Cardiovascular (Cardioselective Beta-Blockers)

Question 1

Examples of drugs (Cardioselective Beta-Blockers)

Answer 1

• Bisoprolol

- Atenolol

Question 2

Mechanism of action (Cardioselective Beta-Blockers)

Answer 2

• Cardioselective beta-1-adrenoceptor antagonist.
• Preferentially blocks beta-1 receptors in cardiac and renal tissue.
• Inhibits sympathetic stimulation of the heart and renal vasculature.
• Blockade of the sino-atrial node reduces heart rate (negative chronotropic effect) and blockade of receptors in the myocardium depresses cardiac contractility (negative inotropic effect).
• Additionally, blockade of beta-1 adrenoceptors in renal tissue inhibits the release of renin, depressing the vasoconstrictive effects of the renin-angiotensin-aldosterone system.

Question 3

Indications (Cardioselective Beta-Blockers)

Answer 3

• Hypertension
• Angina
• Rate-control in atrial fibrillation
• Carvedilol or Bisoprolol may be used as part of supportive therapy for mild / moderate heart failure.

Question 4

Side-effects (Cardioselective Beta-Blockers)

Answer 4

• Bradycardia
• Hypotension
• Bronchospasm
• Fatigue (Can affect up to 10% of patients)
• Cold extremities
• Sleep disturbances
• Loss of hypoglycaemic awareness

Question 5

Important pharmacokinetics/pharmacodynamics (Cardioselective Beta-Blockers)

Answer 5

• Avoid higher doses and use with caution in patients with Asthmatic and COPD – risk of bronchospasm.
• Avoid in patients with history of frequent hypoglycaemia.
• Do not combine Beta-Blockers with rate-limiting Ca2+-Channel-Blockers (Verapamil / Diltiazem) in anti-hypertensive therapy, due to risk of heart-block.

Question 6

Patient information (Cardioselective Beta-Blockers)

Answer 6

• Compliance is important – Patients may stop beta-blockers if they do not feel any better. Remind them that hypertension is asymptomatic but nonetheless a dangerous risk factor that needs controlled.
• Fatigue and cold extremities are common side-effects.