NCIt definition : A hydrazine derivative of dopa. Carbidopa is a peripheral dopa decarboxylase inhibitor
that is used as an adjunct to levodopa administration to prevent peripheral biosynthesis
of levodopa to dopamine, thereby reducing peripheral side effects. Carbidopa does
not penetrate the blood brain barrier so that levodopa, after it reaches the brain,
can be metabolized to dopamine by dopa decarboxylase where it exerts its effect on
dopamine receptors.;