Propranolol, marketed in the United States under the trade names Inderal and Inderal LA, is a medication used to treat high blood pressure, chest pain and abnormal heart rhythms. In addition, it is used in the treatment and prevention of heart attack. Propranolol is also beneficial in the prevention of migraine headache. It is available by prescription in tablets, extended-release capsules, oral solution and injection.
Mechanism of Action
Within the human circulatory system, special receptors are called beta (β) receptors. These receptors affect heart rate, heart muscle contraction and the volume of blood the heart pumps each minute, called cardiac output. β-receptors within the kidney also exert effects on renin, a chemical involved in the body's blood pressure regulation.
Propranolol, a β-receptor antagonist, or "beta-blocker," reduces the effects of these receptors, resulting in lower blood pressure, more effective beating of the heart and relaxation of heart muscle.
The most common effect of propranolol is fatigue. Other mild central nervous system effects include headache, dizziness and insomnia. Patients experiencing more serious symptoms such as fever, confusion, vivid dreams, fainting or hallucinations should promptly notify their physician.
Cardiac effects are common and include a lower than desired heart rate, lower than desired blood pressure, heart failure, heart block, abnormal heart beat and chest pain. Patients with these symptoms should also notify their physician.
Shortness of breath may occur, as there are also β-receptors in the lung. Patients with chronic respiratory illness, such as asthma, emphysema or COPD should not use propranolol as it may worsen respiratory function or counteract certain respiratory medications. Any patients experiencing breathing difficulty or sore throat during propranolol use should contact their doctor.
Rare but serious skin effects, such as rash, skin peeling or blistering may occur and require immediate medical attention.
Less serious side effects include sexual dysfunction, nausea, vomiting, constipation and stomach cramps.
As with any medication, allergic response is possible. Difficulty breathing or swallowing, rash, itching or swelling could be signs of allergic reaction and require prompt medical attention.
β-blocker Use in Special Populations
β-blockers such as propranolol can mask the symptoms of low blood sugar and should be used with caution in diabetic patients. As mentioned, patients with respiratory disease should avoid propranolol and other β-blockers. Due to potentially harmful fetal effects, β-blockers should be avoided in the second and third trimesters of pregnancy. Patients with Reynaud's disease, a condition causing circulatory problems in the hands and feet, should also avoid β-blockers. β-blocker doses may require adjustment in patients with kidney disease.
Patients taking propranolol or other β-blockers should not abruptly discontinue the medication or a rebound spike in blood pressure could occur. Doses should be tapered over time under a physician's care. Patients on propranolol should consult a physician or pharmacist before taking over-the-counter medications, especially those for cold or flu. Until patients know how propranolol will affect mental function, they should not drive or operate machinery.
Several β-blockers are available on the US market. Side effect profiles vary among agents and from patient to patient. A patient unable to take propranolol may be able to tolerate a different β-blocker and may wish to discuss this option with his doctor.