Mitchell S. Wortzman

Coal tar phototherapy for psoriasis reevaluated: Erythemogenic versus suberythemogenic ultraviolet with a tar extract in oil and crude coal tar

Recent studies have questioned the therapeutic value of coal tar versus ultraviolet (UV) radiation and their relative necessity in phototherapy for psoriasis. In this investigation, different aspects of tar phototherapy have been studied in single-blind bilateral paired comparison studies. The effects of 1% crude coal tar were compared with those of petrolatum in conjunction with erythemogenic and suberythemogenic doses of ultraviolet light (UVB) using a FS72 sunlamp tubed cabinet. Crude coal tar was clinically superior to petrolatum with suberythemogenic ultraviolet. With the erythemogenic UVB, petrolatum was equal in efficacy to crude coal tar. Suberythemogenic UVB was also used adjunctively to compare the effects of a 5% concentration of a tar extract in an oil base to 5% crude coal tar in petrolatum or the oil base without tar. The tar extract in oil plus suberythemogenic UVB produced significantly more rapid improvement than the oil base plus UVB. The direct bilateral comparison of equal concentrations of tar extract in oil base versus crude coal tar in petrolatum in a suberythemogenic UV photo regimen revealed no statistical differences between treatments. In a study comparing tar extract in oil and the oil base without ultraviolet radiation, the tar extract in oil side responded more rapidly. This demonstrates a direct effect of tar alone in therapy. We have also studied the effects of erythemogenic and suberythemogenic UVB with and without tar extract in oil in the hairless mouse epidermal deoxyribonucleic acid (DNA) synthesis suppression assay. It was found that erythemogenic dosages of UVB produced near maximal inhibition of DNA synthesis with or without coal tars. Suberythemogenic dosages of UVB produced submaximal suppression of DNA synthesis that was enhanced by adjunctive coal tar but not by vehicle, findings which are consistent with the above clinical results. These studies suggest that coal tars combined with suberythemogenic UVB therapy is a practical alternative (to more aggressive UVB therapy without coal tar) which reduces the UVB exposure to the patient.

The pharmacological variability of crude coal tar

Although crude coal tar is a mixture of approximately 10,000 components, few attempts have been made to assess the pharmacological activity of individual components of purified tar products or of different coal tars themselves. The hairless mouse epidermal DNA synthesis suppression assay, which has been shown to be useful for predicting the antiproliferative activity of topical agents, has recently been used to assess the activity of crude coal tar, coal tar extracts and tar based shampoos. Using this assay, great variation in effectiveness (0–90%) was found among tar distillate fractions, suggesting that one source of potential variation of activity in commercial coal tar products is the non‐standard composition of crude coal tar itself.

Ciclopirox gel for seborrheic dermatitis of the scalp

Background  Seborrheic dermatitis is a common inflammatory skin disorder that usually occurs in patients with pre‐existing seborrhea. The etiology of seborrheic dermatitis is uncertain. Typically, sites dense with sebaceous glands support growth of the lipophilic yeast Malassezia furfur. Ciclopirox (Loprox®) gel is a hydroxypyridone, broad‐spectrum antifungal agent proven effective against the yeast M. furfur.

Ciclopirox gel in the treatment of patients with interdigital tinea pedis

Background  Tinea pedis (athlete’s foot) is the most common fungal infection in the general population. Ciclopirox, a broad‐spectrum hydroxypyridone antifungal, has proven efficacy against the organisms commonly implicated in tinea pedis: Trichophyton rubrum, T. mentagrophytes and Epidermophyton floccosum.

Animal assays for anti‐psoriatic., retinoid and sunprotective agents

It is possible to evaluate different dermatological therapeutic agents intended for human use in a variety of animal assays. This review will discuss some of these assays, and attempt to correlate animal and human skin responses.