Etacizin, 50 mg 50 pcs.

Tetracyzine is a class IC antiarrhythmic agent with long-lasting antiarrhythmic action. It inhibits the rate of rise of the action potential front (V_max), does not change the resting potential. Depending on the dose, it may decrease the duration of action potential. Does not significantly change the effective refractory periods of the ventricles and atria. Inhibits the fast incoming sodium current and, to a lesser extent, the slow incoming calcium current.

Tetracyzine slows the conduction of excitation through the myocardial conduction system. ECG shows prolongation of PR interval and QRS complex; ST interval, reflecting ventricular repolarization, is unchanged or tends to be shortened.

Tetracyzine increases myocardial fibrillation threshold. Unlike many antiarrhythmic agents, Etacizin does not cause a significant decrease in heart rate or prolongation of QT interval duration on ECG.

The antiarrhythmic effect usually develops on day 1 or 2 when taken orally; the duration of treatment depends on the form of arrhythmia and the effectiveness and tolerability of the drug.

Pharmacokinetics

In oral administration, it is quickly absorbed from the gastrointestinal tract and determined in the blood after 30-60 minutes. C_max in blood plasma is reached after 2.5-3 hours. Bioavailability is 40%. 90% is bound to plasma proteins. T_1/2 is 2.5 hours.

Parameters of pharmacokinetics of Etacizin are subject to significant individual fluctuations and require individual study in individual patients to determine the optimal blood plasma concentration of the drug. The drug is intensively metabolized during “first passage” through the liver. Some of the resulting metabolites have antiarrhythmic activity. Etacizine is excreted from the body by the kidneys as metabolites. Etacizine penetrates the placental barrier. It is excreted with breast milk.

Indications

Active ingredient

Composition

Active ingredient:

ethacizine (diethylaminopropionylethoxycarbonylamine-phenothiazine hydrochloride) 50 mg,

Ancillary substances:

Potato starch, 9.57 mg;

sucrose, 19.3 mg;

methylcellulose – 0.33 mg;

calcium stearate – 0.8 mg,

Shell:

sucrose, 37.695 mg; povidone, 0.753 mg; quinoline yellow dye (E104), 0.025 mg; sunset yellow dye (E110), 0.003 mg; calcium carbonate – 6.308 mg; magnesium hydroxycarbonate base – 3.678 mg; titanium dioxide (E171) – 0.665 mg; silicon dioxide – 0.827 mg; carnauba wax – 0.046 mg

How to take, the dosage

Ingestion, regardless of meals. The initial dose is 50 mg (1 tablet) 2 to 3 times daily. If the clinical effect is insufficient, the dose is increased (with obligatory ECG monitoring) to 50 mg 4 times a day (200 mg) or 100 mg 3 times a day (300 mg).

When sustained antiarrhythmic effect is achieved, maintenance therapy is given at individually adjusted minimum effective doses.

Interaction

It is contraindicated with other class IC antiarrhythmic drugs (morazizine, allapinin, propafenone) and IA (quinidine, procainamide, disopyramide, aymalin).

Tetracyzine should not be administered concomitantly with MAO inhibitors.

The combination of beta-adrenoblockers with Etacizin may increase the antiarrhythmic effect, especially in relation to arrhythmias provoked by exercise or stress.

Special Instructions

In the same way as other antiarrhythmic drugs, Etacizin may act arrhythmogenically. Therefore, when prescribing Etacizin, you should:

The risk factors of arrhythmogenic action of Etacizin are: organic heart disease (especially – previous myocardial infarction), decreased left ventricular ejection fraction, maximum drug doses. In addition, caution should be exercised in patients with liver disease. Alcohol should not be consumed during treatment with Etacizin.

At the time of therapy it is necessary to regularly monitor the patient’s condition and the function of the cardiovascular system (ECG, BP, echocardiography).

Impact on the ability to drive a car or perform work requiring increased speed of physical and mental reactions. Because of the risk of dizziness during treatment, it is not recommended to drive vehicles or to operate complex mechanisms requiring increased attention and ability to concentrate.

Contraindications

Side effects

System effects: sinus node arrest, AV blockade, intraventricular conduction disorders, decreased myocardial contractility, decreased coronary blood flow, arrhythmia (arrhythmogenic effect is most likely after myocardial infarction and in other types of cardiac pathology leading to decreased myocardial contractility and development of heart failure).

E ECG changes: prolongation of the PQ interval, dilation of the P wave and the QRS complex.

CNS disorders: dizziness, headache, staggering when walking or turning the head, light drowsiness; in some cases – diplopia, accommodation paresis.

Gastrointestinal disorders: nausea.

The side effects may decrease or disappear after 3-4 days of using the drug. They do not increase with long-term treatment with Etacizin, and they quickly disappear with discontinuation of the drug.

Side effects are dose-dependent and maximum doses of the drug should not be prescribed to avoid them.

Overdose

Tetracyzine has a low therapeutic latitude, so severe intoxication can easily occur (especially with the simultaneous use of other antiarrhythmic agents).

Symptoms: prolongation of PR intervals and expansion of the QRS complex, increased amplitude of T waves, bradycardia, sinoatrial and AV block, asystole, paroxysms of polymorphic and monomorphic ventricular tachycardia, reduced myocardial contractility, persistent BP decrease, dizziness, blurred vision, headache, gastrointestinal disturbances.

Treatment: symptomatic; Class IA and IC antiarrhythmic agents should not be used to treat ventricular tachycardia; sodium hydrogen carbonate can eliminate QRS complex dilatation, bradycardia, and arterial hypotension.