Calcium channel blockers Flashcards
What indications are they used for?
Hypertension
Control of angina
What is the mechanism of actions?
Reduces the concentration of calcium ions in vascular and cardiac cells, thereby causing relaxation and vasodilation in arterial smooth muscle and myocardial contractility in the heart.
What are the side effects?
Abdominal pain
Peripheral oedema
Headache
Flushing
Palpitations and tachycardia
Dizziness
What are the contraindications?
Heart failure as they can precipitate it (except amlodipine)
Cardiogenic shock
Unstable angina or recent MI avoid within 1 month of MI (except amlodipine)
What drugs do they interact with?
Theophylline- Increased concentrations when taking CCB
Grapefruit- increased exposure to CCB
Other antihypertensive drugs- increasked risk of hypotension
Clarithromycin and Erythromycin- Increased risk of CCB levels
What CCB are dihydropyridine?
Amlodipine
Felodipine
Lacidipine
Nifedipine
Lercanidipine
What CCB are non-dihydropyridines?
Verapamil
Diltiazem
What other indications can Diltiazem and Verapamil be used for?
Arrhythmias e.g. atrial fibrillation, supraventricular tachycardia and atrial flutter
What is the difference between dihydropyridines and non-dihydropyridines?
Dihydropyridines are selective for the vasculature
Non-dihydropyridines are selective for the heart
Diltiazem also has an effect on blood vessels
What side effects is commonly associated with verapamil?
Constipation
Bradycardia
Heart block
Cardiac failure
What side effects is commonly associated with Diltiazem?
As it has mixed vascular and cardiac actions it can cause any of the associated side effects of dihydropyridines and non-dihydropyridines (verapamil)
What important interactions does diltiazem and verapamil have?
Beta-blockers- should not be prescribed unless under specialist supervision
Colchicine- toxicity
Digoxin- toxicity
Amiodarone- increased risk of bradycardia, AV block, myocardial depression
How are they monitored?
Blood pressure
ECG for diltiazem and verapamil
Angina
