Levodopa: uses and side effects of this drug
Dopamine is one of the best known neurotransmitters and one of the most important in regulating our behavior. It influences aspects as important 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, being necessary to use external mechanisms such as drugs to increase their levels. One of these drugs, often used, is levodopa . In this article we will talk about him.
- Related article: "Types of psychotropic drugs: uses and side effects"
Levodopa: what is it?
Levodopa or L-dopa is a medication or psychopharmaceutical that has been isolated from dopa, the metabolic precursor of dopamine, which in turn is derived from tyrosine (like the rest of catecholamines including noradrenaline) thanks to the enzyme tyrosine hydroxylase.
It is a catecholamine that is part of the body, being synthesized by it while also being added externally from the diet. It is usually achieved directly from the diet. Inside the body is degraded by the enzyme monoamine oxidase or MAOI , which allows to regulate its synthesis and levels.
Used externally as a medication, it allows us to deal with an absence of dopamine at the cerebral level, by being able to cross the blood-brain barrier (as opposed to dopamine itself) and to degrade and transform into dopamine thanks to the enzyme decarboxylase. This allows to treat problems derived from the deficit of this last neurotransmitter , as it happens with many alterations of motor character.
Mechanism of action
Levodopa works as a treatment for problems such as Parkinson's due to its performance 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 capacity. This drug will later be transformed into dopamine in the striatum of the basal ganglia thanks to the decarboxylation produced by the dopaminergic neurons, with which finally it will end up increasing the levels of dopamine in the encephalon.
The levodopa is applied in conjunction with inhibitors of peripheral action such as carbidopa , which allows that levodopa does not degrade 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 include the following.
Parkinson
The main and most known disorder in which Levodopa is used as a medication is in 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 known parkinsonian tremors appear, in rest situation, motor slowness and postural and movement problems, as well as facial inexpressiveness.
The pharmacological treatment with Levodopa is one of the most common, generating an increase in brain dopamine levels . It is the drug of choice and produces a significant improvement in symptoms (for example, eliminates weakness and lack of movement and in some cases reduces tremors).
Parkinsonian syndromes due to encephalitis or cerebral arteriosclerosis
Inflammation of the brain or encephalitis can cause alterations in the brain nuclei that regulate the dopaminergic transmission, the movement and the nigrostriatal pathway. The use of levodopa is indicated in these cases.
Neuroleptic consumption
One of the most common side effects of neuroleptics or antipsychotics, especially typical or first generation, is the presence of extrapyramidal symptoms such as akathisia or tremors . This is produced by the blockade of the dopamine receptors in the nigrostriatal pathway (although the objective of the typical neuroleptics is the mesolimbic pathway, its action is nonspecific and also reaches other nerve pathways).
This is why it is common to use antiparkinson medication, among other substances levodopa (sometimes mixed with other substances such as carbidopa) in order to reduce these symptoms.
- You may be interested: "Extrapyramidal symptoms: types, causes and treatment"
Poisoning: carbon monoxide or manganese
Another indication of levodopa is in the therapeutic use in order to treat damage to the nervous system caused by manganese or carbon monoxide poisoning .
Side effects of levodopa
As with all psychotropic drugs, the consumption of levodopa can have more or less serious side effects. However, we are usually faced with mild discomfort and in many cases temporary. The most likely are typical of many other medications: nausea, vomiting, decreased appetite, tremors and nervous contractions , blurred vision, darkening of urine, insomnia or sedation, fatigue and agitation or restlessness.
There may also be behavioral changes such as hypersexuality, and paranoid ideations and depressive symptoms may appear. They can also appear edemas, urinary problems (excess or deficit), weakness, headaches or numbness.
In addition to this we must bear in mind that more serious problems may arise that require immediate attention such as seizures, persistent diarrhea, arrhythmias, suicidal ideation or allergic reactions.
Contraindications and precautions
In addition to the secondary symptoms, we must bear in mind that it is not always 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 worsen it). As well the joint use of this medicine and MAO inhibitors should be avoided , medication against hypertension, anesthetics (can generate arrhythmia) or anticonvcolvulsvos or tranqulizantes (the effect is reduced).
Finally, patients with glaucoma, minors, pregnant, subjects with psychosis (unless it is applied as antiparkinsonian before consumption of neuroleptics) or heart problems should not consume it or if necessary should consult with their doctor what precautions to use .
