The Food and Drug Administration (FDA) has approved Nityr (nitisinone tablets) for the treatment of hereditary tyorsinemia type 1 (HT-1) in combination with dietary restriction of tyrosine and phenylalanine.

Nityr is the first formulation of nitisinone that does not require refrigeration; it is clinically proven to be bioequivalent to current nitisinone capsules. In addition, the tablets are small (20% of the volume of capsules) which may ease swallowing difficulties. They can also be disintegrated in water and administered via oral syringe.

The safety and efficacy of Nityr have been established based on studies of another oral formulation of nitisinone in patients with HT-1.

Nitisinone is a competitive inhibitor of 4-hydroxyphenyl-pyruvate dioxygenase, an enzyme upstream of fumarylacetoacetate hydrolase (FAH) in the tyrosine catabolic pathway. By inhibiting the normal catabolism of tyrosine in patients with HT-1, nitisinone prevents the accumulation of the catabolic intermediates maleylacetoacetate and fumarylacetoacetate. In patients with HT-1, these catabolic intermediates are converted to the toxic metabolites succinylacetone and succinylacetoacetate, which are responsible for the observed liver and kidney toxicity.

Nityr treatment requires restriction of the dietary intake of tyrosine and phenylalanine to prevent the toxicity associated with elevated plasma levels of tyrosine.

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Speaking about the approval, Jon Miller, President of the Network of Tyrosinemia Advocates said, “Since this new treatment is a small tablet and does not need refrigeration, it may offer convenience and a better quality of life to patients and families who struggle with the debilitating effects of HT-1.”

Nityr will be available in 2mg, 5mg and 10mg strength tablets.

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