Propranolol

Propranolol is a non-selective beta-adrenergic receptor blocker with a broad range of clinical applications.

It is prescribed for the management of hypertension, angina pectoris, cardiac arrhythmias, essential tremor, migraine prophylaxis, anxiety-related tachycardia, phaeochromocytoma (as an adjunct), and the symptomatic control of thyrotoxicosis.

It is one of the most versatile and widely prescribed beta-blockers in clinical medicine.

Propranolol works by blocking beta-1 receptors in the heart, which reduces heart rate, contractility, and myocardial oxygen demand, and beta-2 receptors in the peripheral vasculature and bronchial smooth muscle.

This dual blockade accounts for both its therapeutic effects and certain precautions, particularly in patients with asthma or chronic obstructive pulmonary disease.

Propranolol is available in both immediate-release and modified-release formulations.

The immediate-release form is taken two to three times daily, while the modified-release capsule is taken once daily, offering convenience and improved adherence for long-term indications such as hypertension and migraine prophylaxis.

Take propranolol at the same time(s) each day, with or shortly after food, to improve absorption and reduce gastrointestinal discomfort. Swallow the tablets or capsules whole with water.

Do not stop taking propranolol suddenly, as abrupt withdrawal can cause rebound hypertension, worsening angina, or even myocardial infarction in susceptible individuals.

If discontinuation is needed, your prescriber will reduce the dose gradually over one to two weeks. Modified-release capsules should not be crushed or chewed.

Doses vary by indication. For hypertension: 80 mg twice daily initially, increased to a maximum of 320 mg daily. For angina: 40 mg two to three times daily, increased as needed.

For migraine prophylaxis: 40 mg two to three times daily (or 80 to 160 mg modified-release once daily). For anxiety: 40 mg one to three times daily.

For essential tremor: 40 mg two to three times daily, increasing up to 160 mg daily. Doses should be adjusted in hepatic impairment.

Common (1 in 10 to 1 in 100): fatigue, cold extremities, bradycardia, dizziness, nausea, diarrhoea, sleep disturbance including vivid dreams, impotence.

Uncommon (1 in 100 to 1 in 1,000): bronchospasm (particularly in patients with underlying airways disease), worsening of peripheral vascular disease, hypoglycaemia (particularly in fasting patients or those on insulin), depression, confusion, visual disturbances.

Rare (1 in 1,000 to 1 in 10,000): heart block, exacerbation of psoriasis, alopecia, thrombocytopenia. Beta-blockers may mask the warning signs of hypoglycaemia, notably tachycardia.

Do not stop propranolol abruptly. Propranolol should be used with extreme caution, if at all, in patients with asthma or severe COPD, as beta-2 blockade may precipitate bronchospasm.

It may mask the symptoms of hypoglycaemia in diabetic patients, particularly tachycardia.

Use with caution in patients with first-degree heart block, peripheral vascular disease, Raynaud's phenomenon, or hepatic impairment.

Inform your anaesthetist if you are taking propranolol before any surgery.

Propranolol is contraindicated in patients with uncontrolled heart failure, cardiogenic shock, second or third-degree heart block, sick sinus syndrome, severe bradycardia, untreated phaeochromocytoma (unless combined with an alpha-blocker), metabolic acidosis, severe hypotension, severe peripheral arterial disease, and asthma or a history of bronchospasm.

Hypersensitivity to propranolol or any excipient is also a contraindication.