Levodopa: uses and side effects of this drug

This drug is one of the most widely used in psychotic disorders and Parkinson's disease.

Dopamine is one of the best known neurotransmitters and one of the most important in regulating our behavior. It influences relevant aspects such as the perception of gratification and pleasure, as well as movement, memory and motivation. It is a hormone that is synthesized in different areas of the organism, one of the best known being the substantia nigra and its connection with the basal ganglia, and the neurons of the mesocortical pathway.

However, there are numerous disorders and problems that generate that it is not synthesized as much as it should, being necessary to use external mechanisms such as drugs to increase its levels. One of these drugs, frequently used, is levodopa.. In this article we will talk about it.

Levodopa: what is it?

Levodopa or L-dopa is a medication or psychopharmaceutical which has been isolated from dopa, the metabolic precursor of dopamine, which in turn is derived from tyrosine (as are all other catecholamines including noradrenaline) by the enzyme tyrosine hydroxylase.

It is a catecholamine that is part of the body, being synthesized by the body and also added externally from the diet. It is usually obtained directly from the diet. Inside the body it is degraded by the enzyme monoamine oxidase or MAOIwhich allows its synthesis and levels to be regulated.

Used externally as a medication, it allows to cope with an absence of dopamine in the brain, as it can cross the blood-brain barrier (unlike dopamine itself) and be degraded and transformed into dopamine thanks to the decarboxylase enzyme. This makes it possible to treat problems resulting from the deficit of the latter neurotransmitter, as is the case with many neurological disorders.as is the case with many motor disorders.

Mechanism of action

Levodopa works as a treatment for problems such as Parkinson's disease due to its action on the nervous system. due to its action on the nervous system. The blood-brain barrier does not allow external dopamine to penetrate the brain. However, levodopa, its immediate precursor, does have this capacity. This drug will subsequently be transformed into dopamine in the striatum of the basal ganglia through decarboxylation by dopaminergic neurons, ultimately increasing dopamine levels in the brain.

Levodopa is applied in conjunction with peripherally acting inhibitors such as carbidopacarbidopa, which allows levodopa not to be degraded in its passage through the digestive tract and to enter the central nervous system adequately.

Disorders in which it is used

Levodopa as a drug is often used in various disorders and in different situations and medical complications derived from the lack of dopamine in some brain region. Among its main medical uses are the following.

Parkinson's disease

The main and best known disorder in which Levodopa is used as a drug is Parkinson's disease. This disorder is characterized by a degeneration of the substantia nigra and the basal ganglia caused by a deficit in dopamine synthesis. The well-known Parkinsonian tremors appear, at rest, motor slowing and postural and movement problems, as well as facial inexpressiveness.

Pharmacological treatment with Levodopa is one of the most common, generating an increase in dopamine levels in the brain.. It is the drug of choice and produces a significant improvement of the symptomatology (e.g. eliminates weakness and lack of movement and in some cases reduces tremors).

Parkinson's syndromes due to encephalitis or cerebral arteriosclerosis

Inflammation of the encephalon or encephalitis can generate alterations in the cerebral nuclei that regulate dopaminergic transmission. that regulate dopaminergic transmission, movement and the nigrostriatal pathway. The use of levodopa is indicated in these cases.

Consumption of neuroleptics

One of the most common side effects of neuroleptics or antipsychotics, especially the typical or first generation ones, is the presence of extrapyramidal symptoms such as akathisia or tremors. the presence of extrapyramidal symptoms such as akathisia or tremor.. This is produced by blocking dopamine receptors in the nigrostriatal pathway (although the target of typical neuroleptics is the mesolimbic pathway, their action is non-specific and also reaches other nerve pathways).

For this reason, antiparkinsonian medication is frequently used, including levodopa (sometimes mixed with other substances such as carbidopa) in order to reduce these symptoms.

Poisoning: carbon monoxide or manganese

Another indication for levodopa is in the therapeutic use to treat nervous system damage caused by manganese or carbon monoxide poisoning. by manganese or carbon monoxide poisoning..

Side effects of levodopa

As with all psychotropic drugs, the use of levodopa can have more or less serious side effects. However, they are usually mild and in many cases temporary. The most likely side effects are typical of many other drugs: nausea, vomiting, decreased appetite, tremors and nervous twitchingThe most probable ones are typical of many other drugs: nausea, vomiting, decreased appetite, tremors and nervous contractions, blurred vision, darkening of urine, insomnia or sedation, fatigue and agitation or restlessness.

Behavioral disturbances such as hypersexuality may also appear, and paranoid-type ideations and depressive symptoms may appear. Edemas, urinary problems (excess or deficit), weakness, headaches or numbness may also appear.

In addition, more serious problems requiring immediate attention such as convulsions, persistent diarrhea, arrhythmias, suicidal ideation or allergic reactions may occur.

Contraindications and precautions

In addition to the secondary symptoms, it should be noted that it is not always advisable to use this drug. Among its many contraindications are mainly those cases in which a malignant melanoma is present (since it can activate the tumor and make it worse). Also The combined use of this drug and MAO inhibitors should also be avoided.medication against hypertension, anesthetics (can generate arrhythmia) or anticonvcolvulsants or tranquilizers (the effect is reduced).

Finally, patients with glaucoma, minors, pregnant women, subjects with psychosis (unless it is applied as an antiparkinsonian when taking neuroleptics) or cardiac problems should not consume it either, or if necessary, they should consult their doctor about the precautions to be taken.