What is the recommended dosing for patients taking Celexa (citalopram) and Wellbutrin (bupropion) for depression, and Metoprolol (metoprolol tartrate) for hypertension or heart conditions?

Dosing Recommendations for Citalopram, Bupropion, and Metoprolol

When prescribing citalopram (Celexa), bupropion (Wellbutrin), and metoprolol tartrate for patients with depression and hypertension or heart conditions, bupropion should be avoided due to significant drug interactions with metoprolol that can cause severe bradycardia and atrioventricular block.

Citalopram (Celexa) Dosing

• Initial dose: 10 mg daily 1
• Maximum dose: 40 mg daily 1
• Well tolerated but may cause nausea and sleep disturbances 1
• Recent evidence suggests citalopram may actually help lower blood pressure in hypertensive patients with depression 2

Bupropion (Wellbutrin) Considerations

• NOT recommended for concurrent use with metoprolol due to potent CYP2D6 inhibition that increases metoprolol levels 4-6 fold 3
• If bupropion must be used (which is not recommended):
  • Initial dose: 37.5 mg every morning, then increase by 37.5 mg every 3 days 1
  • Maximum dose: 150 mg twice daily 1
  • Should not be used in agitated patients or those with seizure disorders 1
  • Second dose should be given before 3 p.m. to minimize insomnia risk 1

Metoprolol Tartrate Dosing

• For hypertension: 25-100 mg twice daily 4
• For heart failure: Start at 6.25-12.5 mg twice daily, target 50 mg twice daily 4
• Note: 100 mg twice daily of metoprolol tartrate is equivalent to 200 mg once daily of metoprolol succinate 4, 5

Important Drug Interaction Warnings

1. Metoprolol and Bupropion:

   • Severe interaction - bupropion potently inhibits CYP2D6, increasing metoprolol levels 4-6 fold 3
   • Can cause severe bradycardia and atrioventricular block 3
   • This combination should be avoided 3

2. Metoprolol and Citalopram:

   • Moderate interaction - citalopram is a less potent CYP2D6 inhibitor
   • Can cause 2-3 fold increases in metoprolol levels 3
   • Consider reducing metoprolol dose when used with citalopram 3

Alternative Recommendations

If all three medications are deemed necessary:

1. Consider switching from metoprolol tartrate to a beta-blocker less affected by CYP2D6 inhibition
2. Consider switching from bupropion to another antidepressant with minimal CYP2D6 inhibition:
   • Sertraline (Zoloft): 25-50 mg per day initially, maximum 200 mg per day 1
   • Mirtazapine (Remeron): 7.5 mg at bedtime initially, maximum 30 mg at bedtime 1
   • These antidepressants inhibit CYP2D6 to little or no extent and are not expected to cause clinically relevant interactions with metoprolol 3

Monitoring Recommendations

• Monitor heart rate and blood pressure closely, especially during initiation and dose adjustments 4
• Watch for signs of excessive beta-blockade (bradycardia, hypotension, dizziness)
• If bradycardia or hypotension occurs, reduce metoprolol dose or consider alternative medications

Special Populations

• Women may require lower metoprolol doses due to higher exposure from reduced metabolism 4
• Elderly patients should start with lower doses of all medications and titrate slowly 4
• Patients with heart failure should follow heart failure-specific dosing for metoprolol 4

Remember that the combination of metoprolol and bupropion poses significant risks and should be avoided whenever possible due to the potential for serious cardiovascular adverse effects.