The FDA has approved Novo Nordisk’s Tretten, indicated to treat a rare clotting disorder known as congenital Factor XIII A-subunit deficiency, the agency said Dec. 23. The approval of Tretten, a recombinant analogue of the human Factor XIII A-subunit, is based on a Phase III study of 77 patients with the clotting deficiency, which showed statistically significant decreases in bleeding episodes requiring treatment, according to the FDA.

Tretten is a sterile, freeze-dried powder made into a liquid with a diluting agent and then injected. It replaces the A subunit of Factor XIII, a protein in the blood that aids in clotting. Factor XIII has two subunits: A and B; the rare deficiency is usually caused by the A subunit.

This rare condition affects one in 3 to 5 million births in the U.S., Novo Nordisk says.

Novo Nordisk expects the orphan drug to be available in the U.S. in early 2014. It is marketed in Canada as Tretten and in the EU, Switzerland and Australia as NovoThirteen. — Lena Freund