Sapropterin dihydrochloride

Tetrahydrobiopterin

Clinical data
License data	US FDA: Kuvan
Pregnancy category	US: C (Risk not ruled out)
Routes of administration	By mouth
ATC code	A16AX07 (WHO)
Legal status
Legal status	US: ℞-only
Pharmacokinetic data
Biological half-life	4 hours (healthy adults) 6–7 hours (PKU patients)
Identifiers
IUPAC name (6R)-2-Amino-6-[(1R,2S)-1,2-dihydroxypropyl]-5,6,7,8-tetrahydropteridin-4(1H)-one
CAS Number	17528-72-2 Y
PubChem CID	44257
IUPHAR/BPS	5276
DrugBank	DB00360 Y
ChemSpider	40270 Y
ChEBI	CHEBI:59560 Y
ChEMBL	CHEMBL1201774 N
Chemical and physical data
Formula	C9H15N5O3
Molar mass	241.25 g/mol
3D model (Jmol)	Interactive image
SMILES O=C2\N=C(/NC=1NC[C@@H](NC=12)[C@@H](O)[C@@H](O)C)N
InChI InChI=1S/C9H15N5O3/c1-3(15)6(16)4-2-11-7-5(12-4)8(17)14-9(10)13-7/h3-4,6,12,15-16H,2H2,1H3,(H4,10,11,13,14,17)/t3-,4+,6-/m0/s1 Y Key:FNKQXYHWGSIFBK-RPDRRWSUSA-N Y
NY (what is this?)

Tetrahydrobiopterin (BH₄, THB), also known as sapropterin, is a naturally occurring essential cofactor of the three aromatic amino acid hydroxylase enzymes, used in the degradation of amino acid phenylalanine and in the biosynthesis of the neurotransmitters serotonin (5-hydroxytryptamine, 5-HT), melatonin, dopamine, norepinephrine (noradrenaline), epinephrine (adrenaline), and is a cofactor for the production of nitric oxide (NO) by the nitric oxide synthases. Chemically, its structure is that of a reduced pteridine derivative.

Sapropterin dihydrochloride may help lower phenylalanine levels in some people with phenylketonuria. It is FDA approved for this use along with dietary measures. Most people however, have little or no benefit.

The most common adverse effects, observed in more than 10% of patients, include headache and a running or obstructed nose. Diarrhea and vomiting are also relatively common, seen in at least 1% of patients.

No interaction studies have been conducted. Because of its mechanism, tetrahydrobiopterin might interact with dihydrofolate reductase inhibitors like methotrexate and trimethoprim, and NO-enhancing drugs like nitroglycerin, molsidomine, minoxidil, and PDE5 inhibitors. Combination of tetrahydrobiopterin with levodopa can lead to increased excitability.