Can a 77-year-old male with CKD (Chronic Kidney Disease), HTN (Hypertension), and on multiple medications including a statin, be treated with Paxlovid (nirmatrelvir/ritonavir)?

Paxlovid Treatment for 77-Year-Old Male with CKD, HTN, and COVID-19 Exposure

Paxlovid (nirmatrelvir/ritonavir) can be prescribed for this patient with CKD, but requires dose adjustment to 150/100 mg twice daily for 5 days due to his moderate renal impairment (eGFR 40 ml/min/1.73m²), and several medication interactions must be managed before initiation.

Renal Considerations and Dosing

• Nirmatrelvir is primarily eliminated by the kidneys, requiring dose adjustment in patients with renal impairment 1
• For patients with moderate renal impairment (eGFR 30-60 ml/min/1.73m²), the recommended dose is reduced to 150/100 mg nirmatrelvir/ritonavir twice daily for 5 days 1
• The patient's eGFR of 40 ml/min/1.73m² places him in the moderate renal impairment category, making him eligible for Paxlovid with appropriate dose adjustment

Drug-Drug Interactions Assessment

The ritonavir component of Paxlovid is a potent inhibitor of CYP3A4 enzymes and P-glycoprotein transporters, creating significant potential for drug interactions 2. Several of the patient's medications require attention:

Critical Interactions Requiring Management:

1. Statin: Must be temporarily held during Paxlovid treatment due to risk of myopathy and rhabdomyolysis from CYP3A4 inhibition 2

2. Fenofibrate: Should be temporarily discontinued during treatment due to increased risk of adverse effects when combined with ritonavir 3

3. Allopurinol: Can be continued as it does not have significant interactions with Paxlovid 4

   • Note: The KDIGO guidelines recommend allopurinol for symptomatic hyperuricemia in CKD patients 4

4. Ramipril (ACE inhibitor): Can be continued but monitor closely for hypotension and renal function changes 3

5. Metoprolol: May have increased plasma concentrations due to CYP2D6 inhibition by ritonavir; consider reducing dose by 50% during Paxlovid treatment and monitor for bradycardia 3

6. Doxazosin: May have increased plasma concentrations; consider reducing dose by 50% during Paxlovid treatment and monitor for hypotension 3

Colchicine Warning

• If the patient is also taking colchicine for gout management, this must be discontinued during Paxlovid treatment
• KDIGO guidelines specifically warn against concomitant use of colchicine with ritonavir/nirmatrelvir due to risk of severe colchicine toxicity 4

Monitoring Recommendations

• Check baseline renal function and electrolytes before starting treatment
• Monitor for hypotension due to potential additive effects with antihypertensive medications
• Assess for drug-related adverse effects during treatment, particularly cardiovascular symptoms
• Resume regular medications 2-3 days after completing the 5-day course of Paxlovid

Benefits vs. Risks

• Benefits: Paxlovid significantly reduces risk of hospitalization and death in high-risk COVID-19 patients
• The patient's age (77) and comorbidities (CKD, HTN) place him at high risk for severe COVID-19, making him an appropriate candidate for treatment
• A modified dose regimen has been shown to be safe and well-tolerated in patients with renal impairment 5

Implementation Plan

1. Hold statin and fenofibrate during treatment and for 2-3 days after
2. Reduce metoprolol and doxazosin doses by 50% during treatment
3. Continue ramipril and allopurinol with monitoring
4. Prescribe nirmatrelvir/ritonavir 150/100 mg twice daily for 5 days
5. Schedule follow-up within one week to reassess symptoms and medication management

This approach balances the benefits of Paxlovid treatment against the risks of drug interactions while accounting for the patient's renal function.