Propranolol

WHAT IS IT?

Propranolol is a beta-blocker (β-blocker) medication. It is a nonselective antagonist of beta receptors (blocks both β1 and β2 receptors equally). It is classified as a class II antiarrhythmic medication.

Simplified overview of propranolol mechanism of action in the body (source)
Simplified overview of propranolol mechanism of action in the body (source)

The result of giving beta-blockers like propranolol is: 

  • Decreased heart rate
  • Decreased cardiac contractility
  • Decreased AV conduction (increased PR interval)
WHEN DO WE USE IT?

Cardiac usages: 

  • Supraventricular tachycardia
  • Ventricular rate control for atrial fibrillation
  • Ventricular rate control for atrial flutter
  • Hypertension
  • Tetralogy of Fallot (hypercyanotic spells)

Neurological usages: 

Psychological usages: 

  • Performance anxiety

Other usages: 

  • Thyroid storm: this medication block the perisperhal conversion of T4 to T3.
WHEN DO WE AVOID USING IT?

Asthma: patients with asthma should generally avoid nonselective beta-blockers as this will constrict the respiratory system.

Asthmatic patients should generally avoid medications that block the beta-2 receptors in the lungs (source)
Asthmatic patients should generally avoid medications that block the beta-2 receptors in the lungs (source)

In the setting of α1-agonism: it is thought that when the alpha 1 receptors are agonized giving a beta blocker can be dangerous because they can cause a hypertensive crisis (due to the unopposed vasoconstriciotn that might occur). Examples α1-agonism include:

HOW IS IT ADMINISTERED?

This medication can be administered either orally or by IV.

Source
Source
WHAT ARE THE SIDE EFFECTS/TOXICITY?

General: dizziness

Cardiac: CHF exacerbation

Respiratory: nonselective beta blockers like propranolol can cause bronchospasm due to  β2 receptor blockade.

Psychological: mood changes (depression), memory loss/confusion (especially in the elderly)

Other: erectile dysfunction/impotence (lack of β2 receptor mediated vasodilation)

HOW DO WE TREAT OVERDOSE?

β-blocker overdose is treated with saline, atropine, and glucagon.

ANYTHING ELSE TO KEEP IN MIND?

Ending of “-olol” is reserved for the β-blocker class of medications

FURTHER READING

DynaMed

UpToDate

 

Page Updated: 07.20.2016