Conversion of Metoprolol IV Tartrate 5 mg to PO Dosing
The equivalent oral dose of metoprolol tartrate for a patient receiving 5 mg IV is 50 mg PO, based on a 1:10 conversion ratio from IV to oral dosing. 1
Evidence-Based Conversion Ratios
The conversion from intravenous to oral metoprolol follows a well-established ratio:
- A 10:1 ratio is used when converting from IV to oral metoprolol dosing
- 5 mg IV metoprolol tartrate is approximately equivalent to 50 mg oral metoprolol tartrate 1
Pharmacokinetic Considerations
When converting from IV to oral metoprolol, several factors should be considered:
- Metoprolol tartrate is an immediate-release formulation requiring twice-daily (BID) dosing
- The oral bioavailability of metoprolol tartrate is approximately 50% due to first-pass metabolism
- This reduced bioavailability necessitates the 10:1 conversion ratio from IV to oral dosing
- Peak plasma concentrations occur 1-2 hours after oral administration 1, 2
Dosing Recommendations
When transitioning from IV to oral metoprolol tartrate:
- For a patient receiving 5 mg IV metoprolol tartrate, prescribe 50 mg PO metoprolol tartrate
- Standard oral dosing of metoprolol tartrate is typically 25-100 mg BID 1
- If once-daily dosing is preferred for adherence reasons, consider converting to metoprolol succinate (extended-release) at an equivalent daily dose 1, 3
Clinical Pearls and Caveats
- Monitor heart rate, blood pressure, and symptoms when transitioning from IV to oral therapy
- If the patient has renal or hepatic impairment, consider starting with a lower oral dose
- For patients with heart failure, initiate at a lower dose (12.5-25 mg BID of tartrate) and gradually titrate up 1, 4
- If the patient has difficulty with twice-daily dosing, metoprolol succinate (extended-release) can be given once daily at the same total daily dose 1, 3
Alternative Formulation Considerations
If considering a switch to metoprolol succinate (extended-release):
- 50 mg of metoprolol tartrate twice daily (100 mg total daily dose) is equivalent to 100 mg of metoprolol succinate once daily
- Metoprolol succinate provides more consistent plasma concentrations over 24 hours 1, 2, 3
- Once-daily dosing with metoprolol succinate may improve medication adherence compared to twice-daily regimens with metoprolol tartrate 1
Remember that the goal of beta-blocker therapy is to improve symptoms and quality of life while preventing adverse cardiovascular outcomes, with target heart rates typically 60-80 bpm at rest and less than 110 bpm with moderate activity.