What is the mechanism of action of selegiline/imidopir?

The mechanism of action of Selegiline/imidopyr (Selegiline) lies in its highly selective inhibition of monoamine oxidase B (MAO-B). MAO-B is an enzyme responsible for breaking down dopamine in the central nervous system, and one of the main pathological characteristics of patients with Parkinson's disease is the loss of dopaminergic neurons in the substantia nigra and the decrease in dopamine levels. Therefore, by inhibitingMAO-B, selegiline can reduce the degradation of dopamine, thereby prolonging its action time in the synaptic cleft and improving patients' motor symptoms such as tremor, stiffness and bradykinesia.

Unlike traditional dopamine replacement therapies (such as levodopa), selegiline does not directly supplement dopamine, but enhances the neurotransmitter effect by delaying endogenous dopamine metabolism, which allows it to be used as a single drug in the early stages of the disease to delay the progression of symptoms. In the middle and late stages of the disease, it is often used in combination with levodopa to reduce the "switching phenomenon" and fluctuations in drug efficacy, and improve patients' quality of life. Overseas studies have also found that selegiline produces a small amount of amphetamine-like metabolites after metabolism, which may partially explain its mild stimulant and antidepressant effects. Therefore, in some countries, low-dose selegiline is also being explored as an auxiliary treatment for severe depression.

In addition, selegiline has also received research attention in terms of neuroprotection. Studies have shown that the drug may protect neurons by reducing oxidative stress and inhibiting free radical production, thereby delaying the neurodegenerative process. This mechanism is still under continuous research, but it provides broader prospects for its clinical value. It should be noted that selegiline is selectively dose-dependent and mainly inhibits MAO-B at conventional doses. However, when the dose is increased, it may also have an effect on MAO-A, thus posing additional risks, especially in terms of diet and drug interactions. Therefore, its dosage is usually strictly controlled clinically to ensure that the mechanism of action is concentrated on MAO-B levels.

Reference: https://www.drugs.com/mtm/selegiline.html