Phenylalanine and UVA light for the treatment of vitiligo

Abstract

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.

<i>L</i>-Phenylalanine and UVA Irradiation in the Treatment of Vitiligo

“…Normal fasting L-Phe levels were similar to those re ported by Perry et al [15] and to our previous study [7], L-Phe loading resulted in high sustained plasma L-Phe lev els and a slightly elevated tyrosine level as reported earlier by us [7] and by Biella and Haustein [11], The plasma L-Phe level was higher with increased L-Phe doses. Blau et al [ 16] also observed high sustained levels of plasma L-Phe with no rise or a slight rise in plasma tyrosine levels with L-Phe loading.…”

“…Time, min The highest peak values 275.7 ± 62.7 pmol/1 with 50 mg/kg [7], 406.5±24.9 pmol/l with 70 mg/kg (n = 12) and 639.7± 29.3 pmol/1 with 100 mg/kg (n = 16) were achieved at 45 min, 1 h and 45 min, respectively. The average tyro sine level kept on increasing slightly as long as 3 h after the ingestion of ¿-Phc and was not proportional to the dose of ¿-Phe ( fig.…”

“…However, our previous (7] and other studies |9, 10,12] where no UVB irradiation was used indicate that L-Phe and UVA alone are responsible for repigmentation. Improved results have been reported when this therapy is combined with 5-MOP [17], topical L-Phe [ 12] or topical corticosteroids [18], Repigmentation during L-Phe UVA therapy is not due to increased tyrosine and dopa formation [7] but could be due to the inhibition of antibody synthesis by L-Phe or one of its metabolites and UVA. Animal experiments (19,20] support this hypothesis.…”

“…Patients with disseminated vitiligo over large parts of the body (10-40% of body area) were selected for the study, and those having vitiligo on distal extremities alone or only acrofacial vitiligo and/or with contraindication [7] were excluded. The patients who took part in the open trial were not enrolled in the blind trial.…”

Vitiligo treatment options: An evolving scenario

“…Its plasma level is found to be elevated 30-45 minutes after ingestion at the dosage of 50 mg/kg body weight (89). UVA exposure at that time or exposure to midday sun for 30 minutes may result in reasonable pigmentation after several sittings (90,91).…”