Merck KGaA says that regulators in Europe have given the go-ahead for the firm to start selling Kuvan which treats a rare brain disorder.

The German company’s Merck Serono unit has received marketing authorisation from the European Commission for Kuvan (sapropterin) as an oral treatment for hyperphenylalaninemia (HPA) caused by phenylketonuria (PKU) or tetrahydrobiopterin (BH4) deficiency. The drug was developed in tandem with BioMarin Pharmaceutical.

Merck notes that there are 35,000 patients diagnosed with HPA due to PKU or BH4 deficiency in the European Union, adding that the only therapy option for patients to manage their disease was through a diet highly restricted in phenylalanine associated with daily amino-acid supplementation. Non-adherence to the aforementioned diet and adequate control of blood phenylalanine levels “can result in a decline in mental and behavioral performance”, the firm added.

The approval covers the 27 countries of the EU, as well as Iceland, Liechtenstein and Norway, and as an orphan drug, Kuvan will receive 10 years of marketing exclusivity. Launches in Europe are expected to start in the first half of 2009.

Kuvan received approval from the US Food and Drug Administration a year ago, where it is marketed by BioMarin. In July this year, Asubio Pharma Co, a subsidiary of Daiichi Sankyo, received marketing approval from the Japanese Ministry of Health, Labour and Welfare for a label extension of Biopten, which contains the same active ingredient as Kuvan, for the treatment of patients with PKU.