Pretreatment of plantar warts with azone enhances the effect of 5-aminolevulinic acid photodynamic therapy.

5-Aminolevulinic acid (5-ALA) is a well characterized precursor in the synthesis of various endogenous porphyrins used in photodynamic therapy (PDT). It is most often administered topically into a tumor which is then irradiated with visible light at established wavelength to sensitize porphyrins accumulated therein. Our main aim in the present study was to increase the penetration of 5-ALA through the altered skin by application of 3% azone (1-dodecyl-azepan-2-one) before the application of 20% 5-ALA in patients with plantar warts: mosaic warts (MW) and myrmecia (MY). We also used 20% 5-ALA only to treat warts in other patients. We compared the therapeutic and cosmetic effects of the two treatment modalities. The lesions treated with modification of 5-ALA-PDT by pretreatment with azone responded with better effectiveness. In 18 patients subjected to 5-ALA-PDT plus 3% azone, we observed 66.7% complete response of MW and 100% of MY following PDT repeated two or three times; whereas in other 18 patients treated with 5-ALA-PDT alone, we observed only 37.5% complete response of MW and 70% of MY. These results provide evidence that the pretreatment with azone should be considered as the step that enhances 5-ALA penetration in tissues and thus increases the effectiveness of applied PDT.