Spatial distribution of 8-methoxypsoralen penetration into human skin after systemic or topical administration.

Aims: Photochemotherapy employing psoralens combined with UVA irradiation (PUVA) is a standard therapy for a variety of dermatoses. Psoralens can be administered orally or topically in the form of bath or cream preparations. Recommendations for the time of UVA irradiation are mainly based on the time course of minimal phototoxic doses.