Molecule

Drug Groups

approved

Description

An antiarrhythmia agent used primarily for ventricular rhythm disturbances. [PubChem]

Indication

Used to treat irregular heartbeats (arrhythmias) and maintain a normal heart rate.

Pharmacology

Moricizine is used to treat irregular heartbeats (arrhythmias) and to maintain a normal heart rate. It acts on the heart muscle to improve the heart's rhythm. Moricizine has potent local anesthetic activity and membrane stabilizing effect. Decreases excitability, conduction velocity, and automaticity as a result of slowed atrioventricular (AV) nodal and His-Purkinje conduction. Decreases the action potential duration (APD) in Purkinje fibers; also decreases the effective refractory period (ERP) but to a lesser extent than the APD, so the ERP/APD ratio is increased. Decreases the maxiumum rate of Phase 0 depolarization (V max ), but does not affect action potential amplitude or maximum diastolic potential. Does not affect atrial, AV nodal, or left ventricular refractory periods and has minimal effect on ventricular repolarization (evidenced by the overall decrease in JT interval). Has no effect on sinoatrial (SA) nodal or intra-atrial conduction and only minimal effect on sinus cycle length and sinus node recovery time. In the Vaughan Williams classification of antiarrhythmics, moricizine is considered to be a class I agent. It has properties of class IA, IB, and IC agents but does not clearly belong to any of the three subclasses. It has less effect on the slope of phase 0 and a greater effect on action potential duration and effective refractory period than class IC agents.

Toxicity

Symptoms of overdose include vomiting, unconsciousness, and severe low blood pressure.

Affected Organisms

Biotransformation

Hepatic and extensive, to at least 26 metabolites, none accounting for as much as 1% of the administered dose. Two metabolites may be pharmacologically active but are present in extremely small quantities. Moricizine induces its own metabolism (it induces hepatic cytochrome P-450 activity).

Absorption

Well absorbed, absorption is complete within 2 to 3 hours. Significant first-pass metabolism results in an absolute bioavailability of approximately 38%. Administration within 30 minutes after a meal slows the rate, but does not affect the extent of absorption, although peak plasma concentrations are reduced.

Half Life

2 hours (range 1.5-3.5 hours).

Protein Binding

Approximately 95%.

Elimination

Less than 1% of orally administered Ethmozine? is excreted unchanged in the urine. Approximately 56% of the administered dose is excreted in the feces and 39% is excreted in the urine.

Distribution

* 300 L

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