Diltiazem

Benzothiazepine derivative.

Indications

Angina pectoris, hypertension, SVT.

Mechanism

Inhibits influx of extracellular Ca++ by blocking slow Ca channels, and so reduces myocardial contractility (negatively inotropic) and peripheral resistance.

Contraindications

Heart block, ventricular tachycardia, WPW or LGL with AF.

Drug interactions

Amiodarone (sinus arrest). β-blockers (may unmask sick sinus syndrome).