Propranolol
A non-selective beta blocker used for high blood pressure, angina, migraine prevention, tremor, anxiety symptoms and an overactive thyroid.
Drug card
- Class
- Beta blocker
- How it works
- Blocking beta receptors, so the heart beats slower and less forcefully
- Used for
- High blood pressure
- Angina
- Migraine prevention
- Essential tremor
- Known for
- Narrowed airways (bronchospasm), asthma attacks
- Slow heart rate (bradycardia)
- Hidden warning signs of low blood sugar
- Its name
- -olol means a beta blocker
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does propranolol work?
Propranolol is non-selective, blocking both β1 and β2 receptors. It is highly lipophilic, so it enters the brain and reaches the fetus and breast milk, and heavy first-pass metabolism (mainly CYP2D6 and CYP1A2) lets only about 25% reach the circulation. In anxiety it blunts the bodily effects of epinephrine, such as shaking and a racing heart.
Like other beta blockers: They block β-adrenergic receptors, so epinephrine and norepinephrine act less: in the heart (β1) rate and force of contraction fall and AV conduction slows, and the kidneys release less renin. Cardioselective ones (atenolol, bisoprolol, metoprolol) act mainly on β1; non-selective ones also block β2 in airways and vessels; carvedilol and labetalol block α1 as well.
Uses
What is propranolol used for?
- High blood pressure
- Angina
- Migraine prevention
- Essential tremor
- Physical symptoms of anxiety
- Symptoms of an overactive thyroid (thyrotoxicosis)
Side effects
Side effects of propranolol
- Narrowed airways (bronchospasm), asthma attacksKnown forSerious
- Slow heart rate (bradycardia)Known for
- Hidden warning signs of low blood sugarKnown forSerious
- Low blood sugar, mainly in fasting childrenSerious
- Cold hands and feet (Raynaud type)
- Tiredness and lethargy
- Vivid dreams, nightmares and poor sleep
- Depression
- Worsening heart failureSerious
- Worsening AV blockSerious
- Angina or a heart attack if stopped suddenlySerious
- Erectile dysfunction
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Contraindicated in asthma, sinus bradycardia, heart block beyond first degree and cardiogenic shock.
- In thyrotoxicosis, stopping it suddenly can bring on thyroid storm.
- Pheochromocytoma: only after alpha blockade, since blocking β alone leaves α constriction unopposed.
- Inhibitors of CYP2D6, CYP1A2 or CYP2C19 can raise its levels.
Good to know: Being non-selective, it is the beta blocker also used outside the heart: for migraine, essential tremor, anxiety symptoms and thyroid overactivity.
Remember it
A way to remember it
One heart, two lungs: β1 for the heart, β2 for the lungs.
β1 receptors dominate in the heart and β2 receptors in the airways. Cardioselective beta blockers act mainly on β1, so they narrow the airways less than non-selective ones such as propranolol, though all need care in asthma.
A mnemonic widely used in teaching
Its name
-olol means beta blocker
Labetalol (-alol) and carvedilol (-dilol) are beta blockers that also block alpha-1 receptors. Stanozolol, an anabolic steroid, ends in -olol by chance.
- Every drug name stem
Its class
Beta blockers
Other beta blockers with a card:
Easily mixed up with alpha-1 blockers and non-dihydropyridine calcium channel blockers.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- Propranolol hydrochloride tablets: label (DailyMed)
- Propranolol (NCI Thesaurus)
- Propranolol (NHS)
- Beta blockers (NHS)
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Blood pressure
Propranolol is one of 27 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
Start Practicing