Can I take Paxlovid (nirmatrelvir and ritonavir) with cefuroxime?

Paxlovid and Cefuroxime Interaction

Paxlovid (nirmatrelvir/ritonavir) should not be co-administered with cefuroxime due to the risk of serious drug interactions caused by ritonavir's strong inhibition of CYP3A4 enzymes.

Mechanism of Interaction

Ritonavir, a component of Paxlovid, is a potent inhibitor of CYP3A4 enzymes and P-glycoprotein (P-gp) transporters. According to the KDOQI US Commentary on the KDIGO 2024 Clinical Practice Guideline, ritonavir/nirmatrelvir (Paxlovid) should not be used concomitantly with medications metabolized by CYP3A4, which includes certain macrolide antibiotics 1.

While cefuroxime itself is not primarily metabolized by CYP3A4 (it's a cephalosporin antibiotic), the concern stems from:

1. The potential for altered pharmacokinetics when combined with a strong CYP inhibitor like ritonavir
2. The risk of additive adverse effects
3. The potential for decreased efficacy of one or both medications

Clinical Implications

The co-administration of these medications may lead to:

• Altered plasma concentrations of either medication
• Increased risk of adverse effects
• Potential treatment failure for either COVID-19 or the bacterial infection being treated with cefuroxime

Alternative Approaches

If you need treatment for COVID-19 and have a bacterial infection requiring antibiotic therapy, consider these options:

1. Consult with a clinical pharmacist or infectious disease specialist to evaluate the specific interaction risk in your case
2. Consider alternative COVID-19 treatments if you must continue cefuroxime
3. Evaluate if a different antibiotic with fewer interaction concerns could be used instead of cefuroxime

Special Considerations

Renal Function

• For patients with moderate renal impairment (eGFR 30-59 mL/min), Paxlovid dosing should be adjusted to nirmatrelvir 150 mg/ritonavir 100 mg twice daily 2
• Both medications may require dose adjustments in renal impairment

Monitoring

If co-administration cannot be avoided:

• Monitor for signs of toxicity or treatment failure
• Consider therapeutic drug monitoring if available
• Watch for adverse effects from either medication

Conclusion

The safest approach is to avoid co-administration of Paxlovid and cefuroxime. If treatment for both conditions is necessary, consult with specialists to determine the safest and most effective treatment strategy based on your specific clinical situation.