INTRODUCTION
Tinea pedis is the most commonly encountered superficial
cutaneous fungal infection in humans. In
the United States, the highly contagious Trichophyton
rubrum and Trichophyton mentagrophytes Var interdigitale
are recognized as the primary causative organisms, T.
rubrum accounting for more cases. Epidermophyton floccosum
infects the plantar skin less frequently. Approximately
10 to 20% of the general population has been affected by
tinea pedis. About 70% of these infections are in adults.1 The
natural course of dermatophyte infection eventuates in epidermal
thickening, hyperkeratosis, and scale production. As
with many skin diseases, tinea pedis can impact the patients’
quality of life with symptoms of pruritus, burning, stinging,
discomfort and or pain. Choosing the appropriate antifungal
treatment, systemic or topical, may result in clinical resolution.
However, the disease recurrence rate is high, up to 70%
depending on the source. The reinfection rate is often related
to persisting risk factors, inadequate clearance of the primary
infection and in some cases due to patient noncompliance
with the prescribed therapy.2
Notwithstanding, even with complete eradication of the dermatophyte,
patients often contend that their infection persists
due to the obvious presence of hyperkeratosis. Explaining to
patients that their infection has resolved and that hyperkeratosis
is the skin’s response to the dermatophyte is usually not
well understood and received, even with evidence of a negative
fungal skin culture and mycological cure.
Consequently, the significance of choosing a treatment regimen
that addresses both clearance of active infection and reversal of
hyperkeratosis cannot be underscored and should be strongly
considered when treating this patient population. Furthermore, it is expected that the addition of a keratolytic agent to resolve
the excess horny layer will assist the prescribed topical antifungal
therapy possibly with better penetration, although this
has not been formally measured. With that in mind, we examined
the use of naftifine hydrochloride cream 2% and 39% urea
cream in the treatment of hyperkeratotic tinea pedis.
STUDY DESIGN
We conducted a single center, open-label pilot study. Prior
to initiation of this study, the protocol and informed consent
were reviewed and approved by a central IRB. The purpose of
this study was to examine the use of naftifine hydrochloride
2% cream and 39% urea cream in the treatment of hyperkeratotic
tinea pedis. Eleven male and female subjects 18 years
of age and older clinically diagnosed with mild to moderate
hyperkeratotic tinea pedis on the Investigator Global Assessment
(IGA) scale were enrolled in the study. The IGA scoring
system used to rate current severity of hyperkeratosis was
based on clinical appearance of the disease at the time of assessment
and was graded as follows: 0=clear, 1=almost clear,
2=mild disease, 3=moderate disease, 4=severe disease, and
5=very severe disease. To participate in the study, all subjects
had to understand and sign the informed consent and HIPAA
authorization forms and agree to follow study procedures.
Subjects were screened at the baseline visit and excluded
from the study if they reported participation in an investigational
drug trial within 30 days of their visit, had used any oral
antifungal or steroid medication within 1 month or any topical
antifungal, keratolytic, or steroid treatment within 2 weeks of
their baseline visit, had a medical condition that in the investigator’s
judgment precluded study participation, had a history
of non-compliance or unreliability, or a known history of alcohol
or drug abuse within the past 5 years. All female subjects
