Conversion from Lopressor (Metoprolol Tartrate) to Coreg (Carvedilol)
When converting from Lopressor (metoprolol tartrate) to Coreg (carvedilol), the equivalent dose ratio is approximately 4:1, meaning 100 mg of metoprolol tartrate is equivalent to approximately 25 mg of carvedilol.
Conversion Guidelines
The 2022 AHA/ACC/HFSA Heart Failure Guidelines provide the following target doses for these beta-blockers 1:
| Beta-Blocker | Initial Daily Dose | Target Dose | Mean Dose in Clinical Trials |
|---|---|---|---|
| Metoprolol tartrate | 25-100 mg BID | 100 mg BID | N/A |
| Metoprolol succinate | 12.5-25 mg once daily | 200 mg once daily | 159 mg total daily |
| Carvedilol | 3.125 mg twice daily | 25-50 mg twice daily | 37 mg total daily |
| Carvedilol CR | 10 mg once daily | 80 mg once daily | N/A |
Conversion Algorithm
- Calculate total daily metoprolol tartrate dose
- Divide by 4 to get total daily carvedilol dose
- Divide carvedilol dose by 2 for twice-daily dosing
Examples:
- Metoprolol tartrate 50 mg BID (100 mg/day) → Carvedilol 12.5 mg BID (25 mg/day)
- Metoprolol tartrate 100 mg BID (200 mg/day) → Carvedilol 25 mg BID (50 mg/day)
Important Clinical Considerations
Pharmacological Differences
- Metoprolol is a selective β1-receptor blocker at lower doses but becomes less selective at higher doses 2
- Carvedilol is a non-selective β1, β2, and α1-receptor blocker at all clinically relevant doses 2
- Carvedilol has additional vasodilatory and antioxidant properties not present in metoprolol
Clinical Outcomes
- The COMET trial demonstrated that carvedilol extended survival compared to metoprolol tartrate in heart failure patients (34% vs 40% all-cause mortality) 3
- Carvedilol has more favorable metabolic effects in patients with diabetes and hypertension, with less impact on glycemic control compared to metoprolol 4
Practical Considerations
- Start with a low dose of carvedilol (3.125 mg BID) when switching from metoprolol
- Titrate gradually every 1-2 weeks based on blood pressure, heart rate, and symptoms 1
- Monitor for orthostatic hypotension due to carvedilol's alpha-blocking effects
- Consider patient's comorbidities (diabetes, COPD, etc.) when selecting beta-blocker
Titration Schedule
- Start with carvedilol 3.125 mg BID regardless of previous metoprolol dose
- If tolerated after 1-2 weeks, increase to 6.25 mg BID
- Continue doubling the dose every 1-2 weeks as tolerated
- Target dose is 25 mg BID for most patients (50 mg BID for patients >85 kg)
Cautions and Contraindications
Both medications are contraindicated in:
- Severe bradycardia
- High-grade AV block without pacemaker
- Cardiogenic shock
- Decompensated heart failure 1
Extended-Release Considerations
If switching from metoprolol tartrate to carvedilol CR (controlled-release):
- Carvedilol CR allows once-daily dosing with equivalent efficacy to twice-daily immediate-release formulation 5
- Use a 2:1 conversion ratio from total daily carvedilol IR dose to CR dose
Remember that the goal of beta-blocker therapy is to achieve the target doses shown to be efficacious in clinical trials, as this has been demonstrated to reduce cardiovascular mortality and heart failure hospitalizations 1.