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 medication works, as well as its characteristics, adverse effects and the possibility of combining it with other medications.
Selegiline is an MAOI (selective MAO inhibitor) antidepressant, specifically inhibits the degradation of MAO-B (enzymes that break down dopamine). That is, it acts 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 It has a hypothetical neuroprotective effect due to its ability to inhibit the formation of free radicals from dopamine metabolism and, in addition, a mild symptomatic effect. In the elderly it is of little use since it produces confusion and nervousness.
The method 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, it degrades dopamine.
That is, selegiline works by increasing the concentration of dopamine in the brain specifically in the nigro-striatal brain segments, and as a consequence improves motor function (which is why it is indicated in Parkinson’s disease).
Selegiline It 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 isolated 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 may help people with Parkinson’s disease by lowering the dose of levodopa/carbidopa needed to control symptoms, lengthening the effect of levodopa/carbidopa, and thus increasing the length 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.
Contraindications
Selegiline is contraindicated when there is hypersensitivity to it; also concomitantly with: SSRIs (as it can trigger hypertensive crises), dual serotonin and norepinephrine reuptake inhibitors, 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: HBP, hyperthyroidism, pheochromocytoma, narrow-angle glaucoma, prostatic adenoma with the appearance of residual urine, 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 levodopa dose 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
When faced with monotherapy (sole 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, however, we are dealing with a combined treatment of levodopa with selegiline, the following may appear: states of excitement, insomnia, feelings of tiredness, drowsiness, vertigo, headache anxiety, restlessness, dyskinesias, arterial hypotension, edema, lack of appetite, nausea, hallucinations, constipation and, in rare cases, states of mental confusion, psychosis, urination disorders and dyspnea.
All of these adverse effects can be reduced in part by a reduction in the levodopa dose, which is possible under combination therapy with selegiline.
