Propranolol

From Ask Dr Wiki

Contents 1 Mechanism of action 2 Therapeutic uses 3 Dose 4 Contraindications 5 Side effects 6 Drug interactions (not inclusive) 7 Comments 8 Pharmacokinetics

Mechanism of action

• Non-selective beta blockers antagonizes both beta₁ and beta₂ receptors thus inhibiting the effects of catecholamines on these receptors
• Cardiovascular effects include
• Reduced contractility
• Decreased heart rate
• Non-cardiovascular effects mediated through beta₂ blockade include potential to increase peripheral vascular resistance or bronchospasm

Therapeutic uses

• Hypertension
• Angina
• Essential tremor
• Arrhythmias
• Myocardial infarction
• Migraine headache
• Hypertrophic cardiomyopathy
• Antipsychotic-induced akathisia
• Portal hypertension
• Anxiety
• Acute panic
• Preventing esophageal varices bleeding

Dose

• Initial oral dose: 10 – 30 mg PO every 6-8 hours
• Maximum dose: 640 mg PO daily
• IV dosing
  • 1 mg slow IV push
  • Repeat every 5 minutes as needed

Contraindications

• Hypersensitivity to beta blockers
• Asthma
• Heart block greater than first degree
• Insulin dependent diabetics with frequent hypoglycemic episodes
• Overt heart failure/cardiogenic shock
• Severe bradycardia

Side effects

• Fatigue
• Bradycardia
• Heart block
• Bronchospasm
• Depression
• Lipid abnormalities
• May mask the symptoms of hypoglycemia
• Rebound effect with abrupt discontinuation
• Precipitation of heart failure
• Impotence

Drug interactions (not inclusive)

• Medications that slow AV nodal conduction such as
  • Digoxin
  • Diltiazem
  • Verapamil
  • Amiodarone
  • Other beta blockers
• Non-steroidal anti-inflammatory drugs
• Other medications that lower blood pressure
• Other medications that produce a decrease in contractility
• Medications that inhibit the CYP 2D6 enzyme

Comments

• Membrane stabilizing activity (MSA)
• Not clinically relevant
• MSA causes inhibition of catecholamine-induced renin release from the kidneys, thus inhibiting the renin-angiotensin-aldosterone system
• Patients should be informed that they should not stop taking beta blockers abruptly because this can lead to a rebound effect
• Diabetic patients should be informed that they need to monitor their blood glucose more frequently when starting a beta blocker since beta blockers can mask signs and symptoms of hypoglycemia
• Patients with bronchospastic lung disease should not receive beta blockers unless the benefits outweigh the risks

Pharmacokinetics

• Onset
  • Oral 1 - 2 hours
  • IV 2-5 minutes
• Half-life: 3 – 5 hours
• Elimination: hepatic
• Lipid solubility: high