Information about Nitisinone
Nitisinone is an inhibitor of the tyrosine catabolism that is used to treat hereditary tyrosinemia, type 1, in which accumulation of intermediates of tyrosine metabolism causes severe and progressive hepatic and renal injury.
Liver safety of Nitisinone
Nitisinone has been associated with mild, transient serum aminotransferase elevations, but has not been linked to instances of clinically apparent acute liver injury or jaundice.
Mechanism of action of Nitisinone
Nitisinone (nye tis’ i none) is a small molecule inhibitor of 4-hydroxyphenylpyruvate the second enzymatic step in tyrosine metabolism. Developed initially as an herbicide, it was later found to be beneficial in hereditary type 1 tyrosinemia in which the absence of fumarylacetoacetate hydrolase (FAH), the fifth step in tyrosine catabolism, causes buildup of toxic intermediates that cause early onset liver failure and severe renal tubular dysfunction. Treatment of infants and children with nitisinone combined with a low protein diet led to reversal of liver failure and correction of renal tubular dysfunction, allowing for normal growth and development. Children treated before the onset of liver failure avoided the need for liver transplantation and did not develop hepatocellular carcinoma, common outcomes before the availability of this agent.
FDA approval information for Nitisinone
Nitisinone was approved as an orphan drug for use in tyrosinemia, type 1, in the United States in 2002.
Dosage and administration for Nitisinone
Nitisinone is available in tablets of 2, 5, 10 and 20 mg and as an oral suspension of 4 mg/mL under the brand name Orfadin. The recommended dose is 0.5 mg/kg orally given twice daily, but monitoring with drug and tyrosine levels is usually recommended and can lead to dose modification.
Side effects of Nitisinone
Side effects are infrequent, but serious complications include corneal irritation, opacities and ulcers, skin rash, developmental delay and intellectual disability, leukopenia and thrombocytopenia. Most of these serious side effects of nitisinone are thought to be due to the elevation in plasma tyrosine levels which typically increase ten-fold during treatment. These increases can be partially prevented by limiting tyrosine and phenylalanine intake by a low or limited protein diet, a necessary component in the therapy of this disease.
genetic disorder agents
- gaucher disease agents
glucosylceramide synthase inhibitors (substrate restriction therapy)
lysosomal acid lipase deficiency agents
- agalsidase beta, alglucosidase alfa, alpha1-proteinase inhibitor, elosulfase alfa, galsulfase, idursulfase, laronidase, pegademase
Huntington disease agents
Urea Cycle Disorder Agents