Cardiac glycosides
This information is not intended for purposes of treatment without physician.
Description of the pharmacological group
Cardiac glycosides
Cardiac glycosides include the medicines of plant origin, which possess the ability to increase the force of the heart contractions. This group of means sufficiently widely is used in the clinical practice for treating the heart insufficiency, as a rule, of chronic.
The plants, which contain cardiac glycosides, include the different types of digitalis (Digitalis of purpurea L., Digitalis of lanata of ehrh. and other), lychnis (Adonis of vernalis L. and other), lily of the valley (Convallaria of majalis L.), Grecian silk vine (Periploca of graeca L.), the different types of erysimum (Erysimum of canescens of roth., Erysimum of cheiranthoides L. and other), strophanthus (Strophanthus of gratus, Strophanthus Kombe), oleander (Nerium of oleander L.), bear's-foot (Helleborus of purpurascens W. et k.), jute is dolichocarpous (Conchorus of olitorius L.), Kharg shrub (Gomphocarpus of fruticosus A. Br.) and other
The mechanism of the action of cardiac glycosides is connected with the activity of the ferment of adenosinee triphosphatase, or ATPase, which ensures the transport of the ions of potassium, sodium, calcium. They normalize the disrupted energy and electrolyte metabolism in the heart muscle, they contribute to mastering creatin phosphate, to use by a heart ATF, the content of glycogen in the heart muscle increases and by others as a result this appears the therapeutic effect of cardiac glycosides, which is evinced by the following changes in the work of the heart:
1) the force of the heart contractions is strengthened; systole becomes more energetic and shorter on the time; the impact volume of the blood increases;
2) the diastole becomes more prolonged, which occurs as a result reflexes with the interoceptors of reflexogenic zones and strengthening of the influence of the vagus nerve on the heart. Into the cameras of heart enters more than the blood. The rhythm of heart becomes less frequent;
3) retarding the conductivity of pulses is manifested with respect to the atrioventricular of unit and beam.
Under the effect of cardiac glycosides increases diuresis, which is connected in essence with an improvement in the blood circulation.
The symptoms of poisoning by cardiac glycosides appear with the overdose (introduction of large doses, cumulation and others): bradycardia, and increase in the excitability of heart contributes to the appearance of a tachycardia, extrasystoles, and then during the disturbance of atrioventricular conductivity can arise fibrillation of ventricles, stopping of heart.
Treatment with cardiac glycosides begins from the large doses, assigned patient during 3-6 days (phase of saturation), before obtaining of the clear therapeutic effect: the decrease of developments of stagnation, elimination of edemas, shortness of breath, improvement in the general state of patient. Then they decrease the dose and the supporting doses (phase of maintenance), which ensure effective and safe therapy, are assigned upon consideration of the specific features of patient. Complications with the designation of cardiac glycosides can begin as a result overdose, with the cumulation, the scarcity of potassium in the organism, the individual increased sensitivity to glycosides; they are manifested in the form different arrhythmias (it is required EKG- control), sometimes dyspeptic disorders (nausea, vomiting) and other in the case of the overdose of cardiac glycosides should be assigned the preparations of potassium: Panangin, Asparcam, potassium chloride in the powder (with the caution - is caused the irritation of mucosa of gastrointestinal tract, up to the pittings; therefore better to introduce the sterile solution of potassium of chloride intravenously).
Classification
cardiac glycosides are subdivided into three groups:
1. Glycosides of the long-term effect, during introduction of which maximum effect with the internal administration is developed after 8-12 hours and continues to 10 days and more. The action after 30-90 minutes begins during the intravenous introduction, maximum effect appears after 4-8 hours. This group includes glycosides of digitalis purple (Lanoxin, digitoxin and other), which possess expressed cumulation.
2. Glycosides of the average duration of the actions, during introduction of which maximum effect appears after 5-6 hours and it lasts during 2-3 days. The action after 15-30 minutes begins during the intravenous introduction, maximum effect appears after 2-3 hours. This group includes glycosides of digitalis woolly (preload, lanatoside and other), which possess moderate cumulation. This property possess also glycosides of digitalis of rusty and lychnis.
3. Glycosides of rapid and short action - preparations of special aid. They introduce only intravenously, effect begins after 7-10 minutes. Maximum action is manifested after 1-1,5 hours and it lasts to 12-24 hours. This group includes glycosides of strophanthus and lily of the valley, which do not practically possess cumulative properties.