Calcium antagonists

Question 1

What are the generic and brand names for calcium antagonists?

Answer 1

• Amlodipine – dihydropyridine calcium channel blockers
• Diltiazem – benzothiazepine
• Verapamil – phenylalkylamine

Question 2

What is the method of action for calcium antagonists?

Answer 2

• Class 4 antiarrhythmic agents
• Reduces Ca2+ entry into cardiac and vascular cells
• Ca2+ responsible for vasoconstriction and tensing of smooth muscle therefore this is counteracted = lowering blood pressure – more so with dihydropyridine calcium channel blockers
• Ca2+ is also responsible for myocardial contraction so the rate is reduced by suppressing cardiac conduction – more so with calcium channel blockers

Question 3

What are the indications for calcium channel blockers?

Answer 3

• Hypertension
• Stable angina
• Supraventricular tachycardias – STV, AF and atrial flutter

Question 4

What are the contraindications for calcium channel blockers?

Answer 4

• Poor left ventricular function – verapamil/diltiazem
• AV nodal conduction delay
• Unstable angina – amlodipine
• Severe aortic stenosis – amlodipine

Question 5

What are the side effects of calcium channel blockers?

Answer 5

• Ankle swelling – amlodipine/diltiazem
• Flushing – amlodipine/diltiazem
• Headaches – amlodipine/diltiazem
• Palpitations – amlodipine/diltiazem
• Constipation – verapamil
• Bradycardia - verapamil/diltiazem
• Heart block - verapamil/diltiazem
• Cardiac failure - verapamil/diltiazem

Question 6

What are the interactions with calcium channel blockers?

Answer 6

• Beta blockers – cause heart failure, bradycardia, asystole

Question 7

How are calcium channel blockers eliminated?

Answer 7

Kidney