What is the recommended administration protocol for Metoprolol (metoprolol) via IV stat or infusion?

Metoprolol IV Administration Protocol

For acute myocardial infarction, administer metoprolol as three 5 mg IV boluses at 2-minute intervals (total 15 mg), followed by oral metoprolol 50 mg every 6 hours starting 15 minutes after the last IV dose, but only if the patient has no signs of heart failure, low output state, systolic BP >120 mmHg, heart rate 60-110 bpm, and no contraindications to beta blockade. 1

IV Bolus Administration (Stat Dosing)

Standard Protocol for Acute MI

• Give 5 mg IV over 1-2 minutes 1, 2
• Repeat every 2-5 minutes as tolerated 1, 3
• Maximum total dose: 15 mg (three 5 mg boluses) 1, 2
• Monitor continuously during administration: blood pressure, heart rate, and ECG 1

Transition to Oral Therapy

• Start oral metoprolol 15 minutes after the last IV dose 1
• Initial oral dose: 50 mg every 6 hours for 48 hours in patients tolerating full IV dose 1
• Reduced oral dose: 25 mg every 6 hours in patients with partial intolerance 1
• Maintenance: 100 mg twice daily after initial 48 hours 1, 4

Absolute Contraindications (Do NOT Give IV Metoprolol)

IV metoprolol should not be administered if ANY of the following are present: 5, 2

• Signs of heart failure or decompensated HF 5, 2
• Evidence of low output state 5
• Systolic BP <120 mmHg 5, 2
• Heart rate >110 bpm or <60 bpm 5, 2
• PR interval >0.24 seconds 5, 2
• Second or third-degree heart block 5, 2
• Active asthma or reactive airway disease 5, 2
• Age >70 years with multiple risk factors (increased cardiogenic shock risk) 5
• Cardiogenic shock 2

IV Infusion Protocol (Alternative to Bolus)

For Supraventricular Tachycardia

• Esmolol infusion: 100-300 mcg/kg/min starting after surgery 5
• This approach allows for rapid titration and shorter duration of action 5

Perioperative Setting

• Esmolol 250 mg/h can be used intraoperatively, then transition to oral metoprolol 25-50 mg the following morning 5

Critical Monitoring During IV Administration

Perform the following checks during IV therapy: 2

• Continuous ECG monitoring 1
• Frequent blood pressure and heart rate checks (every 2-5 minutes during bolus administration) 1, 2
• Auscultate for rales (signs of pulmonary edema) 2
• Listen for bronchospasm 2
• Assess for symptomatic hypotension (dizziness, lightheadedness) 2

Evidence-Based Outcomes

Benefits of Early IV Metoprolol

• 36% mortality reduction in acute MI when given early (15 mg IV followed by oral therapy) 4
• Reduced reinfarction rate by 5 per 1000 patients treated 5
• Reduced ventricular fibrillation by 5 per 1000 patients 5
• Higher long-term LVEF (48.7% vs 45.0%) when given before reperfusion 6
• 68% reduction in heart failure admissions (HR 0.32) at 2-year follow-up 6

Risks of Early IV Metoprolol

• Increased cardiogenic shock by 11 per 1000 patients, particularly in first 24 hours 5
• 30% relative increase in cardiogenic shock overall 5
• Risk highest in patients >70 years, SBP <120 mmHg, HR >110 bpm, or Killip class >1 5

Common Pitfalls to Avoid

• Do not give IV metoprolol to patients with any signs of hemodynamic instability - the COMMIT trial showed increased cardiogenic shock in high-risk patients 5
• Do not assume all MI patients are candidates - carefully screen for contraindications before administration 5, 2
• Do not give IV metoprolol in pre-excitation with atrial fibrillation (can accelerate ventricular response) 2
• Do not administer if sepsis is suspected - beta-blockers mask compensatory tachycardia 2
• Do not use in alcohol withdrawal - can mask withdrawal symptoms 2

Special Populations

Hepatic Impairment

• Initiate at low doses with cautious gradual titration - metoprolol levels increase substantially in hepatic impairment 1

Geriatric Patients (>65 years)

• Use low initial starting dose given greater frequency of decreased organ function 1
• Higher risk of cardiogenic shock - age >70 is an independent risk factor 5

Renal Impairment

• No dose adjustment required 1