Propranolol Extended Release to Immediate Release Conversion
For a patient requiring propranolol extended release 180 mg daily, the equivalent immediate release dose is 180 mg daily, divided into multiple doses (typically 60 mg three times daily or 45 mg four times daily).
Dose Equivalence
- The total daily dose remains the same when converting between propranolol extended release and immediate release formulations 1.
- Extended release propranolol 180 mg once daily should be converted to immediate release propranolol 180 mg total daily dose, divided into 2-4 administrations 1.
Recommended Dosing Schedule
- Divide the 180 mg total daily dose into either:
- 60 mg three times daily (every 8 hours), or
- 45 mg four times daily (every 6 hours) 1.
- The immediate release formulation requires divided dosing due to its shorter half-life of 3-6 hours compared to the extended release half-life of 8-10 hours 1.
Pharmacokinetic Differences
- Extended release propranolol has 30-50% lower bioavailability than immediate release formulations, but this is compensated by the controlled absorption maintaining therapeutic levels throughout 24 hours 2.
- Immediate release propranolol produces higher peak concentrations but requires multiple daily doses to maintain consistent beta-blockade 2, 3.
- The extended release formulation maintains relatively constant plasma concentrations without the marked peaks and troughs seen with immediate release 3.
Clinical Considerations
- When switching formulations, monitor heart rate and blood pressure closely during the transition period 1.
- The immediate release formulation may require dose adjustment based on clinical response, as the pharmacokinetic profile differs despite equivalent total daily dosing 2.
- Common adverse effects to monitor include bradycardia, hypotension, bronchospasm, and fatigue 1.
Important Contraindications
- Do not use propranolol in patients with AV block greater than first degree, SA node dysfunction (without pacemaker), decompensated heart failure, cardiogenic shock, or severe reactive airway disease 1.