Calcium channel blockers

This information is not intended for purposes of treatment without physician.

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Description of the pharmacological group

Antiarrhythmic medicines of the IV class

The preparations of this group possess anti-adrenergic properties and do not influence the membranes.

Antiarrhythmic medicines of the IV class includes the preparations from the group of the antagonists of the ions Ca²⁺ - verapamil and diltiazem. The antagonists of the ions Ca²⁺ have sufficiently wide spectrum of pharmacological activity, including they they possess the ability to block “slow” transmembrane ionic Ca²⁺- channels of L- type, located on the cellular membrane of the conducting cardiomyocytes of sinoatrial and atrioventricular units. This action of verapamil and diltiazem leads to the fact that they slow down the automatism of sinoatrial unit and conducting, it increases the refractory period of atrioventricular node.

Table. Characteristic of the antiarrhythmic means IV of the class

The basic properties of the antiarrhythmic medicines IV of class are given in the table. Besides this the antagonists of the ions Ca²⁺ (verapamil, diltiazem) suppress anomalous automatism and trigger activity, that appear, for example, with the overdose of cardiac glycosides.

On EKG under the action antiarrhythmics IV of class is lengthened the interval PQ.

In the clinical practice of verapamil and Cardizem they use for treating various forms of the supraventricular of tachycardia and tachyarrythmias, including for treating of blinking arrhythmia and trial flutter.

However, one should memorize that to patients, whose twinkling or flutter of atria developed against the background syndrome WPW, the antagonists of the ions Ca²⁺, including of verapamil, they were contrasted, since they can provoke the fibrillation of the ventricles of heart as a result of the acceleration of conducting pulses along the additional anomalous conducting ways. This phenomenon is caused by the fact that because of retarding of conducting pulses along the atrioventricular unit conducting pulses along the additional anomalous conducting ways is accelerated.

The preparations IV of group (verapamil, nifedipine (adalat) and others) inhibit the slow transmembrane ion current of calcium into the cells of myocardium, which contributes to reduction in the automatism of ectopic centers and influences the repeated entrance of excitation.

Antiarrhythmics of the fourth group are used for treatment of paroxysmal tachycardia, paroxysm of atrial fibrillation