Nitisinone

Nitisinone is an orally active, competitive and reversible 4-hydroxyphenylpyruvate dioxygenase (4-HPPD) inhibitor with an IC₅₀ of 173 nM. Nitisinone promotes tyrosine accumulation in a dose-dependent manner. nitisinone can be used in studies of hereditary tyrosinemia type 1 (HT-1) (a rare genetic disorder) and albinism^[1][2][3][4]. In Vitro: Nitisinone (0.01-10 µM; 72 h) promotes tyrosine accumulation in a dose-dependent manner^[1]. In Vivo: Nitisinone (5, 10 mg/kg; p.o.; 5 days aweek for 6 weeks) inhibits HPPD in a dose- and time- dependent manner in rat liver^[2].
Nitisinone (4 mg/kg; p.o.; single daily; one day interval for 1 month) elevates tyrosine in both OCA-1A and OCA-1B model^[3].
Nitisinone (4 mg/kg; p.o.; single daily; one day interval for 1 month) increases coat and iris pigmentation and melanin content in the melanosomes of ocular tissues in a mouse model of OCA-1B^[3].
Note: Oculocutaneous albinism, type 1 (OCA1). There are 2 forms of OCA1, OCA-1A and OCA-1B. Individuals with the former lack functional tyrosinase and therefore lack melanin, while individuals with the latter produce some melanin^[3].