Professional and Linguistic Assessments Board (PLAB) Practice Exam

Which of the following is an adverse effect of calcium channel blockers?

1. Bradycardia

2. Hypertension

3. Hyperkalemia

4. Weight gain

The correct answer is: Bradycardia

Bradycardia occurs as a result of the effects of calcium channel blockers on the heart. These medications work by inhibiting the influx of calcium ions through L-type calcium channels, which affects the conduction system of the heart and can lead to a slower heart rate. This effect is particularly pronounced with certain types of calcium channel blockers, especially non-dihydropyridines like verapamil and diltiazem, which have more direct effects on the cardiac tissues compared to dihydropyridines like amlodipine that primarily target vascular smooth muscle. In contrast, hypertension would not be an adverse effect since calcium channel blockers are primarily used to lower blood pressure by relaxing blood vessels. Hyperkalemia, or high potassium levels, is not typically associated with calcium channel blocker use, as they do not have a direct effect on potassium metabolism. Weight gain is also generally not considered a common adverse effect of calcium channel blockers; in fact, some individuals might experience weight loss due to improved exercise tolerance and reduction of peripheral edema.