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Nirmatrelvir is a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) main protease (Mpro, also referred to as 3CLpro or nsp5 protease) inhibitor.
Ritonavir is an HIV-1 protease inhibitor but is not active against SARS-CoV-2 Mpro. Ritonavir inhibits the CYP3A-mediated metabolism of nirmatrelvir, resulting in increased plasma concentrations of nirmatrelvir.
For more information about how PAXLOVID works, see Section 12: Clinical Pharmacology in the Prescribing Information here.
The pharmacokinetics of nirmatrelvir/ritonavir have been studied in healthy subjects and in subjects with mild-to-moderate COVID-19.
Ritonavir is an HIV-1 protease inhibitor but is not active against SARS-CoV-2 Mpro. Ritonavir inhibits the CYP3A-mediated metabolism of nirmatrelvir, resulting in increased plasma concentrations of nirmatrelvir.
Nirmatrelvir AUC increased in a less than dose proportional manner over a single dose range from 250 mg to 750 mg (0.83 to 2.5 times the approved recommended dose) and multiple dose range from 75 mg to 500 mg (0.25 to 1.67 times the approved recommended dose) when administered in combination with 100 mg ritonavir. Nirmatrelvir steady state was achieved on Day 2 following administration of the approved recommended dosage and the mean accumulation ratio was approximately 2-fold.
For more information about the pharmacokinetics of PAXLOVID, see Section 12.3: Pharmacokinetics in the Prescribing Information here.
Consult the CDC for the latest information on risk factors: https://www.cdc.gov/coronavirus/2019-ncov/hcp/clinical-care/underlyingconditions.html.§
*Indicates presence of evidence for pregnant and non-pregnant people.
†Risk may be further increased for people receiving dialysis.
‡The language expressed on this page is consistent with CDC guidance, with the exception of risk factors regarding pediatric patients, which were removed from this list. PAXLOVID is not approved for use in pediatric patients.
§This link will take you to a website that is owned and operated by the CDC. Pfizer is not responsible for the content or services of this site.
With the PAXCESS™ Co-Pay Savings Program, eligible prescribed patients with commercial insurance may pay as little as $0* for their PAXLOVID prescription.
*Eligible commercially insured patients can save up to $1,500 per prescription. Maximum annual savings up to $1,500. Full terms and conditions apply. Please click here for full terms and conditions.
Patients enrolled in federal programs† such as Medicare, Medicaid,‡ and VA are not eligible for the Co-Pay Savings Program but may qualify for other financial assistance resources for PAXLOVID.
†The USG PAP operated by Pfizer will continue to provide patients on Medicare, Medicaid, TRICARE, Veteran Affairs Community Care Network, and those who are uninsured access to PAXLOVID for free through December 31, 2024. PAXLOVID, through the USG PAP, is not available to patients who have commercial prescription drug health insurance. The USG PAP operated by Pfizer is an independent program with separate eligibility requirements offered by the U.S. Department of Health and Human Services and is not owned by Pfizer.
‡Medicaid patients eligible through December 31, 2024.
Please visit the access page to learn more.
For more information on dosing adjustments, see Section 2.3: Dosage in Patients with Renal Impairment in the Full Prescribing Information here.
PAXLOVID consists of 2 medicines: nirmatrelvir and ritonavir. Nirmatrelvir must be coadministered with ritonavir. Failure to correctly coadminister nirmatrelvir with ritonavir may result in plasma levels of nirmatrelvir that are insufficient to achieve the desired therapeutic effect.
Patients should take 2 tablets of nirmatrelvir (150 mg each) with 1 tablet of ritonavir (100 mg) by mouth twice daily (in the morning and in the evening) for 5 days. For each dose, all 3 tablets should be taken at the same time.
To ensure appropriate dosing in patients with moderate renal impairment, reduce the dosage of PAXLOVID to 150 mg nirmatrelvir and 100 mg ritonavir twice daily for 5 days. Providers should counsel patients about renal dosing instructions.
For more information on how to take PAXLOVID, patients can refer to Patient Information here.
For medical questions related to PAXLOVID, you can visit pfizermedicalinformation.com or call Medical Information at 1-800-438-1985.
PAXLOVID (nirmatrelvir co-packaged with ritonavir) is a strong inhibitor of CYP3A, and an inhibitor of CYP2D6, P-gp, and OATP1B1. Co-administration of PAXLOVID with drugs that are primarily metabolized by CYP3A and CYP2D6 or are transported by P-gp or OATP1B1 may result in increased plasma concentrations of such drugs and increase the risk of adverse events. Co-administration of PAXLOVID with drugs highly dependent on CYP3A for clearance and for which elevated plasma concentrations are associated with serious and/or life‑threatening events is contraindicated. Co-administration with other CYP3A substrates may require a dose adjustment or additional monitoring as shown in Table 1.
Have a question about PAXLOVID? Request a visit from a product representative.
To report an adverse event, please call 1-800-438-1985
Pfizer for Professionals 1-800-505-4426
This site is intended only for U.S. healthcare professionals. The products discussed in this site may have different product labeling in different countries. The information provided is for educational purposes only.
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Drugs that are strong CYP3A inducers: PAXLOVID cannot be started immediately after discontinuation of any of the following medications due to the delayed offset of the recently discontinued CYP3A inducer:
Limitations of Use
PAXLOVID is not approved for use as pre-exposure or post-exposure prophylaxis for prevention of COVID-19.