l dopa

L-DOPA (Levodopa) is an amino acid precursor of dopamine with antiparkinsonian properties. It is a prodrug converted to dopamine by DOPA decarboxylase and can cross the blood-brain barrier. In the brain, levodopa is decarboxylated to dopamine, stimulating dopaminergic receptors and compensating for depleted endogenous dopamine in Parkinson's disease. To ensure adequate concentrations reach the central nervous system, levodopa is administered with carbidopa, a decarboxylase inhibitor that does not cross the blood-brain barrier, reducing peripheral decarboxylation and increasing CNS dopamine delivery.