Disopyramide

Mechanism of action:
Similar to quinidine

Actions:
It also possesses properties of class III agents.

It has same actions as that of quinidine but it is more pronounced in causing anti-muscarinic actions. It causes peripheral vasoconstriction and produces negative inotropic effects.

It causes a prominent decline in myocardial contraction in patients whose left ventricular function has already been impaired.

Therapeutic uses:
Ventricular arrhythmias

Pharmacokinetics:
It is taken orally and about 50 percent of the drug is excreted without any change through the kidneys. It has been found that about 30 percent of the drug is metabolized in the liver into mono-N-dealkylated metabolite.

Adverse effects:
It causes anticholinergic effects such as constipation, dry mouth, retention of the urine and blurred vision. It may also cause hypotension.

Contraindications:
It is contraindicated for patients with

1. 2nd or 3rd degree AV block
2. cardiogenic shock
3. severe uncompensated cardiac failure

Dosage:
It is given 300-800 mg daily in divided doses.