Xenazine

Tetrabenazine

Clinical data
Trade names	Xenazine, Nitoman
AHFS/Drugs.com	Consumer Drug Information
Pregnancy category	AU: B3 US: C (Risk not ruled out)
Routes of administration	Oral (tablets)
ATC code	N07XX06 (WHO)
Legal status
Legal status	AU: S4 (Prescription only) US: ℞-only
Pharmacokinetic data
Bioavailability	Low, extensive first pass effect
Protein binding	82–85%
Metabolism	Hepatic (CYP2D6-mediated)
Excretion	Renal (~75%) and fecal (7–16%)
Identifiers
IUPAC name (SS,RR)-3-Isobutyl-9,10-dimethoxy-1,3,4,6,7,11b-hexahydro-pyrido[2,1-a]isoquinolin-2-one
Synonyms	Ro-1-9569
CAS Number	58-46-8 Y
PubChem CID	6018
IUPHAR/BPS	4834
DrugBank	DB04844 Y
ChemSpider	5796 Y
UNII	Z9O08YRN8O
KEGG	D08575 Y
ChEMBL	CHEMBL117785 Y
ECHA InfoCard	100.000.348
Chemical and physical data
Formula	C19H27NO3
Molar mass	317.427 g/mol
3D model (JSmol)	Interactive image
Chirality	Racemic mixture
SMILES O=C3C(CC(C)C)CN2C(c1c(cc(OC)c(OC)c1)CC2)C3
InChI InChI=1S/C19H27NO3/c1-12(2)7-14-11-20-6-5-13-8-18(22-3)19(23-4)9-15(13)16(20)10-17(14)21/h8-9,12,14,16H,5-7,10-11H2,1-4H3 Y Key:MKJIEFSOBYUXJB-UHFFFAOYSA-N Y

Tetrabenazine is a drug for the symptomatic treatment of hyperkinetic movement disorders. It is marketed under the trade names Nitoman in Canada and Xenazine in New Zealand, some parts of Europe and in the United States as an orphan drug. On August 15, 2008, the U.S. Food and Drug Administration approved the use of tetrabenazine to treat chorea associated with Huntington's disease. Although other drugs had been used "off label," tetrabenazine was the first approved treatment for Huntington's disease in the U.S. The compound has been known since the 1950s.

Tetrabenazine is used as a treatment, but not as a cure, for hyperkinetic disorders such as:

The most common adverse reactions, which have occurred in at least 10% of subjects in studies and at least 5% greater than in subjects who received placebo, have been: sedation or somnolence, fatigue, insomnia, depression, suicidal thoughts, akathisia, anxiety and nausea.

There is a boxed warning associated with the use of tetrabenazine:

The precise mechanism of action of tetrabenazine is unknown. Its anti-chorea effect is believed to be due to a reversible depletion of monoamines such as dopamine, serotonin, norepinephrine, and histamine from nerve terminals. Tetrabenazine reversibly inhibits vesicular monoamine transporter 2, resulting in decreased uptake of monamines into synaptic vesicles, as well as depletion of monoamine storage.