Recommended Treatment Timeline for COVID-19 with Paxlovid
Paxlovid (nirmatrelvir/ritonavir) should be initiated as soon as possible after COVID-19 diagnosis and within 5 days of symptom onset for optimal effectiveness. 1, 2
Dosing and Administration Timeline
- Paxlovid should be administered as 300 mg nirmatrelvir (two 150 mg tablets) with 100 mg ritonavir (one 100 mg tablet), with all three tablets taken together twice daily for 5 days 1, 2
- Treatment should be started as early as possible in the disease course, ideally within the first 5 days of symptom onset 1, 3
- Administer orally with or without food at approximately the same time each day 2
Dose Adjustments for Special Populations
- For patients with moderate renal impairment (eGFR ≥30 to <60 mL/min): 150 mg nirmatrelvir with 100 mg ritonavir twice daily for 5 days 2
- For patients with severe renal impairment (eGFR <30 mL/min): 300 mg nirmatrelvir with 100 mg ritonavir once on day 1, followed by 150 mg nirmatrelvir with 100 mg ritonavir once daily for days 2-5 2
- Not recommended for patients with severe hepatic impairment (Child-Pugh Class C) 2
Patient Selection and Timing
- Strongly recommended for patients with non-severe COVID-19 at high risk of hospitalization 1
- Conditionally recommended for patients with moderate risk of hospitalization 1
- Not recommended for patients at low risk of hospitalization 1
- Clinical trials demonstrated an 89% reduction in risk of progression to severe COVID-19 when started within 3-5 days of symptom onset 3
- Real-world data shows approximately 39% reduction in hospitalization risk and 61% reduction in mortality 4
Drug Interaction Considerations
- Ritonavir is a strong CYP3A inhibitor that causes many drug-drug interactions 5, 2
- Prior to prescribing:
- Drug interactions may persist for several days after completing the 5-day treatment course due to ritonavir's effects on metabolism 1, 5
- Use of the Liverpool COVID-19 Drug Interaction Tool is recommended to check for specific interactions 5
Monitoring and Follow-up
- Monitor patients for common adverse effects including dysgeusia (altered taste) and diarrhea 1, 3
- Serious adverse events are rare but include potential hepatotoxicity 5
- No specific post-treatment monitoring is required in most patients, but those with drug interactions may need monitoring beyond the 5-day treatment period 1
Common Pitfalls and Caveats
- Delaying treatment beyond 5 days of symptom onset significantly reduces effectiveness 3
- Failing to check for drug-drug interactions before prescribing can lead to serious adverse events 5, 2
- Not adjusting dosage for patients with renal impairment can lead to overexposure and increased adverse effects 2
- Paxlovid is not approved for use as pre-exposure or post-exposure prophylaxis for prevention of COVID-19 2
- Drug interactions with certain medications (e.g., amiodarone, rivaroxaban, simvastatin) may be contraindicated or require temporary discontinuation of these medications 5