# Presentation: 696562

## Tinea PedisNatural History&Clinical Trials

- Joseph Porres, M.D., Ph.D.
- Medical Officer, DDDDP

## Part I: Natural History

- Tinea pedis subtypes
- Causative organisms
- Dermatomycosis syndrome
- Predisposing factors
- Complicating factors & Complications
- Epidemiology & recurrence
- Diagnosis
- Treatment

## Tinea Pedis Subtypes

- Interdigital: pruritus, erythema, scaling, fissuring, 			maceration
- Plantar:
-  Moccasin: scaling, pruritus, erythema
-  Vesicobullous: pruritus, vesicles, scaling, erythema
- Combinations of interdigital and plantar
- Athlete’s foot is the layman’s term and can be found in reference to any of these forms

## Causative Organisms

*Trichophyton rubrum *(60-80%)
- Plantar, mocassin
- Plantar small vesicles, may also affect distal subungual nail, other body sites
*Trichophyton mentagrophytes* (10-20%),
- Peri-plantar large vesicles, and may spread to white superficial nail
*Epidermophyton floccosum *(3-10%)

## Tinea Pedis Interdigitalis

- Dermatlas, JHMI.EDU

## Tinea Pedis Plantaris

**Rebell, G. & Zaias, N. Cutis 2001, 67, 5S, 6-17**

## Tinea Pedis Plantaris, Vesicular

- Dermatlas, JHMI.EDU

## Tinea Pedis Plantaris, Moccasin

**Rebell, G. & Zaias, N. Cutis 2001, 67, 5S, 6-17**

## Rebell, G. & Zaias, N. Cutis 2001, 67, 5S, 6-17

**Rebell, G. & Zaias, N. Cutis 2001, 67, 5S, 6-17**

## Predisposing Factors

-    Public baths, swimming pools
-    Local trauma on dermatophyte carrying individual
-    Occlusive footgear
-    Immersion
-    Warm weather
-    Exposure to hair of infected animals (rats in Vietnam)
-    Infected family members (~17% in one study)
-    Familial predisposition

## Complicating Factors:

-  Atopy
-  Diabetes
-  Compromised circulation
-  Localized trauma
-  Geriatric population

## Complications:  Cellulitis 

-  Treatment not given
-  Treatment is inadequate
-  Reinfection from the nail

- Complications:  Cellulitis** **

##  Epidemiology 

-  15-70 % of population at large
-  40 % of patients attending a general clinic
-  Those seeking help often have nail involvement
-  Many undiagnosed cases
-  Dermatophytes isolated from:
-  2-40% “normal feet”
-  Public showers
-  Swimming pools
-  Shoes and Socks

## Recurrence

- Topical terbinafine and clotrimazole in interdigital tinea pedis: A multicenter comparison of cure and relapse rates with 1- and 4- week treatment regimens.
- 		Bergstresser PR et al, JAAD 1993; 28: 648-51
- Long-term outcome of patients with interdigital tinea pedis treated with terbinafine or clotrimazole.
- 		Elewski, B. et al. JAAD 1995; 32:290-2

## Study Details

- 193 evaluable patients with interdigital tinea pedis
- Treatment twice daily with:
- terbinafine cr or clotrimazole cr
- 1 or 4 weeks
- Observation for up to 18 months [Elewski]
- Mycology “Cure”** **

## Study Results

## Diagnosis

**Clinical:** by clinical signs and symptoms
**Mycology:** KOH (direct examination) and culture.
- Mycology [KOH] helps confirm diagnosis and avoid:
-  Delay of indicated treatment
-  Prescribing inappropriate treatment

## Treatment.   Efficacy rates reported*:

| Antifungal | Dosage  | Weeks | Rate % | Type of Cure |
| --- | --- | --- | --- | --- |
| Terbinafine | BID | 4 | 97 | Mycology |
| Terbinafine | - | 1 | 76 | Mycology |
| Terbinafine | - | 1 | 97 | - |
| Clotrimazole | BID | 4 | 83 | Mycology |
| Clotrimazole | BID | 1 | 35 | - |
| Miconazole | - | 4 | 87 | - |

- * Treatment of Skin Disease. Lebohl, M. et al, Mosby. 2003

## Part II:  Clinical Trials

**Part II:  Clinical Trials**

- Dose ranging studies
- Clinical trials for safety and efficacy

## Dose Ranging Studies For Tinea Pedis

- Dose ranging studies for topical antifungals often recommended by FDA but usually not conducted
- _Dose ranging studies_ for topical antifungals to select the best safety/efficacy dose:
- Drug strength
- Frequency of application
- Duration of treatment

## Clinical Safety and Efficacy Trials 

- Assessment
- Outcomes

## Assessment

- Mycology:
- Direct microscopic examination (KOH)
- Mycology culture
- Clinical.  Signs and symptoms:
- Erythema
- Scaling
- Pruritus, etc.

## Outcomes

**Outcomes**

-  Mycology “Cure” (MC):
- Negative KOH and negative culture
-  Effective treatment:
- MC, no symptoms, only residual signs
-  Complete Cure:
- MC, and no signs or symptoms

## Clinical Safety and Efficay Studies

**Inclusion/exclusion criteria** often do not  mimic the populations expected to actually use  the product
**Include:** healthy patients with interdigital tinea pedis
**Exclude **harder cases:
- Onychomycosis
- Mocassin type, keratotic feet
- Diabetic
- Immunosuppressed
- Compromised circulation