The following statement is not true about sotalol:
**Core Concept**
Sotalol is a non-selective beta-blocker with additional anti-arrhythmic properties, primarily through its class III mechanism of action. It inhibits the potassium channel, thereby prolonging the repolarization phase of the cardiac action potential and increasing the effective refractory period.
**Why the Correct Answer is Right**
The correct answer is related to the pharmacological properties of sotalol. Sotalol's class III anti-arrhythmic effects are due to its ability to block the potassium channels, particularly the I_Kr (rapid component of the delayed rectifier potassium current) channel. This action prolongs the action potential duration and increases the QT interval. Additionally, sotalol has class II beta-blocking effects, which reduce sympathetic tone and heart rate.
**Why Each Wrong Option is Incorrect**
**Option A:** Sotalol is not a selective beta-1 blocker. It is a non-selective beta-blocker, which means it blocks both beta-1 and beta-2 receptors.
**Option B:** Sotalol is not primarily a class I anti-arrhythmic agent. It does not work by blocking sodium channels like class I agents do.
**Option C:** Sotalol does not primarily work through its alpha-1 blocking effects. Its anti-arrhythmic effects are primarily due to its class III mechanism of action.
**Clinical Pearl / High-Yield Fact**
Sotalol is associated with a risk of QT interval prolongation, which can lead to torsades de pointes. This is an important consideration when prescribing sotalol, especially in patients with pre-existing QT interval prolongation or those taking other medications that can prolong the QT interval.
**Correct Answer: C. Sotalol does not primarily work through its alpha-1 blocking effects.**