Classification and Role in Therapy
In pharmacology, vasopressor agents are traditionally divided into two major groups based on their impact on systemic hemodynamics.
The first group comprises agents that increase both cardiac output and peripheral vascular tone (a typical representative is the $\alpha, \beta$-adrenomimetic epinephrine).
Angiotensinamidum belongs to the second group—agents that predominantly increase peripheral vascular tone. This hemodynamic group also includes $\alpha$-adrenomimetics (norepinephrine, phenylephrine), but angiotensinamide stands out due to its chemical nature: it is not a catecholamine derivative, but rather a drug with a polypeptide structure.
Mechanism of Action and Vascular Effects
The pharmacological target of the drug is angiotensin receptors located in the walls of arterioles.
Stimulation of these receptors leads to a rapid and extremely pronounced vasoconstrictor effect. It is important to note that in terms of pressor potency, angiotensinamide significantly exceeds epinephrine (adrenaline).
A key feature of the drug is its site-specific action. Vasoconstriction occurs unevenly: the most pronounced vascular narrowing is observed in the vascular beds of the internal organs, skin, and kidneys. This blood flow distribution profile must be considered when evaluating the risks of tissue ischemia during therapy.
Effects on Water-Electrolyte Balance
In addition to its direct effect on vascular smooth muscle, Angiotensinamidum exhibits significant hormonal activity.
The drug interferes with the endocrine system by stimulating the production of the mineralocorticoid aldosterone. The consequences of this hormonal shift include:
- Active retention of sodium ions in the body.
- Secondary water retention.
- A predictable increase in extracellular fluid volume.
This mechanism provides an additional contribution to maintaining elevated blood pressure.
Formulation and Administration Guidelines
The drug is available as a dry substance in vials containing 0.001 g (1 mg).
To administer, an infusion solution must be prepared strictly ex tempore (immediately prior to use).
Preparation and Administration Algorithm:
- The contents of one vial are dissolved in a large volume of liquid—1000 mL of 0.9% sodium chloride solution (normal saline) or 5% glucose solution.
- Administration must be performed exclusively intravenously.
- The infusion rate must be strictly controlled, ranging from 5 to 20 mcg per minute, depending on the patient's hemodynamic response.