A new psoralen-containing gel for topical PUVA therapy: development, and treatment results in patients with palmoplantar and plaque-type psoriasis, and hyperkeratotic eczema

Summary Topical photochemotherapy with psoralen and its derivatives 4.5′,8‐trimethylpsoralen (TMP) and 8‐methoxypsoralen (8‐MOP), with UVA irradiation, was evaluated with regard to minimum phototoxic dose, concentration, timing of UVA irradiation and systemic and local side‐effects, in healthy volunteers. Psoralen (0.005%) in aqueous gel was found to be superior to TMP and 8‐MOP in aqueous gel. No hyperpigmentation was seen after topical PUVA treatment with psoralen in aqueous gel. Patients with plaque‐type psoriasis (n = 7), palmoplantar psoriasis (n = 7) and hyperkeratotic eczema (n = 2) were treated. Topical PUVA therapy was effective in most psoriasis patients, without the occurrence of local or systemic side‐effects. Moreover, hyperkeratotic eczema patients who did not respond to conventional therapy showed partial remission. These results indicate that topical PUVA therapy with psoralen in aqueous gel is a useful therapeutic modality for treatment of psoriasis patients, and patients with recalcitrant dermatoses such as palmoplantar psoriasis and hyperkeratotic eczema.