From the Guidelines
To convert 100 mg daily intravenous (IV) metoprolol to an oral (PO) dose, the equivalent oral dose would be 100-200 mg daily, considering the dosing recommendations from the most recent guidelines. According to the 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation 1, the usual oral maintenance dose of metoprolol tartrate is 25-100 mg twice daily, and for metoprolol XL (succinate), it is 50-400 mg once daily. This suggests that the oral dose of metoprolol may need to be higher than the IV dose to achieve the same clinical effects. The oral metoprolol can be given as either immediate-release tablets (typically divided twice daily) or as extended-release tablets (once daily). When switching from IV to oral metoprolol, the oral dose should be administered after the last IV dose, and patients should be monitored for heart rate and blood pressure to ensure the oral dose provides similar clinical effects as the IV formulation.
- Key considerations for the conversion include:
- The patient's individual response to the medication
- The presence of any contraindications or cautions, such as signs of heart failure, low output state, or reactive airways disease 1
- The need for close monitoring of heart rate and blood pressure after conversion to ensure the oral dose provides similar clinical effects as the IV formulation
- The most recent and highest quality study, the 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation 1, provides the best evidence for the conversion of IV to oral metoprolol, and its recommendations should be prioritized in clinical practice.
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. Thereafter, the maintenance dosage is 100 mg orally twice daily
The oral (PO) equivalent of 100mg daily of metoprolol given intravenously (IV) is not directly stated in the label, as the IV dose is given as bolus injections of 5 mg. However, the label does provide information on the transition from IV to PO dosing.
- The maintenance dosage is 100 mg orally twice daily, which is equivalent to 200 mg daily. Since the question asks for the equivalent of 100mg daily of metoprolol given IV, and the label does not provide a direct conversion, no conclusion can be drawn about the PO equivalent of 100mg daily of metoprolol given IV 2.
From the Research
Metoprolol Equivalent Doses
To determine the oral (PO) equivalent of 100mg daily of metoprolol given intravenously (IV), we need to consider the bioavailability of metoprolol when administered orally.
- The bioavailability of oral metoprolol is approximately 50% due to first-pass metabolism 3.
- When given intravenously, metoprolol bypasses first-pass metabolism, resulting in a higher bioavailability.
- A study comparing the pharmacokinetics of immediate-release (IR) metoprolol and controlled-release/extended-release (CR/XL) metoprolol found that the peak plasma levels of metoprolol IR 50 mg were comparable to those of CR/XL 200 mg 4.
- However, there is no direct information in the provided studies to calculate the exact oral equivalent of 100mg daily of metoprolol given intravenously.
Pharmacokinetics and Pharmacodynamics
- Metoprolol CR/XL 200 mg was associated with a more pronounced suppression of heart rate than metoprolol IR 50 mg 4.
- The MERIT-HF study found that metoprolol CR/XL once daily, in addition to standard therapy, lowered mortality in patients with decreased ejection fraction and symptoms of heart failure 5.
- The study also found that the target dose of metoprolol CR/XL was 200 mg once daily, with doses up-titrated over 8 weeks 5.
Limitations
- There is limited information available to directly answer the question of the oral equivalent of 100mg daily of metoprolol given intravenously.
- Further research is necessary to define an exact oral dosage of metoprolol that is equivalent to 100mg daily given intravenously.