Propranolol: 6 things you should know
Medically reviewed by C. Fookes, BPharm Last updated on Sep 14, 2018.
1. How it works
- Propranolol is a medicine that may be used in the treatment of some heart conditions and also to reduce tremor and prevent migraines. It exerts its effects by blocking beta receptors. There are two types of beta receptors, beta-1 receptors (located in the heart) and beta-2 receptors (located in the bronchioles of the lungs and the arteries of skeletal muscle).
- Propranolol blocks beta-1 receptors in the heart which slows the heart rate and decreases how hard the heart has to work to pump blood around the body, decreasing blood pressure.
- Propranolol has a "nonselective" action - which means that it also blocks beta-2 receptors in the bronchioles, which can cause a narrowing of the bronchioles which may cause breathing difficulties in people with pre-existing lung disease.
- Propranolol also has a membrane-stabilizing effect at higher dosages which can affect the electrical impulses of the heart, although is not thought to contribute much to its antiarrhythmic properties.
- Experts are not sure how propranolol works to prevent migraines or tremors.
- Propranolol belongs to a class of medicines known as beta adrenergic blockers or beta blockers.
- May be used to treat high blood pressure (hypertension), either alone or in combination with thiazide diuretics or other medicines for hypertension.
- May improve the symptoms of angina and increase a person with angina's capacity to exercise.
- May be used in the prevention of migraine headache.
- May improve symptoms of hypertrophic subaortic stenosis; however, will not change the course of the disease.
- Approved for the treatment of essential tremor (ET). Reduces tremor amplitude but not frequency; complete suppression of tremor is rare. Appears to work best for high-amplitude, low-frequency ET.
- Generic propranolol is available.
If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:
- Low blood pressure (which may be felt as dizziness upon standing); cold extremities or Raynaud's phenomenon (characterized by numbness and cold in the fingers and toes in response to cold temperatures or stress); tiredness or lack of energy; a slow heart rate and irritability are some of the more commonly reported side effects. Elderly people may be more sensitive to these effects.
- Propranolol is more likely than some other beta blockers (such as atenolol) to cause vivid or unusual dreams.
- Abrupt discontinuation has been associated with exacerbation of angina, and rarely, heart attacks. Only discontinue on a doctor's advice and reduce dosage gradually over a few weeks.
- May not be suitable for some people including those with certain heart or respiratory conditions, or in those with kidney or liver disease. Propranolol may interfere with glaucoma screening tests because it can reduce intraocular pressure.
- Can mask the symptoms of hypoglycemia (low blood sugar) or hyperthyroidism (high thyroid levels), so must be used with caution in people with diabetes or thyroid disease.
- May aggravate peripheral circulatory disorders, increase blood cholesterol levels, and decrease HDL cholesterol.
- May cause a number of unwanted heart-related effects and may affect breathing, so response must be monitored. May cause low blood sugar (hypoglycemia) even in people without diabetes and interfere with some laboratory tests.
- Can interact with a number of different drugs including several drugs used to treat heart conditions, NSAIDs, antidepressants, anesthetic agents, warfarin, and those metabolized through CYP2D6, 1A2, or 2C19 metabolic pathways.
Notes: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. For a complete list of all side effects, click here.
- May be taken with or without food. Take exactly as directed. Do not increase or decrease the dosage without your doctor's advice.
- Swallow extended-release capsules whole: do not prise apart or chew.
- Should always be used as part of a comprehensive cardiovascular risk reduction program which includes diabetes management, smoking cessation, exercise, and other drug therapies. May be used in addition to other blood pressure lowering drugs.
- Seek immediate medical advice if you find it difficult to breathe.
- Talk to your doctor as soon as possible if any new numbness, pain, skin color changes or sensitivity occurs in fingers or toes.
- Call your doctor immediately if you develop a severe skin rash or painful blisters anywhere on your body.
- If you have diabetes, and you have been prescribed propranolol, be aware that it may mask some of the signs or symptoms of hypoglycemia (low blood sugar levels), such as heart palpitations and shakiness.
- Propranolol may also cause blood sugar levels to drop in people without diabetes, particularly after exercise or exertion or in those who have kidney disease. This may be felt as a light-headedness or dizziness.
6. Response and Effectiveness
- Peak concentrations are reached within six hours following administration of extended-release (ER) capsules; effects last for 24 hours following ER dosing so ER capsules may be given once daily.
- Propranolol is lipophilic, and is able to cross the blood/brain barrier (a semipermeable membrane that separates blood from the fluid surrounding the brain). This means it is more likely than some water-soluble beta blockers (such as atenolol) to cause side effects such as vivid or unusual dreams.
- When used for essential tremor, there is a wide variation in individual response, and effective dosages may range from 60mg to 320mg. May be used on a daily basis or as needed before or during social situations or planned events.
Propranolol [Package Insert]. Revised 01/2018. AvKARE, Inc. https://www.drugs.com/pro/propranolol.html
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use propranolol only for the indication prescribed.
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