Professional and Linguistic Assessments Board (PLAB) Practice Exam

Which medication is often used as a second-line treatment alongside phenoxybenzamine for pheochromocytoma?

1. Corticosteroids

2. Beta-blockers

3. Calcium channel blockers

4. Angiotensin receptor blockers

The correct answer is: Beta-blockers

In the management of pheochromocytoma, a tumor that secretes catecholamines leading to symptoms like hypertension, phenoxybenzamine is commonly used as a first-line treatment to control these symptoms by irreversibly blocking alpha-adrenergic receptors. When additional control of symptoms, particularly tachycardia and other cardiovascular features caused by excess catecholamines, is necessary, beta-blockers are often employed as a second-line treatment. Beta-blockers work by blocking the effects of catecholamines on beta-adrenergic receptors, thus reducing heart rate and myocardial contractility. This makes them particularly useful in patients who continue to experience significant cardiovascular symptoms despite adequate alpha-blockade with phenoxybenzamine. However, they should be introduced cautiously and typically administered only after adequate alpha-adrenergic blockade has been achieved to avoid exacerbating hypertension due to unopposed alpha-adrenergic stimulation. The other options listed, while they may have cardiovascular effects, do not directly address the management of symptoms related to pheochromocytoma in the same way. Corticosteroids are not standard treatment in this scenario, as they do not play a significant role in catecholamine management. Calcium channel blockers can help with hypertension but are not