Mechanism of action
The pharmacological profile of selegiline is based on its ability to selectively block monoamine oxidase type B. Under physiological conditions, this enzyme is primarily responsible for the inactivation of the neurotransmitter dopamine in the central nervous system.
By inhibiting MAO-B, the drug artificially slows down the process of enzymatic degradation of dopamine. This action unfolds directly in the dopaminergic neurons of the substantia nigra. As a result of slowed degradation, the concentration of the neurotransmitter is maintained at a stably high level, which helps compensate for its deficiency in parkinsonism.
Selegiline's interaction with levodopa is of particular clinical importance. The drug potently potentiates (enhances) the pharmacological effects of levodopa. Due to this synergism, it becomes possible to adjust the therapeutic regimen and safely reduce the levodopa dosage by an average of 30% while maintaining the necessary control over motor disorders.
Clinical application features
The strategy for prescribing the drug directly depends on the stage of the pathological process:
- Early stages: at the initial stages of Parkinson's disease, selegiline demonstrates high efficacy as monotherapy.
- Advanced stages: the main and most justified approach is combination therapy. Co-administration with levodopa allows achieving optimal symptom control.
Neuroprotective effect
In modern pharmacology, it is hypothesized that selegiline has the ability to delay the death of dopaminergic neurons. This neuroprotective potential has a clear pathogenetic rationale.
The natural oxidative metabolism of dopamine is inevitably accompanied by the secondary formation of aggressive molecules. By blocking this metabolic pathway, selegiline significantly reduces the production of free oxygen radicals. Reducing the oxidative load prevents further damage to sensitive cellular structures of the nervous tissue.
Side effects
Interference with the neurotransmitter balance may be accompanied by a number of adverse reactions from various body systems:
- Central nervous system (CNS): disturbances in concentration and episodes of confusion are possible.
- Cardiovascular system (CVS): development of arterial hypotension is characteristic.
- Gastrointestinal tract (GIT): nausea and vomiting are the most frequent manifestations.
It is easy to remember the drug's site of action through an association: SELEgiline SELEctively preserves dopamine by blocking MAO-B.
Class and exam questions
To which pharmacological group does selegiline belong?
The drug belongs to the group of selective inhibitors of the monoamine oxidase type B (MAO-B) enzyme.
For what purpose is selegiline prescribed concomitantly with levodopa?
It potentiates (enhances) the effect of levodopa by slowing down dopamine breakdown in the CNS. This is clinically beneficial as it allows reducing the levodopa dosage by approximately 30%.
How is the neuroprotective effect of the drug explained?
Selegiline inhibits the oxidative metabolism of dopamine, which leads to a decrease in the synthesis of free oxygen radicals. This prevents oxidative damage and death of dopaminergic neurons.
What else to study on this topic
- Biochemical features of the monoamine oxidase type B enzyme
- The role of substantia nigra neurons in movement regulation
- Mechanisms of free oxygen radical generation during dopamine metabolism
- Principles of dosage calculation in combination therapy with levodopa
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