Calcium-channel blockers: Nursing Pharmacology

Summary

Calcium channel blockers are medications primarily used to treat cardiac arrhythmias, hypertension, and angina. They work by blocking calcium channels in the heart and blood vessels, relaxing the muscles and reducing blood pressure. Two main types are dihydropyridines, which target blood vessels and are used for hypertension, and non-dihydropyridines, which focus on the heart for arrhythmias. Side effects may include dizziness, hypotension, and bradycardia. Nurses should provide education on proper medication use, avoiding grapefruit, and managing side effects like peripheral edema and constipation.

Takeaways

• 💊 Calcium channel blockers are primarily used to treat cardiac arrhythmias, hypertension, and angina pectoris, with additional uses for migraine prophylaxis and Raynaud phenomenon.
• 🔀 Calcium channel blockers are divided into two groups: dihydropyridines (e.g., amlodipine, nifedipine) and non-dihydropyridines (e.g., verapamil, diltiazem), each with different effects on the heart and blood vessels.
• 💉 Dihydropyridines, such as amlodipine and nifedipine, act more on the blood vessels, making them preferable for treating hypertension, while nimodipine is used to prevent cerebral vasospasm in subarachnoid hemorrhage.
• ❤️ Non-dihydropyridines, like verapamil and diltiazem, act more on the heart and are commonly used to treat angina and arrhythmias.
• 🧬 Calcium channel blockers work by blocking voltage-gated calcium channels, reducing calcium influx into cells, leading to muscle relaxation in both the heart and blood vessels.
• 🩸 By relaxing vascular smooth muscles, calcium channel blockers lower blood pressure and peripheral vascular resistance, which reduces afterload and improves oxygen delivery to the heart.
• 🧠 Common side effects include dizziness, hypotension, peripheral edema, and headaches, with dihydropyridines potentially causing reflex tachycardia and gingival hyperplasia.
• ⚠️ Non-dihydropyridines may lead to bradycardia, constipation, and hyperprolactinemia, and are contraindicated in clients with pre-existing bradycardia, heart block, or heart failure.
• 🍊 Grapefruit and grapefruit juice can increase calcium channel blocker levels and should be avoided, along with caution in clients with hepatic or renal disease.
• 🏥 Nurses should monitor heart rate, blood pressure, and lab results, and educate clients on proper medication use, side effect management, and lifestyle modifications for cardiovascular health.

Q & A

What are the primary uses of calcium channel blockers?

Calcium channel blockers are primarily used to treat cardiac arrhythmias, hypertension, and angina pectoris. They are also used to a lesser extent for migraine prophylaxis and the symptomatic treatment of Raynaud phenomenon.

What are the two main groups of calcium channel blockers?

The two main groups of calcium channel blockers are dihydropyridines and non-dihydropyridines. Dihydropyridines primarily affect blood vessels, while non-dihydropyridines have a stronger effect on the heart.

Can you give examples of dihydropyridine calcium channel blockers?

Examples of dihydropyridine calcium channel blockers include amlodipine, nicardipine, nifedipine, felodipine, and clevidipine. Nimodipine is another dihydropyridine that can cross the blood-brain barrier and is used for cerebral vasospasm.

How do non-dihydropyridines like verapamil and diltiazem differ from dihydropyridines?

Non-dihydropyridines like verapamil and diltiazem have a more potent effect on the heart, particularly in reducing heart rate and contractility. Verapamil is highly selective for cardiac calcium channels, while diltiazem is equally effective on both cardiac and vascular calcium channels.

How do calcium channel blockers work at the cellular level?

Calcium channel blockers block voltage-gated calcium channels, decreasing the amount of calcium entering the cell. This reduces the contraction ability of cardiac and vascular smooth muscles, resulting in muscle relaxation.

What are the effects of calcium channel blockers on the heart and blood vessels?

Calcium channel blockers relax vascular smooth muscles, reducing blood pressure and peripheral vascular resistance. They also relax coronary vessels, improving oxygen delivery to the heart and reducing the force of cardiac contractions, which lowers the heart's oxygen demand.

What are common side effects of dihydropyridine calcium channel blockers?

Common side effects of dihydropyridines include headache, dizziness, skin flushing, peripheral edema, and hypotension. In some cases, hypotension can trigger reflex tachycardia, and gingival hyperplasia may also occur.

What side effects are associated with non-dihydropyridines?

Non-dihydropyridines can cause bradycardia, constipation, and hyperprolactinemia due to their depressive action on the heart. They are contraindicated in clients with pre-existing bradycardia, heart block, or heart failure.

Why should clients taking calcium channel blockers avoid grapefruit?

Clients should avoid grapefruit because it can increase the blood levels of calcium channel blockers, potentially leading to toxicity.

What are important nursing considerations for clients prescribed calcium channel blockers?

Nursing considerations include monitoring baseline heart rate and blood pressure, reviewing lab results, educating clients on avoiding grapefruit, and teaching them how to manage side effects like hypotension and reflex tachycardia. Clients should also be educated on the importance of lifestyle modifications to support cardiovascular health.