Which calcium channel blocker is administered via intravenous route with a rapid onset of action?

Verapamil is the calcium channel blocker that is administered intravenously and has a rapid onset of action. This characteristic makes it particularly useful in acute clinical settings, such as in cases of rapid ventricular rate associated with atrial fibrillation or flutter. When given intravenously, verapamil can quickly achieve therapeutic blood levels, leading to immediate effects on heart rate and myocardial contractility.

In contrast, other options may not be suitable for IV administration or do not have the same rapid onset. For instance, while nifedipine is used for hypertension and angina, it is typically given orally and does not have the same rapid effects as verapamil when administered via the intravenous route. Amlodipine also has a delayed effect, as it is intended for once-daily oral dosing. Diltiazem, while it can be given intravenously, generally has a slower onset compared to verapamil in acute situations. Therefore, verapamil stands out due to its rapid therapeutic action when given via an IV route.