Levodopa: uses and side effects of this drug

Dopamine is one of the best-known neurotransmitters and one of the most important when it comes to regulating our behavior. It influences such relevant aspects 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 body, 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 cause it not to be synthesized as much as it should, making it 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 him.

• Related article: "Types of psychoactive drugs: uses and side effects"

Levodopa: what is it?

Levodopa or L-dopa is a medication or psychoactive drug that has been isolated from dopa, the metabolic precursor of dopamine, which in turn is derived from tyrosine (like the rest of catecholamines including norepinephrine) thanks to the enzyme tyrosine hydroxylase.

It is a catecholamine that is part of the organism, being synthesized by it at the same time that it is also added externally from the diet. it is usually obtained directly from the diet. inside the body is broken down by the enzyme monoamine oxidase or MAOI, which allows to regulate its synthesis and levels.

Used externally as a medication, it makes it possible to deal with a lack of dopamine in the brain, by being able to cross the blood-brain barrier (unlike dopamine itself) and be degraded and transformed into dopamine thanks to the enzyme decarboxylase. This makes it possible to treat problems derived from the deficit of this last neurotransmitter., as occurs with many alterations of a motor nature.

Mechanism of action

Levodopa works as a treatment for problems such as Parkinson's due to its action on the nervous system. The blood-brain barrier does not allow external dopamine to enter the brain. However levodopa, its immediate precursor, does have this ability. This drug will later be transformed into dopamine in the striatum of the basal ganglia thanks to the decarboxylation produced by dopaminergic neurons, which will eventually end up increasing dopamine levels in the brain

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

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, the following stand out.

Parkinson's

The main and best known disorder in which levodopa is used as a medication is in the Parkinson's disease. This disorder is characterized by a degeneration of the substantia nigra and in the basal ganglia produced by a deficit in the synthesis of dopamine. The well-known parkinsonian tremors appear, at rest, motor slowdown and postural and movement problems, as well as facial expressionlessness.

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 in symptoms (for example, it eliminates weakness and lack of movement and in some cases reduces tremors).

Parkinsonian syndromes due to encephalitis or derived from cerebral arteriosclerosis

Inflammation of the brain or encephalitis can cause alterations in the brain nuclei 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. This is produced by the blockade of dopamine receptors in the nigrostriatal pathway (although the objective of the dopamine receptors is typical neuroleptics is the mesolimbic pathway, its action is non-specific and also reaches other pathways nervous).

For this reason, the use of antiparkinsonian medication is frequent, using among other substances the levodopa (sometimes mixed with other substances such as carbidopa) in order to reduce such symptoms.

• You may be interested in: "Extrapyramidal symptoms: types, causes and treatment"

Poisoning: carbon monoxide or manganese

Another of the indications for levodopa is in its therapeutic use in order to treat damage to the nervous system caused by from manganese or carbon monoxide poisoning.

side effects of levodopa

As with all psychoactive drugs, the consumption of levodopa can have more or less serious side effects. However, in general we are dealing with mild discomfort and in many temporary cases. The most likely are typical of many other drugs: nausea, vomiting, decreased appetite, tremors, and nervous twitching, blurred vision, dark urine, insomnia or sedation, fatigue, and agitation or restlessness.

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

In addition to this, it must be taken into account that there may be more serious problems that require attention. such as seizures, persistent diarrhoea, arrhythmias, suicidal ideation or reactions allergic.

Contraindications and precautions

In addition to the secondary symptoms, it must be taken into account that it is not always going to be advisable to use this drug. Among its multiple contraindications are mainly those cases in which a malignant melanoma is suffered (since it can activate the tumor and make it worse). Also joint consumption of this medication and MAO inhibitors should be avoided, medication against hypertension, anesthetics (can generate arrhythmia) or anticonvulsants or tranquilizers (the effect is reduced).

Finally, patients with glaucoma, minors, pregnant women, subjects with psychosis (unless it is applied as an antiparkinsonian before consumption). neuroleptics) or heart problems should not consume it or if necessary they should consult with their doctor what precautions use.