Selegiline: uses and side effects of this drug

Parkinson's disease is a type of movement disorder that originates when neurons do not produce enough dopamine, thus causing different effects on movement. For its treatment it is mainly used selegiline, an MAOI antidepressant.

In this article we will see how this medicine works, as well as its characteristics, adverse effects and the possibility of combining it with other medicines.

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Selegiline: general characteristics

Selegiline is an MAOI (selective MAO inhibitor) antidepressant. inhibits the degradation of MAO-B (enzymes that break down dopamine). In other words, it works by increasing the concentration of dopamine (a natural substance necessary to control movements) in the brain, which leads to improvements in the patient's motor function.

On the other hand, selegiline has a hypothetical neuroprotective effect due to its ability to inhibit the formation of free radicals from the metabolism of the dopamine and, in addition, a slight symptomatic effect. In the elderly it is of little use as it causes confusion and nervousness.

The mode of administration of selegiline is orally (it must be swallowed with water and without chewing).

Mechanism of action

The mechanism of action of selegiline is the selective inhibition of MAO-B in the brain; MAO-B is an enzyme that catalyzes the oxidation of monoamines and the degradation of neurotransmitters -amines, in this case, degrades dopamine.

That is, the selegiline works by increasing the concentration of dopamine in the brain, specifically in the nigro-striated brain segments, and as a consequence improves motor function (which is why it is indicated in Parkinson's disease).

Therapeutic indications

selegiline is indicated for idiopathic Parkinson's disease. It can be used as monotherapy in the early stages of Parkinson's, or as an adjuvant to levodopa (with or without decarboxylase inhibitors). For its part, levodopa (L-DOPA) is the metabolic precursor of dopamine, and is considered the most effective single drug in the treatment of Parkinson's disease.

Thus, as we have seen, selegiline is used together with levodopa, and also with carbidopa (Sinemet).

Selegiline can help people with Parkinson's disease by lowering the dose of levodopa/carbidopa needed to control symptoms. symptoms, prolonging the effect of levodopa/carbidopa and thus increasing the period of time that levodopa/carbidopa will control symptoms.

At the moment selegiline is frequently used together with another MAOI, rasagiline, as an adjuvant in cases of advanced Parkinson's disease to treat motor symptoms.

• You may be interested in: "Parkinson's: causes, symptoms, treatment and prevention"

contraindications

Selegiline is contraindicated when there is hypersensitivity to it; also concomitantly with: SSRIs (since it can trigger hypertensive crises), dual inhibitors of serotonin and norepinephrine reuptake, tricyclic antidepressants, sympathomimetics, MAOIs, and opioids.

In addition, the administration of selegiline should be avoided. during the 5 weeks following the last administration of fluoxetine.

It is also contraindicated in cases of duodenal ulcer and/or gastric ulcer, as well as combined therapy with levodopa in: AHT, hyperthyroidism, pheochromocytoma, narrow-angle glaucoma, prostatic adenoma with residual urine appearance, tachycardia, arrhythmias, severe angina pectoris, psychosis, and advanced dementia.

Precautions

There are a number of concerns that we should be aware of in relation to selegiline. On the one hand, by combining selegiline treatment with the maximum tolerable dose of levodopa, involuntary movements and agitation may occur.

If this occurs, the dose of levodopa can be reduced by 30% (on average). Once we find the optimal dose of levodopa, the side effects of this combination therapy are less than those of levodopa therapy (alone or with a decarboxylase inhibitor).

Side effects

In monotherapy (single treatment) with selegiline, the following effects or adverse reactions have been detected in isolated cases: dry mouth, nausea, insomnia and arrhythmias; also increased values ​​of liver enzymes that do not present clinical relevance.

If, on the other hand, we are dealing with a combined treatment of levodopa with selegiline, the following may appear: states of arousal, insomnia, feelings of tiredness, drowsiness, vertigo, headache, anguish, restlessness, dyskinesias, arterial hypotension, edema, lack of appetite, nausea, hallucinations, constipation and, in rare cases, states of mental confusion, psychosis, disorders of the urination and dyspnea.

All these adverse effects can be partly reduced by lowering the levodopa dose, which is possible under selegiline combination therapy.