Tablets "Digoxin" - cardiac glycoside. Cardiac stimulant, antiarrhythmic, cardiotonic drug.
Cardiac glycoside, found in digitalis woolly. It has a positive inotropic effect, which is associated with an inhibitory effect on the Na + -K + -ATP-azu of the cardiomyocyte membrane, which leads to an increase in the intracellular content of sodium ions and a decrease in potassium ions. As a result, an increase in intracellular calcium occurs, which is responsible for the contractility of cardiomyocytes, which leads to an increase in the force of contractions of the myocardium. Improves the functioning of the heart, while extending diastole. Systole becomes shorter and more energy efficient. As a result of the increase in myocardial contractility, the stroke volume and the minute volume increase. The end-systolic volume and the end-diastolic volume of the heart decrease, which, along with an increase in myocardial tone, leads to a decrease in its size and, thus, a decrease in myocardial oxygen demand. Reduces excessive sympathetic activity by increasing the sensitivity of cardiopulmonary baroreceptors. It has a negative chronotropic effect. Decrease in heart rate is largely associated with the cardio-cardiac reflex and occurs as a result of direct and indirect action on the regulation of heart rhythm. Direct action is to reduce the sinus node automatism. Of great importance in the formation of negative chronotropic action is a change in the reflex regulation of the heart rhythm: in patients with atrial tachyarrhythmia, the weakest impulses are blocked, the tone of the aorta and the carotid sinus increases, the mouth of the hollow veins and the right atrium (as a result of an increase in contractility of the myocardium of the left ventricle, its more complete emptying, reduction of pressure in the pulmonary artery and hemodynamic unloading and right heart), the elimination of Bainbridge reflex and reflex activation of sympatic system (in response to an increase in cardiac output).Reduces the speed of the excitation through the AV node and lengthens the effective refractory period, due to the increased activity of the vagus nerve, either by direct action on the AV node, or by sympatholytic effect. In medium doses, does not affect the speed and refractoriness of the conducting system of His-Purkinje. It has a direct vasoconstrictor effect, which is most clearly manifested in the event that a positive inotropic effect is not realized. At the same time, the indirect vasodilating effect (in response to an increase in the minute volume of blood and a decrease in excessive sympathetic stimulation of the vascular tone), as a rule, prevails over the direct vasoconstrictor effect, as a result of which the PRSS decreases. Increases ventilation in response to hypoxia induced stimulation of chemoreceptors. It contributes to the normalization of kidney function and increase diuresis. Has a pronounced ability to cumulation (material). In high doses, it increases the automatism of the sinus node, which leads to the formation of ectopic foci of excitation and the development of arrhythmia. In subtoxic or toxic doses, a positive bathmotropic effect is observed, manifested in the development of various (including life-threatening cardiac rhythm) due to electrical instability of cardiomyocytes, in which, due to blockade of the Na + -K + pump, the concentration of intracellular K + decreases and the concentration of intracellular Na + increases and there is a convergence of the resting potential with the threshold one.
After ingestion is rapidly and completely absorbed from the gastrointestinal tract. When taken after a meal, the rate of absorption decreases, the degree of absorption does not change. Quickly distributed in tissues. The concentration of digoxin in the myocardium is significantly higher than in plasma. T1 / 2 is 34-51 hours. Within 24 hours, about 27% of digoxin is excreted in the urine.
Chronic heart failure with decompensated valvular heart disease, atherosclerotic cardiosclerosis, myocardial overload in arterial hypertension, especially in the presence of a permanent form of tachysystolic atrial fibrillation or atrial flutter. Paroxysmal supraventricular arrhythmias (atrial fibrillation, atrial flutter, supraventricular tachycardia).
Dosage and administration
Recommended doses are strictly individual.Usually for adults, doses are used: for quick digitalization (by mouth) - from 0.75 mg to 1.25 mg in two or more doses, for slow digitalization - from 0.125 mg to 0.5 mg once a day for 7 days. Maintenance doses when taken orally - from 125 μg to 500 μg once a day. Sensitivity to cardiac glycosides (digoxin) is increased in elderly patients. Digoxin is taken on an empty stomach, i.e. 30-40 minutes before meals. Foods rich in proteins create a serious difficulty in achieving an appropriate therapeutic concentration of digoxin in the blood due to its chemical affinity for protein molecules. Foods rich in fats, accelerates the elimination of digoxin from the body by increasing the secretion of cholecystokinins, causing bile outflow, especially strong when taking fatty foods. Patients with impaired renal function, elderly, debilitated, patients with a pacemaker require careful selection of a dose of digoxin, because they increase the risk of toxic reactions. Children under 14 years old "Digoxin" is prescribed at a dose of 25-75 mg / kg body weight. Patients with impaired renal function "Digoxin" is prescribed in smaller doses: with glomerular filtration below 50 ml / min, 25-75% of the average dose should be used, with glomerular filtration below 10 ml / min - 10-25% of the average dose.