From the Guidelines
The recommended dosage for Paxlovid (nirmatrelvir/ritonavir) is 300 mg/100 mg orally every 12 hours for five days, as early as possible in the course of the disease. This dosage is based on the most recent and highest quality study available, which recommends this regimen for maximum effectiveness in treating COVID-19 1.
Key Considerations
- The medication should be taken as soon as possible after diagnosis of COVID-19 and within 5 days of symptom onset.
- For patients with moderate renal impairment (eGFR 30-59 mL/min), a dose reduction to 150 mg/100 mg orally every 12 hours for five days may be warranted 1.
- Clinicians should use nirmatrelvir/ritonavir with caution in patients with severe kidney impairment and severe liver impairment, as trials excluded these patients and ritonavir can perpetrate many drug-drug interactions 1.
Administration
- Paxlovid should be administered orally, with or without food.
- The tablets should be swallowed whole and not chewed, broken, or crushed.
Mechanism of Action
- Nirmatrelvir works by inhibiting a key enzyme (3CL protease) that the SARS-CoV-2 virus needs for replication.
- Ritonavir slows the breakdown of nirmatrelvir, maintaining effective concentrations in the body to fight the infection.
From the FDA Drug Label
2.2 Recommended Dosage The recommended dosage for PAXLOVID is 300 mg nirmatrelvir (two 150 mg tablets) with 100 mg ritonavir (one 100 mg tablet) with all 3 tablets taken together orally twice daily in the morning and at bedtime for 5 days.
The recommended dosage for Paxlovid (nirmatrelvir/ritonavir) is:
- 300 mg nirmatrelvir (two 150 mg tablets)
- 100 mg ritonavir (one 100 mg tablet) taken together orally twice daily in the morning and at bedtime for 5 days 2.
Key considerations:
- The dosage may need to be adjusted in patients with renal impairment.
- No dosage adjustment is recommended in patients with mild renal impairment.
- The dosage should be reduced in patients with moderate or severe renal impairment.
- Patients with severe hepatic impairment should not use Paxlovid.
From the Research
Dosage Information for Paxlovid (Nirmatrelvir/Ritonavir)
The recommended dosage for Paxlovid, which is a combination of nirmatrelvir and ritonavir, is not explicitly stated in the provided studies. However, the following information can be gathered:
- Paxlovid is administered as a 5-day course oral treatment 3.
- The treatment is given every 12 hours for 5 days 4.
- There is no specific information on the dosage amount (e.g., milligrams) provided in the studies.
Considerations for Special Populations
Some studies discuss the use of Paxlovid in special populations, such as:
- Patients with advanced kidney disease: Nirmatrelvir-ritonavir is used in patients with normal or mild renal impairment (eGFR ≥30 ml/min per 1.73 m2), but there is limited data regarding its use in advanced kidney disease (eGFR <30 ml/min per 1.73 m2) 5.
- Geriatric subjects: Simulations were performed to evaluate the drug-drug interactions of ritonavir with anticoagulants in geriatric subjects 6.
Drug-Drug Interactions
Paxlovid has a high potential to cause harm from drug-drug interactions (DDIs) due to the ritonavir component, which inhibits the cytochrome P450 (CYP) 3A4 enzyme 3, 7.
- Options for mitigating risk from DDIs with nirmatrelvir/ritonavir are limited and largely confined to preemptive or symptom-driven pausing of the comedication or managing any additional risk through counseling 3.
- Physiologically-based pharmacokinetic (PBPK) modeling can be used to simulate the complex DDIs of ritonavir with other drugs, such as anticoagulants 6.