GD — Society for Dermopharmacy

Issue 1 (2003)

Dermatotherapy
Treatment of Mycosis Pedis by Means of Topical Antimycotics:
The Basis is Likewise Important For a Successful Therapy

There is obviously a much higher incidence of mycoses pedis than presumed to date. A great European study, the so-called Achill-Project revealed that there are indications for the presence of foot and/or nail mycoses at every third person. Mycoses pedis thus belong to the numerically most significant infectual diseases. For the treatment mainly topical antimycotics on the basis of very differing active ingredients and presentation forms are used. Professor Dr. med. Christian Korting, Munich, explained in a conversation with DermoTopics which criteria are to be considered when selecting and applying topical antimycotics. Korting is vice-president of the GD - Society for Dermopharmacy and secretary of the German Mycological Society.

DermoTopics:
Professor Korting, why are mycoses pedis to be taken seriously and treated as early as possible?

Prof. Dr. med. Hans Christian Korting

Professor Korting:
Above all mycoses pedis are to be taken seriously because, as we know today, they are able to entail serious secondary diseases. If for example a dermatophyte infection in the interdigits, which seems to be insignificant, is not treated, it can easily spread to the entire forefoot and also seize the nail region, i. e. trigger an onychomycosis. The latter again is able to cause major complaints and consequently a considerable impairment of the quality of life. Moreover, foot mycoses are linked to a disturbance of the epidermal barrier. As a consequence, additional pathogens can penetrate skin more easily and produce independent infections. We were able to show in a case-control study in the course of a dermatological world congress in Paris last year that foot mycoses contribute to the generation of the erysipelas at the lower leg. This dermatosis is in most cases due to a streptococcus infection, which is normally linked to considerable impairment, e.g. high fever and does not seldom involve the necessity of a stationary treatment causing not least considerable costs.

DermoTopics:
Can the reason for the high incidence of mycoses pedis be attributed to insufficient therapeutical treatment methods?

Professor Korting:
Here is a differentiation necessary. Dermatophyte infections at the free part of the foot are normally treated topically and for the topical treatment there are numerous antimycotics with high efficiency available today. Problematic is however that many antimycotics have to be applied for several weeks over the stage of the subjectively perceived symptoms. This may lead to treatment failures due to non-compliance by patients. As the symptoms itching and reddening may generally ease after only few treatment days, numerous patients terminate the therapy too early. This behavior reduces the healing prospects and the risk of recurrence increases.

DermoTopics:
Your expositions concerning the necessity of a several-week therapy duration regard above all azole derivatives. For topical Terbinafine (Lamisil®) in contrast, an application duration of only seven days is claimed. Is such a short treatment time really sufficient for a safe treatment of mycoses pedis?

Widespread disease mycosis pedis: approximately one third of the population is affected by this dermatosis.

Professor Korting:
In fact topical Terbinafine has to be applied only once a day on seven days running if the toe interdigits are seized. This short-term therapy favorable for compliance has been proven for the three presentation forms terbinafine cream, dermGel and -spray available in the market in controlled clinical studies and also recognized by the authorities. Moreover, comparative clinical studies have shown that the one-week short-term therapy with Terbinafine leads to a higher or at least equally high healing rate as well as less relapse and re-infections than a four-week therapy based on the topical Clotrimazole.

DermoTopics:
Does the short-term therapy based on topical Terbinafine also have cost benefits compared with a several week therapy by means of other antimycotics?

Professor Korting:
If one considers - as is often done in superficial cost comparisons, only the prices relating to the gram of preparation of the corresponding products, then the impression is generated that in particular many azole-containing antimycotics are more cost-effective than topical Terbinafine. The price advantage of azoles is however compensated by the required high application frequency over several weeks and the relatively high product consumption caused by this fact. This is why an advantageous calculation can be made for topical Terbinafine as regards the procurement costs in spite of the still existing patent protection even compared with the, related to the unit weight, relatively low-priced azole-containing generics.

DermoTopics:
Critics maintain that the short-term therapy based on topical Terbinafine is not sufficient to regenerate the skin barrier impaired by the dermatophyte infection. Is for that reason an antimycotic therapy yet more recommendable than a short-term therapy?

Professor Korting:
The decisive fact is that the infected skin areas are clinically and mycologically healed at the termination of the therapy. If the infection and thus the cause of the barrier impairment are eliminated the epidermis swiftly regains its integrity protecting from recurrence and re-infections. An extension of the therapy beyond the stage of mycological healing has if at all an additional cosmetical benefit in the sense that the skin caring properties of the preparation base accelerates the restitution of the barrier. To date however, it has not been investigated whether or not the benefit of such a care effect is higher at a several-week therapy than at the one-week short-term therapy.

DermoTopics:
You are addressing the bases of topical antimycotics. In which way do they influence the therapy results?

Professor Korting:
As in the topical Dermatotherapy in general, the base of the product for external application used in the treatment of the mycosis pedis may influence the overall effect of the product. This for example was the result of placebo-controlled clinical studies with the Terbinafine cream available in the market. In these studies besides curing rates of 88 respectively 91 per cent for the active agent-containing cream and a relatively high mycological curing rate of 23 respectively 37 percent of the active agent-free base after only one week of application could be proven. The skin caring properties of the cream base are able to explain this surprising result. The care effect of the base is here obviously so significant that it promotes the healing of the dermatophyte infection in spite of an application of merely one week.

DermoTopics:
In which cases should a topical treatment of mycoses pedis with creams be applied and when are other presentation forms appropriate?

Professor Korting:
Due to their additionally expected care effect creams are recommended in particular with scaling forms of mycoses pedis, which are not connected with strong itching. If however, strong itching appears, the application of cooling gels is recommended. Beneficial are especially emulsion gels (for example Lamisil® DermGel®), which have both a cooling and care effect and thus combine the properties of a gel and a cream. Alcohol-containing gel bases should however, equally as alcoholic solutions only be applied in limited uses with severe skin lesions. The advantage of spray solutions is easy and comfortable application as well as the possibility to use the product without applying the fingers and also at limited bodily flexibility.

DermoTopics:
Professor Korting, thank you for the conversation (jk).

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