The nurse knows that which diuretic is most frequently combined with an antihypertensive drug?

Alpha blockers such as doxazosin (Cardura) are known to cause a pronounced first-dose orthostatic hypotensive effect, especially after the initial administration. This sudden drop in blood pressure can result in dizziness, syncope, or fainting, particularly when moving from lying to standing. Administering the first dose at bedtime helps minimize the risk of injury from falls or fainting episodes during this adjustment period.

Rationale for correct answer:

A. Alpha blockers such as doxazosin (Cardura):
Alpha-adrenergic blockers work by causing vasodilation through the relaxation of smooth muscle in blood vessels, leading to a decrease in peripheral vascular resistance. However, the initial dose can cause a marked drop in blood pressure, known as the “first-dose phenomenon.” Giving the first dose at bedtime helps reduce the client’s risk of falling or fainting, as they are in a supine position when the drug takes effect.

Rationales for incorrect answers:

B. Diuretics such as furosemide (Lasix):
Diuretics increase urine output, which can lead to nocturia if taken at bedtime. Therefore, they are typically administered in the morning to prevent nighttime interruptions and maintain patient safety.

C. ACE inhibitors such as captopril (Capoten):
Although ACE inhibitors can cause hypotension, especially after the first dose, the effect is generally less abrupt than that seen with alpha blockers. Timing of administration is flexible and not specifically recommended at bedtime unless the client experiences dizziness.

D. Vasodilators such as hydralazine (Apresoline):
Vasodilators may cause hypotension, but the first-dose phenomenon is not as pronounced as with alpha blockers. These drugs are usually given as scheduled, with blood pressure monitoring rather than timing adjustment.

Take-home points:
• Alpha blockers cause a marked first-dose hypotensive effect, requiring the initial dose to be given at bedtime.
• Administering the first dose at night reduces the risk of dizziness, syncope, and falls.
• Monitor blood pressure closely after the first dose and educate patients to rise slowly from bed or sitting positions.

Propranolol (Inderal) is a non-selective beta-adrenergic blocker used to manage hypertension, angina, and arrhythmias. It works by blocking both beta-1 and beta-2 receptors, which reduces heart rate and cardiac output. However, blocking beta-2 receptors in the lungs causes bronchoconstriction, making this drug contraindicated in clients with asthma or other obstructive pulmonary diseases.

Rationale for correct answer:
A. Asthma
Propranolol blocks beta-2 receptors in bronchial smooth muscle, leading to bronchospasm and airway constriction, which can precipitate a life-threatening asthma attack. For clients with asthma or COPD, a cardioselective beta-blocker (like metoprolol or atenolol) is preferred, as these primarily target beta-1 receptors in the heart with less effect on the lungs.

Rationales for incorrect answers:
B. Diabetes
Although propranolol can mask symptoms of hypoglycemia such as tachycardia, it is not an absolute contraindication. Caution is needed, and diabetic clients should monitor their blood glucose closely.

C. Angina
Propranolol is commonly prescribed to treat angina pectoris because it reduces myocardial oxygen demand by lowering heart rate and contractility. It is not contraindicated for this condition.

D. Tachycardia
Propranolol is often used to control tachycardia, especially those related to anxiety or hyperthyroidism, by decreasing sympathetic stimulation of the heart. It is therefore therapeutic, not contraindicated.

Take-home points:

• Propranolol is contraindicated in clients with asthma due to the risk of bronchospasm.
• Non-selective beta-blockers affect both the heart and lungs, whereas cardioselective ones primarily target the heart.
• Clients with diabetes taking propranolol require careful glucose monitoring because symptoms of hypoglycemia can be masked.