Description of the medicine: Levodopa (Levodopum)
LEVODOPA (Levodopum). (-) - 3- (3, 4-dioxiphenyl) -1-alanine, or 3-hydroxy-1-tyrosine.
Synonyms: Kaldopa, Levopa, Avodopa, Bendopa, Biodopa, Brocadopa, Caldopa, Cicandopa, Dalutrin, Deadopa, Dopacin, Dopaflex, Dopal, Dopar, Doparkin, Dopastral, Doprin, Eldopar, Eurodopa, Lopod, Laropop, Laropop, Laropop, Laropop, Laropop, Laropop, Laropop, Laropop, Laropop, Laropop, Laropop Medidopa, Oridopa, Pardopa, Parkidopa, Parmidin, Speciadopa, Tonodopa, Veldopa, etc.
White crystalline powder, slightly soluble in water, insoluble in alcohol.
Dioxyphenylalanine (abbreviated dopa, or dopa) is a biogenic substance that is formed in the body from tyrosine and is a precursor of dopamine, which in turn is a precursor of norepinephrine (see Adrenaline).
Due to the fact that with parkinsonism, the dopamine content in the basal ganglia of the brain is lowered, it is advisable to use substances that increase the content of this amine in the central nervous system to treat this disease. Dopamine itself cannot be used for this purpose, since it penetrates poorly through the blood-brain barrier. It turned out that instead of dopamine, its precursor, dioxiphenylalanine (dopa), which is absorbed by oral administration, penetrates into the central nervous system, undergoes decarboxylation, turns into dopamine and, replenishing its reserves in the basal ganglia, stimulates dopamine receptors and provides a therapeutic effect for parkinsonism .
As a medicine, a synthetic levorotatory isomer of dioxiphenylalanine - L-dopa, which is much more active than the dextrorotatory isomer, is used.
Levodopa is well absorbed when taken orally. The maximum plasma concentration is observed 1 to 2 hours after administration. It is secreted to a significant extent (over 75%) by the kidneys, partly with feces.
Most of the levodopa is converted by decarboxylation in the tissues (liver, kidneys, intestines) into dopamine, which does not cross the blood-brain barrier. To reduce decarboxylation, levodopa is used with dopa-decarboxylase inhibitors (see Nakom, Madopar).
The use of L-dopa in parkinsonism primarily reduces hypokinesia and rigidity, tremor, dysphagia, and salivation decrease to a lesser and later extent. It was found that the therapeutic effect is achieved in 50-60% of patients. In others, the effect is not very pronounced, the dose of the drug cannot be increased due to side effects.
The drug is prescribed for Parkinson's disease and symptomatic (postencephalitic, atherosclerotic, toxic) parkinsonism. There are indications of the effectiveness of the drug in hereditary extrapyramidal diseases characterized by akinetorigid syndrome. The effectiveness of L-DOPA in the treatment of deforming muscular dystonia was also found. There is evidence of the treatment of L-DOPA in reactive stuporous conditions (especially in patients with reduced dopamine excretion).
As a corrector for the phenomena of parkinsonism caused by antipsychotics, L-DOPA is not prescribed.