What is the proper way to order Paxlovid (nirmatrelvir and ritonavir)?

How to Order Paxlovid (Nirmatrelvir/Ritonavir)

To properly order Paxlovid, prescribe nirmatrelvir 300 mg (two 150 mg tablets) with ritonavir 100 mg (one 100 mg tablet) to be taken together orally twice daily for 5 days, initiated within 5 days of COVID-19 symptom onset. 1, 2

Patient Selection and Timing

1. Identify eligible patients:

   • High-risk adults with mild-to-moderate COVID-19
   • Treatment must begin within 5 days of symptom onset
   • Prioritize patients at high risk for hospitalization or death 1

2. Assess renal function:

   • Normal to mild impairment (eGFR ≥60 mL/min): Standard dose
   • Moderate impairment (eGFR 30-59 mL/min): Reduced dose of 150 mg nirmatrelvir with 100 mg ritonavir twice daily
   • Severe impairment (eGFR <30 mL/min): Day 1: 300 mg nirmatrelvir with 100 mg ritonavir once; Days 2-5: 150 mg nirmatrelvir with 100 mg ritonavir once daily 1, 2, 3

3. Assess hepatic function:

   • Not recommended in patients with severe hepatic impairment (Child-Pugh Class C) 2

Critical Step: Drug Interaction Screening

This is the most important safety consideration when ordering Paxlovid:

1. Review ALL medications the patient is currently taking
2. Check for contraindicated medications that interact with ritonavir (strong CYP3A inhibitor)
3. Use the Liverpool COVID-19 Drug Interaction Tool to identify and manage potential interactions 1
4. Common problematic medications include:
   • Anticoagulants (particularly rivaroxaban) 4
   • Certain statins, antiarrhythmics, and sedatives
   • Medications highly dependent on CYP3A for clearance 2

Prescription Details

1. Standard dosing:

   • Nirmatrelvir 300 mg (two 150 mg tablets) with ritonavir 100 mg (one 100 mg tablet)
   • Take all three tablets together twice daily for 5 days
   • Can be taken with or without food 2

2. Administration instructions:

   • Take at approximately the same time each day
   • Swallow tablets whole (do not chew, break, or crush)
   • Complete the full 5-day course 1, 2

Patient Education

When ordering Paxlovid, ensure patients understand:

1. The importance of starting treatment within 5 days of symptom onset
2. The need to complete the full 5-day course
3. Common side effects: dysgeusia (altered taste) and diarrhea 5
4. The critical importance of disclosing all medications they are taking
5. To report any serious side effects immediately

Common Pitfalls to Avoid

• Failure to screen for drug interactions - this is the most common and potentially dangerous error
• Not adjusting dosage for renal impairment
• Prescribing beyond 5 days from symptom onset
• Not completing the full treatment course
• Not specifying the numeric dose of each active ingredient 2

Special Considerations

• Pregnancy: Paxlovid represents an option for pregnant people with COVID-19 to reduce disease progression risk 1
• Hemodialysis patients: Administer dose after hemodialysis 2
• Drug interactions: May require dose adjustments, temporary discontinuation, or additional monitoring of concomitant medications 1, 2

Remember that Paxlovid has demonstrated an 89% relative risk reduction in hospitalization and death when given within 3 days of symptom onset in high-risk, unvaccinated adults 5, making proper and timely prescribing crucial for optimal patient outcomes.