Propranolol

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.

Upsides

     * 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.

Downsides

   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, [84]click here.

Bottom Line

   Propranolol is mainly used for blood pressure and angina control;
   however, it also has a role in migraine prevention and the treatment of
   essential tremor. Propranolol may cause vivid dreams and is not usually
   recommended for people with pre-existing breathing difficulties.

Tips

     * 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.

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.

References