Pharmacodynamics and Mechanism of Action
The therapeutic action of this drug is based on interference with adrenergic neurotransmission. Proxodolol possesses a combined mechanism of action:
- Primarily, it exhibits pronounced non-selective $\beta$-blocking activity. This means the drug blocks both $\beta_1$ and $\beta_2$ adrenergic receptors across various organs and tissues.
- Secondly, this activity is supplemented by a weak $\alpha$-blocking effect.
This specific combination of effects determines the breadth of the drug's clinical applications, as well as the profile of its adverse reactions when entering the systemic circulation.
Application in Ophthalmology
In ophthalmology, Proxodololum is used topically as eye drops. The primary indication for its use is open-angle glaucoma, a condition characterized by elevated intraocular pressure.
Its pressure-lowering mechanism is local and specific: through the local blockade of ocular $\beta$-adrenergic receptors, the drug causes a significant suppression of aqueous humor production. A reduction in intraocular fluid volume consequently leads to a decrease in intraocular pressure.
The pharmacokinetics of topical formulations are convenient for patients: a clinically significant pressure-lowering effect persists for 8–12 hours following a single instillation into the conjunctival sac.
Systemic Application
For systemic therapy, the drug is available in two main formulations: tablets for oral administration and a parenteral solution for injection.
The choice of formulation and route of administration depends on the clinical objective:
- Long-term therapy: Used in cardiology as a potent antihypertensive (for sustained blood pressure reduction) and antianginal (for the prevention of myocardial ischemia episodes) agent.
- Emergency care: The parenteral solution is administered intravenously. The primary goal of this therapy is the rapid and effective management of hypertensive crises.
Safety Profile and Contraindications
Like any non-selective $\beta$-blocker, proxodolol has several systemic adverse effects. When it enters the systemic circulation (including via systemic absorption of eye drops), the following undesirable reactions may occur:
- Cardiovascular system: bradycardia (marked reduction in heart rate) and hypotension.
- Smooth muscle: increased bronchial tone and increased myometrial tone (uterine smooth muscle).
Important: Due to its ability to increase bronchial tree tone (a consequence of $\beta_2$-receptor blockade), the drug has an absolute contraindication—bronchial asthma. Prescribing proxodolol to such patients is strictly prohibited due to the high risk of triggering life-threatening bronchospasm.