Nitisinone, sold under the brand name Nityr and Orfadin among others, is a medication used to slow the effects of hereditary tyrosinemia type 1 (HT-1). Uses
Nitisinone is used to treat hereditary tyrosinemia type 1 (HT-1) in patients from all ages, in combination with dietary restriction of tyrosine and phenylalanine.Since its first use for this indication in 1991, it has replaced liver transplantation as the first-line treatment for this ultra rare condition. Adverse effects
The most common adverse reactions (>1%)  for nitisinone are elevated tyrosine levels, thrombocytopenia, leukopenia, conjunctivitis, corneal opacity, keratitis, photophobia, eye pain, blepharitis, cataracts, granulocytopenia, epistaxis, pruritus, exfoliative dermatitis, dry skin, maculopapular rash and alopecia.has several negative side effects; these include but are not limited to: bloated abdomen, dark urine, abdominal pain, feeling of tiredness or weakness, headache, light-colored stools, loss of appetite, weight loss, vomiting, and yellow-colored eyes or skin. Mechanism of action
The mechanism of action of nitisinone involves inhibition of 4-Hydroxyphenylpyruvate dioxygenase (HPPD). This is a treatment for patients with Tyrosinemia type 1 as it prevents the formation of 4-Maleylacetoacetic acid and fumarylacetoacetic acid, which have the potential to be converted to succinyl acetone, a toxin that damages the liver and kidneys. This causes the symptoms of Tyrosinemia type 1 experienced by untreated patients.Alkaptonuria is caused when an enzyme called homogentisic dioxygenase (HGD) is faulty, leading to a buildup of homogenisate. Alkaptonuria patients treated with nitisinone produce far less HGA than those not treated (95% less in the urine),  because nitisinone inhibits HPPD, resulting in less homogenisate accumulation.
Where relapse occurs, conventional treatment should be resumed, including hydralazine with nitrates plus beta-blockers during pregnancy, or ACE-inhibitors plus beta-blockers following pregnancy. Epidemiology
It is estimated that the incidence of PPCM in the United States is between 1 in 1300 to 4000 live births. While it can affect women of all races, it is more prevalent in some countries; for example, estimates suggest that PPCM occurs at rates of one in 1000 live births in South African Bantus, and as high as one in 300 in Haiti.Some studies assert that PPCM may be slightly more prevalent among  older women who have had higher numbers of liveborn children and among women of older and younger extremes of childbearing age. However, a quarter to a third of PPCM patients are young women who have given birth for the first time.While the use of tocolytic agents or the development of preeclampsia (toxemia of pregnancy) and pregnancy-induced hypertension (PIH) may contribute to the worsening of heart failure, they do not cause PPCM; the majority of women have developed PPCM who neither received tocolytics nor had preeclampsia nor PIH.In short, PPCM can occur in any woman of any racial background, at any age during reproductive years, and in any pregnancy. References


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