Levodopa
Introduction
Levodopa, also known as L-DOPA, is a naturally occurring dietary supplement and psychoactive drug found in certain kinds of food and herbs. It is used in the clinical treatment of Parkinson's disease and Dopamine-responsive dystonia. When in the bloodstream, levodopa can cross the protective blood-brain barrier, whereas the neurotransmitter dopamine cannot. Once levodopa has entered the central nervous system (CNS), it is metabolized into dopamine by the enzyme aromatic L-amino acid decarboxylase.
History
Levodopa was first synthesized in 1911 by Casimir Funk, but it received little attention until the mid-20th century. In the 1960s, the Swedish scientist Arvid Carlsson demonstrated that levodopa could be an effective treatment for Parkinson's disease, a discovery that earned him the Nobel Prize in Physiology or Medicine in 2000.
Pharmacology
Levodopa is a prodrug of dopamine that is able to cross the blood-brain barrier. It is taken up by dopaminergic neurons and converted into dopamine. This process is mediated by the enzyme aromatic L-amino acid decarboxylase, which is abundant in the central nervous system.
Medical uses
Levodopa is used primarily to treat Parkinson's disease. This condition is characterized by the death of dopamine-producing cells in the substantia nigra part of the brain, which results in symptoms such as tremors, stiffness, and difficulty with walking and coordination. By increasing the amount of dopamine in the brain, levodopa can alleviate many of these symptoms.
Side effects
Like all medications, levodopa can cause side effects. The most common ones include nausea, vomiting, low blood pressure, and confusion. More serious side effects, such as hallucinations, psychosis, and an increased risk of skin cancer, can also occur.