carbidopa /kär″bidō′pə/ , a dopa decarboxylase inhibitor that cannot cross the blood-brain barrier. It is administered to people with Parkinson’s disease to inhibit peripheral metabolism of levodopa. This property is significant in that it allows a greater proportion of peripheral levodopa to cross the blood-brain barrier for central nervous system effect. ▪ INDICATIONS: It is prescribed in combination with levodopa in the treatment of idiopathic Parkinson’s disease because it inhibits the degradation of levodopa in the periphery, thereby permitting a larger percentage of orally administered doses to enter the brain. ▪ CONTRAINDICATIONS: Glaucoma, hypertension, use of a monoamine oxidase inhibitor within the past 14 days, or known hypersensitivity to this drug prohibits its use. ▪ ADVERSE EFFECTS: Among the most serious adverse reactions are GI bleeding, cardiac irregularity, hemolytic anemia, tardive dyskinesia, mental depression, blurred vision, and activation of malignant melanoma.
