What is the oral (po) to intravenous (iv) conversion for Metoprolol (Lopressor)?

From the Guidelines

When converting metoprolol from oral to intravenous (IV) dosing, the recommended IV dose is 2.5–5 mg bolus over 2 min, with up to 3 doses, as stated in the 2023 ACC/AHA/ACCP/HRS guideline for the diagnosis and management of atrial fibrillation 1. This guideline provides the most recent and highest quality evidence for metoprolol dosing. The oral maintenance dose of metoprolol tartrate is 25–200 mg, twice daily, and the elimination half-life is 3–4 hours. For metoprolol succinate, the oral maintenance dose is 50–400 mg daily or twice daily in 3–7 divided doses, with an elimination half-life of 3–7 hours. Key points to consider when converting metoprolol from oral to IV dosing include:

• The IV dose should be administered as a slow push over 1-2 minutes per 5 mg dose
• Careful monitoring of heart rate and blood pressure is necessary
• The maximum recommended IV dose is not explicitly stated for metoprolol tartrate in the provided guideline, but it is 2.5–5 mg bolus over 2 min, with up to 3 doses
• Patients may require dose adjustments based on their clinical response, hemodynamic stability, and the presence of hepatic impairment, which affects metoprolol metabolism. It is essential to note that the provided guidelines 1 are from 2014, which are older than the 2023 guideline 1, and therefore, the most recent guideline should be prioritized. In clinical practice, it is crucial to prioritize the most recent and highest quality evidence, such as the 2023 ACC/AHA/ACCP/HRS guideline 1, to ensure optimal patient outcomes in terms of morbidity, mortality, and quality of life.

From the FDA Drug Label

In patients who tolerate the full intravenous dose (15 mg), initiate metoprolol tartrate tablets, 50 mg every 6 hours, 15 minutes after the last intravenous dose and continued for 48 hours. Start patients who appear not to tolerate the full intravenous on metoprolol tartrate tablets either 25 mg or 50 mg every 6 hours (depending on the degree of intolerance) 15 minutes after the last intravenous dose or as soon as their clinical condition allows.

The po to iv conversion for metoprolol is not directly provided, but the label does provide information on transitioning from iv to po.

• The dose for transitioning from iv to po is 50 mg orally every 6 hours for patients who tolerate the full iv dose.
• For patients who do not tolerate the full iv dose, the dose is either 25 mg or 50 mg orally every 6 hours, depending on the degree of intolerance 2. To convert from po to iv, the information provided is not sufficient to make a direct conversion.

From the Research

Metoprolol PO to IV Conversion

• The provided studies do not directly address the conversion of metoprolol from oral (PO) to intravenous (IV) administration 3, 4, 5, 6, 7.
• However, it is known that metoprolol tartrate and metoprolol succinate are two different formulations of the drug, with metoprolol succinate being a controlled-release formulation 3.
• A 100-mg metoprolol controlled/extended-release tablet contains 95 mg of metoprolol succinate and is considered to have equivalent activity of 100 mg metoprolol tartrate 3.
• The studies provided focus on the pharmacokinetic and pharmacodynamic properties of metoprolol succinate, as well as its efficacy in treating hypertension, heart failure, and atrial fibrillation 3, 4, 5, 6, 7.
• There is no direct information on the conversion of metoprolol from PO to IV administration in the provided studies.
• In general, when converting a drug from oral to intravenous administration, the dosage and frequency of administration may need to be adjusted due to differences in bioavailability and pharmacokinetics.
• It is recommended to consult a reliable clinical resource or a healthcare professional for guidance on converting metoprolol from PO to IV administration, as this information is not provided in the studies 3, 4, 5, 6, 7.