L-3,4-L-Dihydroxyphenylalanine / 3,4-Dihydroxy-L-Phenylalanine
White or almost white, crystalline powder
Slightly soluble in water, practically insoluble in ethanol(96%). It is freely soluble in 1M hydrochloric acid and sparingly soluble in 0.1M hydrochloric acid.
Degeneration of the substantia nigra occurs in patients with Parkinson's disease. This condition results in the disruption of the nigrostriatal pathway and thus, decreasing the striatal dopamine levels. Unlike dopamine, levodopa can cross the blood-brain barrier (BBB). Levodopa converts to dopamine in both the CNS and periphery. To increase the bioavailability of levodopa and decrease its side effects, it is often administered in combination with peripheral decarboxylase inhibitors (such as carbidopa and benserazide). Dopamine decarboxylase inhibitors prevent the conversion of levodopa to dopamine in the periphery, allowing for more levodopa to cross the BBB. Once converted to dopamine, it activates postsynaptic dopaminergic receptors and compensates for the decrease in endogenous dopamine.
【Function and application】
Levodopa is the precursor to dopamine. Most commonly, clinicians use levodopa as a dopamine replacement agent for the treatment of Parkinson's disease. It is most effectively used to control bradykinetic symptoms that are apparent in Parkinson's disease, and it is the most effective medication to improve the quality of life in patients with idiopathic PD. The drug is also useful for post-encephalitic parkinsonism and symptomatic parkinsonism due to carbon monoxide intoxication.