What is the oral dosage of metoprolol for a patient with tachycardia and no IV access?

Management of Tachycardia (HR 150 bpm) with Oral Metoprolol

For a patient with tachycardia (HR 150 bpm) and no IV access, metoprolol tartrate 25-50 mg orally should be administered immediately, with the option to repeat in 6-12 hours as needed based on heart rate response. 1

Initial Dosing Considerations

• Metoprolol tartrate is preferred over succinate for acute tachycardia management due to its faster onset of action 1
• Initial oral dosing should be 25-50 mg of metoprolol tartrate, which can be repeated every 6-12 hours as needed 1
• Oral metoprolol has demonstrated effectiveness in controlling heart rate within 1-3 hours in tachycardic patients 2, 3
• For patients with severe tachycardia (HR 150 bpm), starting with 50 mg is reasonable if no contraindications exist 1

Monitoring and Follow-up

• After administration, monitor heart rate, blood pressure, and respiratory status every 15-30 minutes until stabilized 1
• Target heart rate should be <100 bpm initially, with a goal of 60-100 bpm once stabilized 1
• If inadequate response after 1 hour, consider administering an additional 25 mg dose (not exceeding 100 mg total in first 6 hours) 1
• Once rate is controlled, transition to a maintenance regimen of 25-100 mg twice daily of metoprolol tartrate 1

Contraindications and Cautions

• Avoid metoprolol in patients with signs of heart failure, low cardiac output, increased risk of cardiogenic shock, PR interval >0.24 seconds, second or third-degree heart block, active asthma, or reactive airways disease 1
• Risk factors for cardiogenic shock include age >70 years, systolic BP <120 mm Hg, tachycardia >110 bpm or bradycardia <60 bpm 1
• Use with caution in patients with decompensated heart failure or pre-excited atrial fibrillation/flutter 1
• If the patient has known or suspected pre-excitation syndrome (WPW), beta-blockers should be avoided 1

Alternative Approaches

• If metoprolol is contraindicated or ineffective, consider:
  • Non-dihydropyridine calcium channel blockers (diltiazem or verapamil) orally if no heart failure is present 1
  • Digoxin 0.25 mg orally if heart failure is present 1
  • Amiodarone 200 mg orally if other options are contraindicated 1

Special Considerations

• Studies have shown that oral metoprolol can effectively convert multifocal atrial tachycardia to sinus rhythm in 68% of patients, often within 5 hours 3
• In supraventricular tachycardias, metoprolol has demonstrated effectiveness in both rate control and conversion to sinus rhythm 4, 5
• For patients with atrial fibrillation, a heart rate control strategy (resting heart rate <80 bpm) is reasonable for symptomatic management 1

Remember that the specific clinical context (type of tachycardia, underlying cause, comorbidities) should guide treatment decisions, but immediate oral metoprolol administration is appropriate for most cases of tachycardia when IV access is unavailable.