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 to not be synthesized as much as it should, making it necessary to use external mechanisms such as drugs to increase its levels. One of these frequently used drugs is levodopa In this article we will talk precisely about it.
Levodopa or L-dopa is a medication or psychotropic drug which has been isolated from dopa, the metabolic precursor of dopamine, which in turn is derived from tyrosine (like the rest of the catecholamines including norepinephrine) 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 obtained directly from the diet. inside the body It is degraded by the enzyme monoamine oxidase or MAOI which allows its synthesis and levels to be regulated.
Used externally as a medication, it can address an absence of dopamine in the brain, as it can cross the blood-brain barrier (unlike dopamine itself) and degrade and transform into dopamine thanks to the decarboxylase enzyme. This makes it possible to treat problems derived from the deficiency of this last neurotransmitter as occurs with many motor alterations.
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 penetrate the brain. However, levodopa, its immediate precursor, does have this ability. This drug will subsequently be transformed into dopamine in the striatum of the basal ganglia thanks to the decarboxylation produced by dopaminergic neurons, which will ultimately end up increasing dopamine levels in the brain.
levodopa It is applied together with inhibitors of peripheral action such as carbidopa which allows levodopa not to be degraded during its passage through the digestive tract and to 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 medicine is Parkinson’s disease. This disorder is characterized by a degeneration of the substantia nigra and the basal ganglia produced by a deficit in the synthesis of dopamine. The well-known parkinsonian tremors appear, at rest, motor slowing and postural and movement problems, as well as facial inexpression.
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 generate alterations in the brain nuclei that regulate dopaminergic transmission, 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 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 target of typical neuroleptics is the mesolimbic pathway, its action is nonspecific and also reaches other nervous pathways).
For this reason, the use of antiparkinsonian medication is common, using, among other substances, 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 its therapeutic use to treat damage to the nervous system caused by from manganese or carbon monoxide poisoning
Levodopa Side Effects
As with all psychotropic drugs, the consumption of levodopa can have more or less serious side effects. However, in general we are dealing with mild and in many cases temporary discomfort. The most likely are typical of many other drugs: nausea, vomiting, decreased appetite, tremors, and nervous twitches blurred vision, darkening of urine, insomnia or sedation, fatigue, and agitation or restlessness.
Behavioral alterations such as hypersexuality may also appear, and paranoid ideations and depressive symptoms may appear. Edema, urinary problems (excess or deficit), weakness, headaches or numbness may also appear.
In addition, it must be taken into account that there may be more serious problems that require immediate attention such as seizures, persistent diarrhea, arrhythmias, suicidal ideation or allergic reactions.
Contraindications and precautions
In addition to the secondary symptoms, it must be taken into account that it will not always be advisable to use this drug. Among its many contraindications are mainly those cases in which one suffers from malignant melanoma (since it can activate the tumor and make it worse). Also The joint consumption of these medications 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 when taking neuroleptics) or heart problems should not consume it either or, if necessary, they should consult with their doctor what precautions to use..
