Is it safe to take Plaquenil (hydroxychloroquine) and metoprolol together?

Safety of Taking Plaquenil (Hydroxychloroquine) and Metoprolol Together

It is generally safe to take Plaquenil (hydroxychloroquine) and metoprolol together, but this combination requires monitoring for potential QT interval prolongation and hemodynamic effects. 1, 2

Drug Interaction Analysis

Pharmacokinetic Interactions

• Hydroxychloroquine is a weak inhibitor of CYP2D6 1
• Metoprolol is primarily metabolized by CYP2D6 2
• This interaction may lead to increased metoprolol plasma levels, but the effect is relatively mild compared to strong CYP2D6 inhibitors

Pharmacodynamic Interactions

• Both medications have potential cardiac effects:
  • Hydroxychloroquine can prolong QT interval 1
  • Metoprolol can cause bradycardia and hypotension 1
  • Combined use may theoretically increase risk of cardiac adverse effects

Monitoring Recommendations

When taking hydroxychloroquine and metoprolol together:

1. Cardiac Monitoring:

   • ECG monitoring recommended at baseline and periodically during treatment
   • Monitor for symptoms of bradycardia (dizziness, fatigue, syncope)
   • Watch for signs of QT prolongation (palpitations, lightheadedness)

2. Blood Pressure Monitoring:

   • Regular blood pressure checks
   • Be alert for orthostatic hypotension, especially when starting therapy

3. Dose Considerations:

   • Consider starting with lower doses of metoprolol if initiating both medications simultaneously
   • Dose adjustments may be needed based on clinical response

Risk Factors Requiring Extra Caution

The combination requires additional monitoring in patients with:

• Pre-existing cardiac conditions (heart block, sinus node dysfunction)
• Electrolyte abnormalities (especially hypokalemia or hypomagnesemia)
• Renal impairment
• Concomitant use of other QT-prolonging medications
• Elderly patients (≥75 years) 1

Common Pitfalls to Avoid

1. Medication Interactions: Avoid adding other strong CYP2D6 inhibitors (fluoxetine, paroxetine, bupropion) which could dramatically increase metoprolol levels 3, 4

2. Overlooking Symptoms: Don't dismiss new-onset dizziness, fatigue, or syncope as these may indicate excessive beta-blockade

3. Abrupt Discontinuation: Never stop metoprolol suddenly as this can lead to rebound hypertension or tachycardia 1

4. Electrolyte Imbalances: Maintain normal potassium and magnesium levels to reduce risk of QT prolongation with hydroxychloroquine

Conclusion

While hydroxychloroquine and metoprolol can be used together, appropriate monitoring should be implemented, particularly for cardiac effects. The interaction is not listed as a major contraindication in current guidelines, but awareness of the potential for increased metoprolol effects and QT interval changes is important for safe medication management.