[Problems posed by the therapeutic use of photosensitizers in dermatology]

Three phototherapeutic regimens with photosensitization are now used in dermatology: PUVA (psoralen + UVA), TUV (crude coaltar + UV), PRT (phototherapy with hematoporphyrin derivative). The efficiency of PUVA and TUV is well known in several dermatoses. PRT is now being tested experimentally. For TUV, the lack of a standardized regimen does not allow a clear-cut evaluation of the therapy. For PUVA, late side-effects, particularly carcinogenicity have to be considered. To improve efficiency and minimize the side-effects of PUVA some procedures, such as association with retinoïds, pharmaco-kinetic studies for individual adaptation of the therapeutic regimen and the use of new less mutagenic psoralens are helpful. The persistent phototoxicity following treatments with hematoporphyrin derivative constitutes the major side-effect observed, for this phototherapy.