From the Guidelines
When converting metoprolol from intravenous (IV) to oral dosing, a 2.5-5 mg IV bolus is equivalent to 25-200 mg oral dose, given twice daily, as per the 2023 ACC/AHA/ACCP/HRS guideline for the diagnosis and management of atrial fibrillation 1. To determine the equivalent oral dose, consider the IV dose administered and the patient's response to treatment. For example, if a patient received a 2.5 mg IV bolus of metoprolol, the equivalent oral dose would be approximately 25-50 mg, given twice daily. Key points to consider when converting metoprolol from IV to oral dosing include:
- The elimination half-life of metoprolol tartrate is 3-4 hours, which may impact the timing of oral dosing 1.
- Metoprolol succinate has a longer elimination half-life of 3-7 hours, which may allow for once-daily dosing 1.
- The oral maintenance dose of metoprolol can range from 25-200 mg, given twice daily, depending on the patient's response to treatment and the presence of any comorbidities 1. It is essential to monitor the patient's heart rate, blood pressure, and overall clinical response when converting from IV to oral metoprolol to ensure the therapeutic effect is maintained.
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 conversion from IV to PO metoprolol is as follows:
- Patients who tolerate the full IV dose (15 mg) can be started on 50 mg PO every 6 hours.
- Patients who do not tolerate the full IV dose can be started on 25 mg or 50 mg PO every 6 hours, depending on the degree of intolerance. 2
From the Research
Metoprolol Conversion PO IV
- The conversion of metoprolol from oral (PO) to intravenous (IV) administration is crucial in certain clinical settings, such as cardiac surgery or heart failure management.
- According to a study published in Circulation 3, intravenous administration of metoprolol is more effective than oral administration in preventing atrial fibrillation after cardiac surgery.
- The dosage of metoprolol used in the IV group was 1 to 3 mg/h, while the oral group received 25 mg twice per day to 50 mg 3 times per day.
- Another study published in The Annals of pharmacotherapy 4 discussed the pharmacology and pharmacokinetics of extended-release metoprolol succinate, but did not provide direct information on PO to IV conversion.
- A review of metoprolol's pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy 5 mentioned that optimum treatment of hypertension and angina pectoris with metoprolol is achieved through dose titration within the therapeutic range, but did not address IV administration specifically.
- The study on beta-blockers for heart failure 6 provided information on initiating doses and target doses for metoprolol succinate, but did not discuss IV administration or conversion from PO.
- A study on metoprolol succinate combination in the treatment of hypertension 7 mentioned that 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, but did not provide information on IV administration or conversion.
Key Points to Consider
- When converting metoprolol from PO to IV, the dosage should be adjusted according to heart rate, as mentioned in the study published in Circulation 3.
- The IV dosage of metoprolol can range from 1 to 3 mg/h, while the oral dosage can range from 25 mg twice per day to 50 mg 3 times per day.
- It is essential to consider the patient's individual response to metoprolol and adjust the dosage accordingly, regardless of the route of administration.