Topical ALA-photodynamic therapy for the treatment of acne vulgaris

Topical aminolevulinic acid is converted into a potent photosensitizer, pro toporphyrin, in human hair follicles and sebaceous glands. Photodynamic the rapy with topical aminolevulinic acid was tested for the treatment of acne vulgaris, in an open-label prospective human study. Each of 22 subjects wit h acne on the back was treated in four sites with aminolevulinic acid plus red light, aminolevulinic acid alone, light alone, and untreated control. H alf of the subjects were treated once; half were treated four times. Twenty percent topical aminolevulinic acid was applied with 3 h occlusion, and 15 0 J per cm(2) broad-band light (550-700 nm) was given. Sebum excretion rate and auto-fluorescence from follicular bacteria were measured before, and 2 , 3, 10, and 20 wk after, treatment. Histologic changes and protoporphyrin synthesis in pilosebaceous units were observed from skin biopsies. Aminolev ulinic acid plus red light caused a transient acne-like folliculitis. Sebum excretion was eliminated for several weeks, and decreased for 20 wk after photodynamic therapy; multiple treatments caused greater suppression of seb um. Bacterial porphyrin fluorescence was also suppressed by photodynamic th erapy. On histology, sebaceous glands showed acute damage and were smaller 20 wk after photodynamic therapy. There was clinical and statistically sign ificant clearance of inflammatory acne by aminolevulinic acid plus red ligh t, for at least 20 wk after multiple treatments and 10 wk after a single tr eatment. Transient hyperpigmentation, superficial exfoliation, and crusting were observed, which cleared without scarring. Topical aminolevulinic acid plus red light is an effective treatment of acne vulgaris, associated with significant side-effects. Aminolevulinic acid plus red light causes photot oxicity to sebaceous follicles, prolonged suppression of sebaceous gland fu nction, and apparent decrease in follicular bacteria after photodynamic the rapy. Potentially, aminolevulinic acid plus red light may be useful for som e patients with acne.