From the Guidelines
For PRN IV metoprolol for tachycardia, typical hold parameters include withholding the medication if the patient's heart rate is less than 60 beats per minute, systolic blood pressure is less than 100 mmHg, or if there are signs of heart failure or heart block. The standard dose is usually 2.5–5 mg bolus over 2 min; up to 3 doses as needed, as indicated in the 2023 ACC/AHA/ACCp/HRS guideline for the diagnosis and management of atrial fibrillation 1. Before administering, always check the patient's vital signs, particularly heart rate and blood pressure, and assess for contraindications such as severe bradycardia, heart block, cardiogenic shock, or decompensated heart failure. Some key points to consider when administering metoprolol include:
- The medication works by blocking beta-1 adrenergic receptors in the heart, reducing heart rate and cardiac output, which makes it effective for treating tachycardia but also explains why it can cause dangerous bradycardia or hypotension in vulnerable patients.
- Continuous cardiac monitoring is essential during administration.
- The elimination half-life of metoprolol tartrate is 3–4 h, which is an important consideration when determining the timing of repeat doses 1.
- It is crucial to be aware of the potential side effects, including bradycardia, hypotension, and heart failure, and to adjust the treatment plan accordingly. Given the potential risks and benefits, the decision to administer PRN IV metoprolol for tachycardia should be made on a case-by-case basis, taking into account the individual patient's clinical presentation, medical history, and current vital signs. In general, the goal of treatment is to reduce the heart rate to a range that is comfortable for the patient and minimizes the risk of complications, while also avoiding excessive bradycardia or hypotension. By carefully considering these factors and following established guidelines, healthcare providers can use PRN IV metoprolol effectively and safely to manage tachycardia in their patients.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Hold Parameters for PRN IV Metoprolol
The hold parameters for PRN (pro re nata) intravenous (IV) metoprolol for tachycardia are not explicitly stated in the provided studies. However, the studies provide information on the dosage and administration of metoprolol for various conditions.
Dosage and Administration
- The study by 2 administered metoprolol in one or two separate infusions of up to 7.5 mg each over a cumulative maximum interval of 25 minutes, with a mean dose of 9.5 mg.
- The study by 3 administered 0.1 mg/kg intravenous metoprolol, and also used oral metoprolol at a dose of 50-100 mg twice daily.
- The study by 4 delivered metoprolol boluses IP or IV, but does not specify the exact dosage.
Potential Side Effects
- The study by 2 reported hypotension as the most frequent side effect, occurring in five patients, but it was transient and readily managed.
- The study by 4 found that IV-administered metoprolol significantly lowered ventricular contractility and mean arterial pressure parameters, but these effects were nearly unaffected in IP-treated animals.
PRN Medication Use
- The study by 5 discusses the use of PRN medications in a psychiatric hospital, but does not provide specific information on the use of metoprolol as a PRN medication for tachycardia.