Propranolol Injectable Formulation
Yes, propranolol is available as an intravenous (IV) injectable formulation at a concentration of 1 mg/mL, specifically indicated for acute management of cardiac arrhythmias and urgent rate control. 1
FDA-Approved Injectable Formulation
- Propranolol Hydrochloride Injection, USP is supplied as a sterile solution containing 1 mg of propranolol hydrochloride per mL in water for injection. 1
- The pH is adjusted with anhydrous citric acid to maintain stability. 1
- This formulation is intended exclusively for intravenous administration, not intramuscular use. 1
Clinical Applications of IV Propranolol
Acute Cardiac Arrhythmias
- For atrial fibrillation with rapid ventricular response, the recommended IV dose is 0.15 mg/kg administered over 1 minute, which can be repeated every 2 minutes as needed, up to a maximum of 3 doses. 2
- The onset of action following IV administration is approximately 5 minutes, making it suitable for urgent rate control situations. 2
Emergency Thyrotoxicosis Management
- When urgent surgical preparation is required in hyperthyroid patients, a single IV dose of 0.15 mg/kg achieves rapid beta-blockade within less than 1 hour, providing prompt control of tachycardia. 3
Pharmacokinetic Considerations
- The IV half-life of propranolol is 2.4 hours, which is shorter than the oral immediate-release half-life of 3-6 hours. 3
- IV administration bypasses first-pass hepatic metabolism, resulting in 100% bioavailability compared to the variable 30-50% bioavailability seen with oral formulations. 4, 5
Safety Monitoring for IV Administration
Before administering IV propranolol, screen for absolute contraindications: second- or third-degree heart block, decompensated heart failure, cardiogenic shock, severe bradycardia, and severe hypotension. 2, 3
- Monitor heart rate and blood pressure immediately before administration and every 30 minutes for 2-4 hours after the dose. 2
- Watch for signs of excessive beta-blockade including heart rate below 50 beats/min, systolic blood pressure below 90 mm Hg, new or worsening dyspnea, and marked fatigue. 3
Important Clinical Caveats
- IV propranolol is reserved for acute situations requiring rapid beta-blockade; it is not appropriate for chronic management, which should utilize oral formulations. 2
- The IV formulation should never be combined with non-dihydropyridine calcium channel blockers (diltiazem, verapamil) due to markedly increased risk of severe bradycardia and heart block. 3
- In patients with diabetes or history of hypoglycemia, IV propranolol can mask adrenergic warning signs of low blood glucose, necessitating close glucose monitoring. 3, 6