Carbidopa

drugbox
IUPAC_name = (2"S")-3-(3,4-dihydroxyphenyl)-2-hydrazinyl-2-methyl-
propanoic acid

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CAS_number = 28860-95-9
ATC_prefix =
ATC_suffix =
ATC_supplemental =
PubChem = 34359
DrugBank = APRD00160
C=10 | H=14 | N=2 | O=4
molecular_weight = 226.229 g/mol
bioavailability =
protein_bound = 76%
metabolism = decarboxylated to dopamine in extracerebral tissues
elimination_half-life = 2 hours
excretion =
licence_EU =
licence_US = Carbidopa
pregnancy_AU =
pregnancy_US =
pregnancy_category =
legal_AU =
legal_UK = POM
legal_US =
legal_status =
routes_of_administration =

Carbidopa (MK-486, tradename Lodosyn) 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 carbidopa/levodopa) carries the brand names of Sinemet, Parcopa and Atamet; whilst Stalevo is a combination with entacapone, which enhances the bioavailability of carbidopa and levodopa.

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

* [http://packageinserts.bms.com/pi/pi_lodosyn.pdf Lodosyn prescribing information]
* [http://www.medsafe.govt.nz/profs/Datasheet/s/Sinemettab.htm Sinemet datasheet for New Zealand]