What is the conversion from oral Metoprolol (beta blocker) to intravenous (IV) Metoprolol?

From the Guidelines

When converting metoprolol from oral to intravenous (IV) dosing, use a 2.5:1 ratio, meaning 100 mg oral metoprolol is equivalent to approximately 40 mg IV metoprolol. For patients already on oral metoprolol who need temporary IV therapy, administer 25% of the total daily oral dose as an IV dose every 6-12 hours. For example, if a patient takes 100 mg oral metoprolol twice daily (200 mg total daily dose), give 50 mg IV metoprolol every 12 hours. When administering IV metoprolol, give it as a slow IV push at 1-2 mg/minute to minimize risks of hypotension and bradycardia. Monitor blood pressure and heart rate closely during and after administration. The difference in bioavailability explains this dosing conversion - oral metoprolol undergoes significant first-pass metabolism in the liver, resulting in only about 40-50% of the dose reaching systemic circulation, while IV administration bypasses this first-pass effect, making it more potent at lower doses. When converting back to oral therapy, resume the previous oral dose once the patient can take medications by mouth 1.

Some key points to consider when using metoprolol include:

• The initial IV dose of metoprolol can be given in 5-mg increments by slow intravenous administration (5 mg over 1 to 2 min), repeated every 5 min for a total initial dose of 15 mg 1.
• In patients who tolerate the total 15-mg IV dose, oral therapy can be initiated 15 min after the last intravenous dose at 25 to 50 mg every 6 h for 48 h 1.
• The target resting heart rate is 50 to 60 beats per minute unless a limiting side effect is reached 1.
• Selection of the oral agent should include the clinician's familiarity with the agent 1.

It is essential to monitor patients closely during IV metoprolol administration and adjust the dose as needed to minimize the risk of adverse effects 1.

In summary, when converting metoprolol from oral to IV dosing, a 2.5:1 ratio should be used, and the dose should be administered slowly to minimize risks of hypotension and bradycardia. Monitoring of blood pressure and heart rate is crucial during and after administration. The patient's previous oral dose should be resumed once they can take medications by mouth. It is also important to consider the patient's individual needs and adjust the dose accordingly. By following these guidelines and considering the patient's specific situation, healthcare providers can ensure safe and effective use of metoprolol.

From the FDA Drug Label

The mean elimination half-life of metoprolol is 3 to 4 hours; in poor CYP2D6 metabolizers the half-life may be 7 to 9 hours. In most subjects (extensive metabolizers), less than 10% of an intravenous dose are excreted as unchanged drug in the urine In poor metabolizers, up to 30% or 40% of oral or intravenous doses, respectively, may be excreted unchanged; The study thus was able to show a benefit from the overall metoprolol regimen but cannot separate the benefit of very early intravenous treatment from the benefit of later beta-blocker therapy Nonetheless, because the overall regimen showed a clear beneficial effect on survival without evidence of an early adverse effect on survival, one acceptable dosage regimen is the precise regimen used in the trial Because the specific benefit of very early treatment remains to be defined however, it is also reasonable to administer the drug orally to patients at a later time as is recommended for certain other beta-blockers.

The FDA drug label does not provide a direct conversion from metoprolol oral to IV. However, based on the information provided, metoprolol can be administered both orally and intravenously, and the choice of route may depend on the clinical situation.

• The intravenous dose is not explicitly stated in the label, but it is mentioned that patients treated with metoprolol received the drug both very early (intravenously) and during a subsequent 3-month period.
• The oral dosage used in clinical studies ranged from 100 to 450 mg daily for hypertension and 100 to 400 mg daily for angina pectoris.
• It is also mentioned that the mean elimination half-life of metoprolol is 3 to 4 hours, which may be relevant when considering the timing of oral and intravenous doses 2. However, without explicit guidance on conversion, a conservative approach would be to consult other reliable sources or clinical guidelines for specific recommendations on metoprolol oral to IV conversion.

From the Research

Metoprolol Oral to IV Conversion

• The provided studies do not directly address the conversion of metoprolol from oral to IV administration.
• However, the studies discuss the use of metoprolol in various cardiovascular conditions, such as heart failure, atrial fibrillation, and hypertension 3, 4, 5.
• One study compares the efficacy of different beta-blockers, including metoprolol, in the management of long QT syndrome types 1 and 2, but does not provide information on oral to IV conversion 6.
• Another study investigates the use of ivabradine in patients with poor heart rate control after beta-blocker use, but does not specifically address metoprolol oral to IV conversion 7.

Available Information on Metoprolol

• Metoprolol is a selective beta1-adrenergic antagonist that has been extensively used in the treatment of heart diseases, such as heart failure and atrial fibrillation 3.
• The drug has been shown to be associated with significant mortality and morbidity benefits in the treatment of heart failure 3.
• Metoprolol is also used in the management of hypertension, although its role as a first-line treatment has been controversial 4.

Limitations

• The provided studies do not provide direct evidence for metoprolol oral to IV conversion.
• Further research is needed to establish the safety and efficacy of metoprolol oral to IV conversion in various clinical settings 5.