Is it acceptable to administer intravenous metoprolol tartrate (Metoprolol) to a patient already taking metoprolol succinate (Metoprolol) for a coronary computed tomography angiography (CTA) with a normal pulse rate?

From the Guidelines

It is generally acceptable to administer intravenous metoprolol tartrate for a coronary CT angiography (CTA) even if the patient is already taking metoprolol succinate and has a goal heart rate. For optimal coronary CTA imaging, a heart rate below 60-65 beats per minute is typically desired, and additional beta-blockade may be necessary to achieve this target despite chronic oral therapy. The IV metoprolol tartrate provides immediate heart rate control during the procedure, while the oral succinate formulation provides longer-term control. According to the 2014 AHA/ACC guideline for the management of patients with non-ST-elevation acute coronary syndromes 1, beta-adrenergic blockers are recommended for patients with normal LV function with NSTE-ACS, and it is reasonable to continue beta-blocker therapy in these patients.

When administering IV metoprolol tartrate, start with small incremental doses (typically 5mg IV every 5 minutes, up to a total of 15-20mg) while monitoring vital signs closely. Ensure the patient's blood pressure remains stable, as the combined effect of both medications could potentially cause hypotension. Also, confirm the absence of contraindications such as severe bradycardia, high-degree heart block, cardiogenic shock, or decompensated heart failure before administration. The different formulations (succinate vs tartrate) have different pharmacokinetics but the same active metabolite, allowing for their combined use when clinically indicated. Key considerations include:

• Monitoring vital signs closely during administration
• Starting with small incremental doses
• Ensuring the absence of contraindications
• Being aware of the potential for hypotension due to combined beta-blockade.

From the FDA Drug Label

In patients with severe intolerance, discontinue metoprolol tartrate Parenteral administration of metoprolol tartrate should be done in a setting with intensive monitoring During the intravenous administration of metoprolol tartrate injection, monitor blood pressure, heart rate, and electrocardiogram

The patient is already taking metoprolol succinate and her pulse rate is at goal. The FDA label does not provide direct information on switching from metoprolol succinate to metoprolol tartrate for a CTA of her coronaries.

• The label recommends initiating treatment with metoprolol tartrate in the early phase of acute myocardial infarction.
• It also recommends parenteral administration of metoprolol tartrate in a setting with intensive monitoring.
• However, it does not address the specific scenario of a patient already taking metoprolol succinate. Therefore, caution should be exercised when considering administering metoprolol tartrate through IV in this scenario, and the decision should be made on a case-by-case basis with careful monitoring of the patient's condition 2.

From the Research

Administration of Metoprolol Tartrate via IV

• The decision to administer metoprolol tartrate via IV to a patient already taking metoprolol succinate and with a pulse rate at goal should be made with caution, considering the patient's overall clinical status and the specific indications for the medication.
• According to 3, switching between β-blockers may be necessary due to changes in a patient's clinical status, but guidelines on how to best switch to a different β-blocker are lacking.
• The study 4 provides information on the pharmacodynamic and pharmacokinetic properties of metoprolol, but does not specifically address the administration of metoprolol tartrate via IV in patients already taking metoprolol succinate.
• The use of extended-release metoprolol succinate in chronic heart failure is discussed in 5, which highlights its efficacy in reducing mortality and morbidity, but does not provide guidance on IV administration of metoprolol tartrate.
• The comparison of metoprolol versus carvedilol after acute myocardial infarction in 6 does not address the specific question of administering metoprolol tartrate via IV in patients already taking metoprolol succinate.
• The relation of cardiovascular response to the hypotensive effect of metoprolol is discussed in 7, which provides insight into the mechanisms of metoprolol's effects on blood pressure and cardiac output, but does not specifically address the administration of metoprolol tartrate via IV.

Key Considerations

• The patient's pulse rate is already at goal, which may indicate that the current medication regimen is effective.
• The decision to administer metoprolol tartrate via IV should be based on a thorough assessment of the patient's clinical status and the specific indications for the medication.
• The potential benefits and risks of administering metoprolol tartrate via IV in this scenario should be carefully weighed, considering the patient's individual needs and medical history.