Verapamil

Phenylalkylamine derivative.

Indicatons

Angina, hypertension, SVT, AF, atrial flutter.

Mechanism

Inhibits influx of extracellular Ca++ into myocardiocytes and vascular smooth muscle cells, by blocking slow Ca channels.

Adverse effects

Negatively intropic, so digoxin preferred to control rate in AF. May cause heart block. Prolongs QT interval. Bradycardia.

Contra-indications

Concurrent β-blocker administration. Sick sinus syndrome. Wolf-Parkinson-White or Lown-Ganong-Levine with AF (may provoke ventricular fibrillation).