Carbidopa

Carbidopa
Systematic (IUPAC) name
(2S)-3-(3,4-dihydroxyphenyl)-2-hydrazinyl-2-methyl- propanoic acid
Identifiers
CAS number	38821-49-7
ATC code	?
PubChem	34359
DrugBank	APRD00160
Chemical data
Formula	C10H14N2O4
Mol. mass	226.229 g/mol
Pharmacokinetic data
Bioavailability	?
Protein binding	76%
Metabolism	decarboxylated to dopamine in extracerebral tissues
Half life	2 hours
Excretion	?
Therapeutic considerations
Licence data	US
Pregnancy cat.	?
Legal status	POM(UK)
Routes	?

Carbidopa (MK-486) is a drug given to people with Parkinson's disease in order to inhibit peripheral metabolism of levodopa.

Carbidopa inhibits aromatic-L-amino-acid decarboxylase (DOPA Decarboxylase or DDC), an enzyme important in the biosynthesis of L-tryptophan to serotonin and in the biosynthesis of L-DOPA to Dopamine (DA). Along with carbidopa, other DDC inhibitors are benserazide (Ro-4-4602), difluromethyldopa, and α-methyldopa.

Used in tandem with L-DOPA (trade name levodopa, a dopamine precursor converted in the body to dopamine), it increases the plasma half-life of levodopa from 50 minutes to 1 1/2 hours. CarbiDOPA cannot cross the blood brain barrier, so it inhibits only peripheral DDC. It thus prevents the conversion of L-DOPA to dopamine peripherally. This reduces the side effects caused by dopamine on the periphery, as well as increasing the concentration of L-DOPA and dopamine in the brain.

The combination of L-DOPA and carbiDOPA carries the brand names of Sinemet®, Parcopa® and Atamet®.

Carbidopa is also used in combination with 5-HTP, a naturally-occurring amino acid which is a precursor to the neurotransmitter serotonin and an intermediate in tryptophan metabolism. Carbidopa prevents 5-HTP's metabolism in the liver, which can lead to elevated levels of serotonin in the bloodstream. Research shows that co-administration of 5-HTP and carbidopa greatly increases plasma 5-HTP levels.

External links

• Sinemet® datasheet

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