Asubio’s Biopten is said to be a highly pure chemically synthesized form of the tetrahydrobiopterin (BH4) that occurs naturally in the human body. It treats hyperphenylalaninemia (HPA) patients by ameliorating the serum phenylalanine level.
Maruho marketed Biopten under a contract that expired at the end of June, 2008. From July 1, 2008 Daiichi Sankyo began marketing Biopten under a contract.