Metoprolol Tartrate (Toprol) to IV Metoprolol Conversion
When converting from oral metoprolol tartrate (Toprol) to IV metoprolol, use a ratio of 1:1 with 50 mg oral metoprolol tartrate equivalent to 5 mg IV metoprolol given as bolus doses. 1
Conversion Guidelines
The conversion from oral to IV metoprolol follows these principles:
- Oral to IV ratio: 10:1 (50 mg oral = 5 mg IV)
- Standard IV dosing: 2.5-5.0 mg IV bolus over 2 minutes
- Maximum IV dosing: Can repeat 2.5-5.0 mg IV bolus in 10 minutes, up to 3 doses (maximum 15 mg) 1
Specific Conversion Table
| Oral Metoprolol Tartrate | IV Metoprolol Equivalent |
|---|---|
| 25 mg | 2.5 mg |
| 50 mg | 5 mg |
| 100 mg | 10 mg |
| 200 mg | 15 mg (maximum recommended) |
Administration Protocol
For acute situations requiring IV metoprolol:
- Initial dose: 5 mg IV bolus over 2 minutes
- Monitoring: Observe blood pressure, heart rate, and ECG during administration
- Subsequent dosing: Can repeat 5 mg IV bolus at 10-minute intervals if needed
- Maximum total dose: 15 mg (three 5 mg boluses) 1, 2
Clinical Considerations
- Heart rate control: IV metoprolol achieves more rapid beta-blockade than oral formulations
- Monitoring: Continuous cardiac monitoring is essential during IV administration
- Transition back to oral: After IV administration, transition to oral metoprolol tartrate 50 mg every 6 hours, 15 minutes after the last IV dose 2
Precautions
- Contraindications: Avoid in cardiogenic shock, decompensated heart failure, significant bradycardia, or heart block greater than first degree 1
- Hypotension risk: IV administration carries higher risk of hypotension compared to oral dosing
- Hepatic impairment: Reduce dose in patients with hepatic dysfunction as metoprolol blood levels may increase substantially 2
- Monitoring: Continuous cardiac monitoring is required during IV administration
Special Populations
- Elderly patients: Start with lower doses (2.5 mg IV) due to increased risk of adverse effects
- Acute MI: Standard protocol is three 5 mg IV boluses at 2-minute intervals, followed by oral therapy 2
Remember that IV metoprolol has a much more rapid onset of action and potentially more pronounced hemodynamic effects than oral formulations, requiring close monitoring during administration.