmacokinetics of terbinafine 1% emulsion gel in healthy volunteers and in patients with tinea cruris/corporis. Paper presented at: 2006 AACP Annual Meeting; October 26, 2006; St. Louis, MO. Abstract 248. Available at: http://www.pharmacotherapy.org/pdf/free/pharm2610_accpabstracts.pdf. Accessed February 2, 2007.
23. Cramer J, Kshatriya B, Snoddy A. Skin pharmacokinetics of terbinafine in healthy subjects following once-daily application of 1% emulsion gel or 1% cream for 1, 5, or 7 days. Paper presented at: 2006 AACP Annual Meeting; October 26, 2006; St. Louis, MO. Abstract 249. Available at: http://www.pharmacotherapy.org/pdf/free/pharm2610_accpabstracts.pdf. Accessed February 2, 2007.
24. Blue Star Ointment. Product info. Athlete’s foot. Available at: http://www.bluestarointment.com/index2.html. Accessed February 2, 2007.
25. Blue Star Ointment. Product and medical information. Ingredients. Available at: http://www.bluestarointment.com/index2.html. Accessed February 2, 2007.
26. ABC Homeopathy. Treatment for extremities, limbs; skin; itching; foot; back of foot. Available at: http://www.abchomeopathy.com/go.php. Accessed February 2, 2007.
27. ABC Homeopathy. Treatment for extremities, limbs; perspiration; foot; sole; itching. Available at: http://www.abchomeopathy.com/go.php. Accessed February 2, 2007.
28. ABC Homeopathy. Treatment for extremities, limbs; skin; itching; foot. Available at: http://www.abchomeopathy.com/go.php. Accessed February 2, 2007.
29. Healthy Channels. Smelly feet no more. Available at: http://www.smellyfeetnomore.com/?gclid=CIiy-Y22kIoCFRLTgAodkT3LhQ. Accessed February 2, 2007.
30. DermaTech Rx. Don’t let athlete’s foot walk over you. Available at: http://www.dermatechrx.com/AthletesFoot/. Accessed February 2, 2007.
31. Loyola University Health System. Tinea pedis. Available at: http://www.luhs.org/health/ kbase/htm/mdx-/amm0/096/mdx-amm0096.htm. Accessed February 2, 2007.
32. PeaceHealth. Athlete’s foot. Available at: http://www.peacehealth.org/kbase/cam/ hn-1014004.htm. Accessed February 2, 2007.
33. ABC Homeopathy. Homeopathy and health forum. Athlete’s foot. Available at: http://www.abchomeopathy.com/forum2.php/1134/. Accessed February 2, 2007.
34. Lee SY, Lee DR, You CE, et al. Autosensitization dermatitis associated with propolis-induced allergic contact dermatitis. J Drugs Dermatol. 2006;5:458-460.
35. National Library of Medicine. Athlete’s foot. Available at: http://www.nlm.nih.gov/ medlineplus/ency/article/000875.htm. Accessed February 2, 2007.

 


December 2008
accutane acomplia
e-CONNECT Newsletter
US Pharmacist's e-CONNECT Newsletter
View e-CONNECT Newsletter

 
Pharmacists
About USPharmacist
Article Archive
CE Author Guidelines
Non-CE Author Guidelines
Classifieds/Career Center
Contact Us
Conventions Calendar
Links
Patient Teaching Aids
Subscribe

 

b Early Versus Delayed Diagnosis and Treatment of Parkinson’s Disease: What You Need to Know
This activity is supported by an educational grant from Teva Neuroscience.
b Identifying Factors That Cause Pharmacy Errors
2.0 Credits, Expires: 12/31/2010 **Payment is required for exam to be graded.
b Approved and Unapproved Hydrocodone-Containing Cough Products: What Do You Need To Know?
This activity is supported by an educational grant from UCB.
b New Guidelines for the Diagnosis and Management of Asthma
2.0 Credits, Expires: 10/31/2010 **Payment is required for exam to be graded.
b Demystifying: Type 2 Diabetes Management
This activity is supported by an educational grant from Takeda Pharmaceutical North America, Inc.
b The Pharmacist’s Role in the Appropriate Selection of a Nonprescription Product for Pain Relief
This activity is supported by an educational grant from Hisamitsu America, Inc.
b Pharmacists: Are Your Drug Information Databases Accurate?
This activity is supported by an educational grant from Teva Neuroscience.
b The Treatment of Benign Prostatic Hyperplasia
2.0 Credits, Expires: 8/31/2010 **Payment is required for exam to be graded.
b Conquering IBS in Women: The Clinician's Pursuit of Optimum Management Strategies
This activity is supported by an educational grant from Sucampo Pharmaceuticals, Inc and Takeda Pharmaceuticals North America, Inc.
b Newer Approaches to the Long-Term Management of Dry Eye Disease
This activity is supported by an educational grant from Allergan.
b Total Cholesterol Management: Taking Complete Control
This activity is supported by an educational grant from Merck & Co., Inc.
b Delirium in the Elderly: Medications, Causes, and Treatment
2.0 Credits, Expires: 6/30/2010 **Payment is required for exam to be graded.
b The Use of Saline Nasal Irrigation in Common Upper Respiratory Conditions
This activity is supported by an educational grant from Med-Systems, Inc.
b Newer Insights Into the Prevention of the Common Cold
This activity is supported by an educational grant from Procter & Gamble.
b Advanced Topics in Medicare Part D: Assisting Patients Eligible for Low-Income Subsidies
This activity is supported by an educational grant from UnitedHealthcare.
 

Celiac Disease: More Common Than Once Thought
The Operating Room Pharmacist and Bariatric Surgery
Adverse Events Associated with NSAIDs
Ulcerative Colitis: Achieving and Maintaining Remission
..
 
Home | Featured Articles | Continuing Education | Subscribe

U.S. Pharmacist is a monthly journal dedicated to providing the nation's pharmacists with up-to-date, authoritative, peer-reviewed clinical articles relevant to contemporary pharmacy practice in a variety of settings, including community pharmacy, hospitals, managed care systems, ambulatory care clinics, home care organizations, long-term care facilities, industry and academia. The publication is also useful to pharmacy technicians, students, other health professionals and individuals interested in health management. Pharmacists licensed in the U.S. can earn Continuing Education credits through Postgraduate Healthcare Education, LLC, accredited by the Accreditation Council for Pharmacy Education (ACPE) as a provider of continuing pharmacy education.

Copyright © 2000 - 2014 Jobson Medical Information LLC unless otherwise noted.
All rights reserved. Reproduction in whole or in part without permission is prohibited.