Origin and Chemical Structure
The primary and practically sole representative of this pharmacological group in clinical practice is vinpocetine.
Chemically, the drug is a semi-synthetic derivative of the natural alkaloid vincamine. The initial raw materials used to obtain these compounds are medicinal plants of limited distribution, specifically lesser periwinkle (Vinca minor L.) and Vinca erecta.
Molecular Mechanism of Action
The pharmacological effects of vinpocetine are based on several interrelated cellular processes:
- Myotropic spasmolytic effect: mediated by the drug's ability to inhibit the enzyme phosphodiesterase.
- As a result of this enzymatic blockade, cyclic adenosine monophosphate (cAMP) accumulates within the smooth muscle cells of the vascular wall.
- The accumulation of cAMP leads to relaxation of vascular smooth muscle and a subsequent decrease in vascular tone.
Hemodynamic and Rheological Effects
Unlike many classical vasodilators, vinca derivatives possess a unique vascular action profile:
- Selectivity: the drug predominantly dilates cerebral blood vessels without exerting a pronounced effect on systemic circulation in other vascular beds.
- Absence of the "steal" phenomenon: the drug does not redirect blood away from healthy tissues, but instead purposefully enhances blood supply specifically to ischemic areas suffering from oxygen deprivation.
- Improvement of microcirculation: achieved by reducing blood viscosity, decreasing platelet aggregation, and increasing erythrocyte deformability, allowing them to pass freely through the narrowest capillaries.
Metabolic Effects and Clinical Application
The neuroprotective and metabolic action of vinpocetine is expressed in protecting nerve cells from oxygen deprivation. The drug helps neurons utilize oxygen more efficiently, enhances glucose uptake, and shifts its oxidation toward the more energy-efficient aerobic pathway.
Main indications for use:
- Chronic cerebrovascular insufficiency.
- Recovery period following a stroke.
- Various neuropsychiatric disorders associated with cerebrovascular pathology.
- Vascular ophthalmic diseases.
- Hearing loss of toxic or vascular origin in otolaryngology.
Administration and Adverse Effects
The drug is administered orally in long-term courses, and when emergency care is required, intravenous infusion is used.
- Potential adverse effects:
- General reactions: moderate decrease in blood pressure, nausea, dizziness.
- Risks associated with rapid intravenous administration: tachycardia, extrasystoles, or slowing of intraventricular conduction.