Phenylalanine Chemical formula
Synonyms: laninas; Fenylalanin; Fenyloalanina; Fenyylialaniini; Phe; Phénylalanine; pionic acid.
Cyrillic synonym: Фенилаланин.

💊 Chemical information

Chemical formula: C9H11NO2 = 165.2.
CAS — 63-91-2.


In Chin., Eur., Jpn, and US.

Ph. Eur. 6.2

(Phenylalanine). A white or almost white, crystalline powder, or shiny, white flakes. Sparingly soluble in water; very slightly soluble in alcohol. It dissolves in dilute mineral acids and in dilute solutions of alkali hydroxides. Protect from light.

USP 31

(Phenylalanine). White, odourless crystals. Sparingly soluble in water; very slightly soluble in alcohol, in methyl alcohol, and in dilute mineral acids. pH of a 1% solution in water is between 5.4 and 6.0.

💊 Profile

Phenylalanine is an aromatic amino acid that is an essential constituent of the diet. It is used as a dietary supplement. Phenylalanine intake should be restricted in patients with phenylketonuria.


There is no totally effective treatment for vitiligo. Oral or topical photochemotherapy with psoralens is generally considered to be the best available treatment, but experimental therapy includes UVA phototherapy with phenylalanine. Use of phenylalanine in oral doses of up to 100 mg/kg with UVA/sunlight led to beneficial results in more than 90% of 200 patients with vitiligo.1 Greatest benefit was noted in early disease, but prolonged use still induced repigmentation in long-standing cases. Repigmentation occurred mainly in areas rich in follicles. Such therapy is contraindicated in phenylketonuria and in pregnancy. Similarly a further open study reported responses in 94 of 149 patients receiving 50 to 100 mg/kg daily of phenylalanine plus twice weekly UVA treatment.2 However, only 22% of responders had repigmentation in more than 60% of the affected area. Higher doses did not seem to be more effective than 50 mg/kg daily. Another group reported on 6 years of experience of treatment of vitiligo using 50 or 100 mg/kg daily of phenylalanine, with application of 10% phenylalanine gel and daily sun exposure.3 Although not ideal, they considered the treatment useful, especially for its ability to rapidly repigment the face. The same group performed an open study, adding topical 0.025% clobetasol propionate, and ultraviolet exposure during autumn and winter; 65.5% of patients achieved 100% repigmentation on the face.4
1. Cormane RH, et al. Treatment of vitiligo with -phenylalanine and light. Br J Dermatol 1986; 115: 587
2. Siddiqui AH, et al. L-Phenylalanine and UVA irradiation in the treatment of vitiligo. Dermatology 1994; 188: 215–18
3. Camacho F, Mazuecos J. Treatment of vitiligo with oral and topical phenylalanine: 6 years of experience. Arch Dermatol 1999; 135: 216–17
4. Camacho F, Mazuecos J. Oral and topical L-phenylalanine, clobetasol propionate, and UVA/sunlight - a new study for the treatment of vitiligo. J Drugs Dermatol 2002; 2: 127–31.

💊 Preparations

Proprietary Preparations

Multi-ingredient: Arg.: KLB6 Fruit Diet; Fr.: Revitalose.
Published January 21, 2019.