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The administration of phenylalanine (Phe) combined with UVA exposure was found to be effective in vitiligo. Phe is an amino acid which constitutes part of the daily dietary protein, and when orally administered in a dose of 50 mg/kg body weight, it results in an elevated plasma level. Since peak concentrations of Phe in the blood are reached between 30 and 45 min after ingestion, UVA exposure was administered at this time. After 4 months (32 treatments) reasonable repigmentation preferentially occurred in the skin area of subcutaneous fat (adipose tissue). Apart from the repigmentation of hypo-pigmented macules, vitiligo patients can tolerate more sun than usual, especially at the vitiliginous lesion, and they experience no sunburn as a result of Phe-UVA therapy. Normal skin also tans very well.

In order to evaluate the efficacy of L-phenylalanine (L-Phe) in combination with UVA therapy for vitiligo an open trial (149 patients, 18 months) and a small double-blind trial (32 patients, 6 months) were conducted. Oral L-Phe loading resulted in peak plasma levels of L-Phe after 30–60 min and a slight increase in the plasma tyrosine level. Response to L-Phe plus UVA irradiation was positive, and various grades of repigmentation not exceeding 77% in the open and 60% in the blind trial were observed. An increased L-Phe dose resulted in increased L-Phe plasma levels but not in improved clinical results. The optimal L-Phe dose appears to be lower than 50 mg/kg/day. Although it is difficult to draw firm conclusions from the present investigation, we think that L-Phe may have a place in the treatment of vitiligo and its role merits further investigation.

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No abstract