What is the maximum daily dose of intravenous (IV) metoprolol?

Maximum Daily Dose of IV Metoprolol

The maximum daily dose of intravenous (IV) metoprolol is 15 mg, administered as three bolus injections of 5 mg each at approximately 2-minute intervals. This dosing is based on the FDA-approved labeling and clinical guidelines for the management of patients with acute cardiac conditions 1.

Dosing Protocol for IV Metoprolol

Standard Administration

• Initial dose: Three bolus injections of 5 mg each
• Administration rate: Each 5 mg dose given over 1-2 minutes
• Interval between doses: Approximately 2 minutes
• Maximum total IV dose: 15 mg

Monitoring Requirements

During IV metoprolol administration, the following should be monitored:

• Blood pressure
• Heart rate
• Continuous ECG monitoring
• Signs of heart failure or bronchospasm

Transition to Oral Therapy

After completing IV administration, patients who tolerate the full 15 mg dose should transition to oral therapy:

• Begin oral metoprolol tartrate 50 mg every 6 hours, 15 minutes after the last IV dose
• Continue this regimen for 48 hours
• Then transition to maintenance dose of 100 mg orally twice daily 1, 2

For patients who cannot tolerate the full IV dose:

• Start with lower oral doses (25-50 mg every 6 hours) depending on the degree of intolerance
• Begin 15 minutes after the last IV dose or when clinically stable

Contraindications and Cautions

IV metoprolol should not be administered to patients with:

• Signs of heart failure
• Evidence of a low output state
• Increased risk for cardiogenic shock
• PR interval >0.24 seconds
• Second or third-degree heart block
• Active asthma or reactive airway disease 2

Risk Factors for Cardiogenic Shock

• Age >70 years
• Systolic BP <120 mmHg
• Heart rate >110 bpm or <60 bpm
• Increased time since symptom onset 2

Special Populations

Hepatic Impairment

• Blood levels likely to increase substantially
• Initiate at lower doses with cautious titration

Elderly Patients

• Use lower initial doses
• Consider decreased hepatic, renal, or cardiac function
• Account for concomitant diseases or medications 1

Clinical Pearls

• The 15 mg maximum IV dose is significantly lower than the maximum daily oral dose (400 mg)
• IV metoprolol should be administered in a setting with intensive monitoring
• The COMMIT trial showed that excessive IV beta-blockade can increase the risk of cardiogenic shock, particularly in high-risk patients 2
• Always inspect parenteral solutions for particulate matter and discoloration prior to administration 1

Remember that while the maximum single IV administration is 15 mg total, this should not be repeated within the same day, as patients are typically transitioned to oral therapy after the initial IV loading dose.