Pharmacotherapeutic group: Electrolyte solutions. ATC code: B05XA07
Mechanism of action
Calcium is an essential ion necessary for the normal function of many biological processes in the body, such as nerve impulse conduction, synaptic transmission, hormone secretion, cardiac automaticity, mitotic activity, excitation-contraction coupling in muscles, and blood coagulation. Calcium is also a major intracellular mediator required for the full activity of enzymes.
The role of calcium in the regulation of tissue excitability probably involves regulation of cell membrane permeability to Na+ and K+ ions. The muscle action potential stimulates the release of calcium ions from the sarcoplasmic reticulum and activates contraction. A moderate decrease in calcium concentration can significantly lower the excitability threshold, resulting in tetanic spasms and other disorders.
Calcium is an indispensable ion for excitation-contraction coupling in cardiac muscle tissue, as well as for the conduction of electrical impulses in certain areas of the heart, particularly in the AV node region. Depolarisation of myocardial fibres opens voltage-dependent calcium channels and causes slow inward currents that form the plateau of the action potential. These currents allow permeation of a sufficient quantity of calcium ions to release further ions from the sarcoplasmic reticulum and thereby trigger contraction. Within the cardiovascular system, hypocalcaemia manifests with the following symptoms: hypotension, cardiac insufficiency, dysrhythmias (bradycardia, ventricular fibrillation), and diminished response to medicinal products whose mechanisms of action involve calcium (noradrenaline, digoxin, dopamine).
Calcium plays an important role in maintaining mucosal membrane integrity, cell adhesion, and also the function of cell membranes themselves. It is required for exocytosis and therefore plays an important role in stimulating secretion in most exocrine and endocrine glands. The release of catecholamines from the adrenal medulla, neurotransmitters at synapses, histamine from mast cells, etc., depends on calcium ions.
⚠️ Warnings
Intravenous calcium preparations are irritant to veins, therefore they must be diluted in 50–100 ml of 5% glucose solution.
Calcium must be administered with caution in patients receiving digitalis glycosides, as hypercalcaemia predisposes to digitalis toxicity. Optimal therapy requires frequent monitoring of serum calcium, magnesium, phosphorus, potassium, and creatinine levels, as well as assessment of electrocardiographic and haemodynamic status.
Calcium chloride is acidifying, therefore it is not suitable for treating hypocalcaemia in patients with renal insufficiency and acidosis.
The product must not be administered intramuscularly (including into the myocardium) or paravenously due to the risk of necrosis.
Calcium may cause hepatic necrosis in neonates when administered via the umbilical vein.
