mode of action
Last reviewed 01/2018
Verapamil is a class IV antiarrhythmic drug which impedes calcium transport across the myocardial and vascular smooth muscle cell membrane.
Effects:
- prolongs the slow component of the action potential and so prolongs the effective refractory period
- acts mainly at the SA and AV nodes - impairs conduction at these points
- negative ionotrope - diltiazem may be an alternative if this is a problem
- causes peripheral vasodilatation in smooth muscle so reducing cardiac load
- the combined effects of reducing cardiac load and of reducing myocardial contractility reduces myocardial oxygen requirements