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Carbidopa
- indication:For treatment of the symptoms of idiopathic Parkinson's disease (paralysis agitans), post-encephalitic parkinsonism
- pharmacologypharmacology:
- mechanism: When mixed with levodopa, carbidopa inhibits the peripheral conversion of levodopa to dopamine and the decarboxylation of oxitriptan to serotonin by aromatic L-amino acid decarboxylase. This results in increased amount of levodopa and oxitriptan available for transport to the CNS. Carbidopa also inhibits the metabolism of levodopa in the GI tract, thus, increasing the bioavailability of levodopa.
- toxicity: Symptoms of a carbidopa toxicity include muscle spasms or weakness, spasms of the eyelid, nausea, vomiting, diarrhea, an irregular heartbeat, confusion, agitation, hallucinations, and unconsciousness.
- absorprion: Rapidly decarboxylated to dopamine in extracerebral tissues so that only a small portion of a given dose is transported unchanged to the central nervous system.
- halflife: 1-2 hours
- roouteelimination: In clinical pharmacologic studies, simultaneous administration of separate tablets of carbidopa and levodopa produced greater urinary excretion of levodopa in proportion to the excretion of dopamine when compared to the two drugs administered at separate times.
- volumedistribution:
- clearance: