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Nirmatrelvir And Ritonavir

FDA Drug Information • Also known as: Paxlovid

Brand Names
Paxlovid
Dosage Form
KIT
Product Type
HUMAN PRESCRIPTION DRUG

⚠ Boxed Warning (Black Box)

WARNING: SIGNIFICANT DRUG INTERACTIONS WITH PAXLOVID

  • PAXLOVID includes ritonavir, a strong CYP3A inhibitor, which may lead to greater exposure of certain concomitant medications, resulting in potentially severe, life-threatening, or fatal events [see Contraindications (4) , Warnings and Precautions (5.1) , and Drug Interactions (7) ].
  • Prior to prescribing PAXLOVID: 1) Review all medications taken by the patient to assess potential drug-drug interactions with a strong CYP3A inhibitor like PAXLOVID and 2) Determine if concomitant medications require a dose adjustment, interruption, and/or additional monitoring [see Drug Interactions (7) ].
  • Consider the benefit of PAXLOVID treatment in reducing hospitalization and death, and whether the risk of potential drug-drug interactions for an individual patient can be appropriately managed [see Warnings and Precautions (5.1) , Drug Interactions (7) , and Clinical Studies (14) ]. WARNING: SIGNIFICANT DRUG INTERACTIONS WITH PAXLOVID See full prescribing information for complete boxed warning.
  • PAXLOVID includes ritonavir, a strong CYP3A inhibitor, which may lead to greater exposure of certain concomitant medications, resulting in potentially severe, life-threatening, or fatal events. ( 4 , 5.1 , 7 )
  • Prior to prescribing PAXLOVID: 1) Review all medications taken by the patient to assess potential drug-drug interactions with a strong CYP3A inhibitor like PAXLOVID and 2) Determine if concomitant medications require a dose adjustment, interruption, and/or additional monitoring. ( 7 )
  • Consider the benefit of PAXLOVID treatment in reducing hospitalization and death, and whether the risk of potential drug-drug interactions for an individual patient can be appropriately managed. ( 5.1 , 7 , 14 )

    • Description

    11 DESCRIPTION PAXLOVID is nirmatrelvir tablets co-packaged with ritonavir tablets. Nirmatrelvir is a SARS-CoV-2 main protease (M pro ) inhibitor, and ritonavir is an HIV-1 protease inhibitor and CYP3A inhibitor. Nirmatrelvir The chemical name of active ingredient of nirmatrelvir is (1 R ,2 S ,5 S )- N -((1 S )-1-Cyano-2-((3 S )-2-oxopyrrolidin-3-yl)ethyl)-3-((2 S )-3,3-dimethyl-2-(2,2,2-trifluoroacetamido)butanoyl)-6,6-dimethyl-3-azabicyclo[3.1.0]hexane-2-carboxamide]. It has a molecular formula of C 23 H 32 F 3 N 5 O 4 and a molecular weight of 499.54. Nirmatrelvir has the following structural formula: Nirmatrelvir is available as immediate-release, film-coated tablets. Each tablet contains 150 mg nirmatrelvir with the following inactive ingredients: colloidal silicon dioxide, croscarmellose sodium, lactose monohydrate, microcrystalline cellulose, and sodium stearyl fumarate. The following are the ingredients in the film coating: hydroxy propyl methylcellulose, iron oxide red, polyethylene glycol, and titanium dioxide. Chemical Structure Ritonavir Ritonavir is chemically designated as 10-Hydroxy-2-methyl-5-(1-methylethyl)-1- [2-(1 methylethyl)-4-thiazolyl]-3,6-dioxo-8,11-bis(phenylmethyl)-2,4,7,12- tetraazatridecan-13-oic acid, 5-thiazolylmethyl ester, [5S-(5R*,8R*,10R*,11R*)]. Its molecular formula is C 37 H 48 N 6 O 5 S 2 , and its molecular weight is 720.95. Ritonavir has the following structural formula: Ritonavir is available as film-coated tablets. Each tablet contains 100 mg ritonavir with the following inactive ingredients: anhydrous dibasic calcium phosphate, colloidal silicon dioxide, copovidone, sodium stearyl fumarate, and sorbitan monolaurate. The film coating may include the following ingredients: colloidal anhydrous silica, colloidal silicon dioxide, hydroxypropyl cellulose, hypromellose, polyethylene glycol, polysorbate 80, talc, and titanium dioxide. Chemical Structure

    What Is Nirmatrelvir And Ritonavir Used For?

    1 INDICATIONS AND USAGE PAXLOVID is indicated for the treatment of mild-to-moderate coronavirus disease 2019 (COVID-19) in adults who are at high risk for progression to severe COVID-19, including hospitalization or death. PAXLOVID which includes nirmatrelvir, a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) main protease (M pro : also referred to as 3CL pro or nsp5 protease) inhibitor, and ritonavir, an HIV-1 protease inhibitor and CYP3A inhibitor, is indicated for the treatment of mild-to-moderate coronavirus disease 2019 (COVID-19) in adults who are at high risk for progression to severe COVID-19, including hospitalization or death. ( 1 ) Limitations of Use PAXLOVID is not approved for use as pre-exposure or post-exposure prophylaxis for prevention of COVID-19. ( 1 ) Limitations of Use PAXLOVID is not approved for use as pre-exposure or post-exposure prophylaxis for prevention of COVID-19 [see Clinical Studies (14.3) ] .

    Dosage and Administration

    2 DOSAGE AND ADMINISTRATION PAXLOVID is nirmatrelvir tablets co-packaged with ritonavir tablets. ( 2.1 ) Nirmatrelvir must be co-administered with ritonavir. ( 2.1 )

  • Initiate PAXLOVID treatment as soon as possible after diagnosis of COVID-19 and within 5 days of symptom onset. ( 2.1 )
  • Administer orally with or without food. ( 2.1 )
  • Administer at approximately the same time each day. ( 2.2 , 2.3 )
  • Dosage: 300 mg nirmatrelvir (two 150 mg tablets) with 100 mg ritonavir (one 100 mg tablet), with all 3 tablets taken together twice daily for 5 days. ( 2.2 )
  • Dose Reduction for Renal Impairment ( 2.3 , 8.6 , 12.3 ) Abbreviation: eGFR=estimated glomerular filtration rate. Renal Function Days of Treatment Dose and Dose Frequency PAXLOVID should be administered at approximately the same time each day for 5 days. Moderate renal impairment (eGFR ≥30 to <60 mL/min) Days 1-5 150 mg nirmatrelvir (one 150 mg tablet) with 100 mg ritonavir (one 100 mg tablet) twice daily Severe renal impairment (eGFR <30 mL/min) including those requiring hemodialysis On days of hemodialysis, the PAXLOVID dose should be administered after hemodialysis. Day 1 300 mg nirmatrelvir (two 150 mg tablets) with 100 mg ritonavir (one 100 mg tablet) once Days 2-5 150 mg nirmatrelvir (one 150 mg tablet) with 100 mg ritonavir (one 100 mg tablet) once daily
  • PAXLOVID is not recommend in patients with severe hepatic impairment (Child-Pugh Class C). ( 2.4 , 8.7 ) 2.1 Important Dosage and Administration Information PAXLOVID is nirmatrelvir tablets co-packaged with ritonavir tablets. There are three different dose packs available:
  • PAXLOVID (nirmatrelvir; ritonavir) co-packaged for oral use 300 mg;100 mg [see Dosage and Administration (2.2) ] .
  • PAXLOVID (nirmatrelvir; ritonavir) co-packaged for oral use 150 mg;100 mg for patients with moderate renal impairment [see Dosage and Administration (2.3) ].
  • PAXLOVID (nirmatrelvir; ritonavir) co-packaged for oral use 300 mg;100 mg (Day 1) and 150 mg;100 mg (Days 2-5) for patients with severe renal impairment [see Dosage and Administration (2.3) ]. Nirmatrelvir must be co-administered with ritonavir. Failure to correctly co-administer nirmatrelvir with ritonavir may result in plasma levels of nirmatrelvir that are insufficient to achieve the desired therapeutic effect. Prescriptions should specify the numeric dose of each active ingredient within PAXLOVID [see Dosage and Administration (2.2 , 2.3 )]. Completion of the full 5-day treatment course and continued isolation in accordance with public health recommendations are important to maximize viral clearance and minimize transmission of SARS-CoV-2. The 5-day treatment course of PAXLOVID should be initiated as soon as possible after a diagnosis of COVID-19 has been made, and within 5 days of symptom onset even if baseline COVID-19 symptoms are mild. Should a patient require hospitalization due to severe or critical COVID-19 after starting treatment with PAXLOVID, the patient should complete...

    • Side Effects (Adverse Reactions)

    6 ADVERSE REACTIONS The following clinically significant adverse reactions are described elsewhere in the labeling:

  • Hypersensitivity reactions [see Warnings and Precautions (5.2) ] Most common adverse reactions (incidence ≥1% and greater incidence than in the placebo group) are dysgeusia and diarrhea. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Pfizer Inc. at 1-800-438-1985 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The safety of PAXLOVID is based on two Phase 2/3 randomized, placebo-controlled trials in symptomatic adult subjects 18 years of age and older with a laboratory confirmed diagnosis of SARS-CoV-2 infection. Subjects in both studies received PAXLOVID (nirmatrelvir/ritonavir 300 mg/100 mg) or placebo every 12 hours for 5 days for the treatment of mild-to-moderate COVID-19 within 5 days of symptom onset [see Clinical Studies (14) ] :
  • Trial C4671005 (EPIC-HR) enrolled subjects who were at high risk for progression to severe disease.
  • Trial C4671002 (EPIC-SR) enrolled subjects who were at standard risk for progression to severe disease (previously unvaccinated subjects at standard risk or fully vaccinated subjects with at least 1 risk factor for progression to severe disease). Adverse reactions were those reported while subjects were on study medication and through 28 days after the last dose of study treatment. In Trial C4671005 (EPIC-HR), 1,038 subjects received PAXLOVID and 1,053 subjects received placebo. The most common adverse reactions (≥1% incidence in the PAXLOVID group and occurring at a greater frequency than in the placebo group) were dysgeusia (5% and <1%, respectively) and diarrhea (3% and 2%, respectively). Among vaccinated or unvaccinated subjects at standard risk or fully vaccinated subjects with at least 1 risk factor for progression to severe disease in Trial C4671002 (EPIC-SR), 540 subjects received PAXLOVID and 528 subjects received placebo. The adverse reactions observed were consistent with those observed in EPIC-HR. Trial C4671028 (EPIC-SRI) was a Phase 1, open-label trial that evaluated the effects of severe renal impairment on the pharmacokinetics, safety, and tolerability of PAXLOVID in non-hospitalized adult participants with COVID-19 and severe renal impairment. A total of 15 subjects with severe renal impairment were enrolled in this trial, with 12 subjects receiving intermittent hemodialysis and 3 subjects not on hemodialysis. Subjects received nirmatrelvir/ritonavir 300 mg/100 mg once on Day 1 followed by nirmatrelvir/ritonavir 150 mg/100 mg once daily from Days 2-5. The safety profile of PAXLOVID in subjects with severe renal impairment, including those requiring hemodialysis, was consistent with the safety profile observed in the Phase 2/3 randomized, placebo-controlled trials. Emergency Use Authorization Experience in Subjects with COVID-19 The following adverse reactions have been identified during use of PAXLOVID under Emergency Use Authorization. Immune System Disorders: Anaphylaxis, hypersensitivity reactions [see Warnings and Precautions (5.2) ] Skin and Subcutaneous Tissue Disorders: Toxic epidermal necrolysis, Stevens-Johnson syndrome [see Warnings and Precautions (5.2) ] Nervous System Disorders: Headache Vascular Disorders: Hypertension Gastrointestinal Disorders: Abdominal pain, nausea, vomiting General Disorders and Administration Site Conditions: Malaise

    • Drug Interactions

    7 DRUG INTERACTIONS Co-administration of PAXLOVID can alter the plasma concentrations of other drugs and other drugs may alter the plasma concentrations of PAXLOVID. Consider the potential for drug interactions prior to and during PAXLOVID therapy and review concomitant medications during PAXLOVID therapy. ( 4 , 5.1 , 7 , 12.3 ) 7.1 Potential for PAXLOVID to Affect Other Drugs 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 [see Contraindications (4) and Drug Interactions (7.3) Table 2 ] . Co-administration with other CYP3A substrates may require a dose adjustment or additional monitoring as shown in Table 2. 7.2 Potential for Other Drugs to Affect PAXLOVID Nirmatrelvir and ritonavir are CYP3A substrates; therefore, drugs that induce CYP3A may decrease nirmatrelvir and ritonavir plasma concentrations and reduce PAXLOVID therapeutic effect [see Contraindications (4) and Drug Interactions (7.3) Table 2 ] . 7.3 Established and Other Potentially Significant Drug Interactions Table 2 provides a listing of clinically significant drug interactions, including contraindicated drugs [see Contraindications (4) and Warnings and Precautions (5.1) ] . Drugs listed in Table 2 are a guide and not considered a comprehensive list of all possible drugs that may interact with PAXLOVID. The healthcare provider should consult other appropriate resources such as the prescribing information for the interacting drug for comprehensive information on dosing or monitoring with concomitant use of a strong CYP3A inhibitor such as ritonavir. Table 2: Established and Other Potentially Significant Drug Interactions Drug Class Drugs within Class Effect on Concentration Clinical Comments Alpha 1- adrenoreceptor antagonist alfuzosin ↑ alfuzosin Co-administration contraindicated due to potential hypotension [see Contraindications (4) ] . Alpha 1- adrenoreceptor antagonist tamsulosin ↑ tamsulosin Avoid concomitant use with PAXLOVID. Antianginal ranolazine ↑ ranolazine Co-administration contraindicated due to potential for serious and/or life-threatening reactions [see Contraindications (4) ] . Antiarrhythmics amiodarone, dronedarone, flecainide, propafenone, quinidine ↑ antiarrhythmic Co-administration contraindicated due to potential for cardiac arrhythmias [see Contraindications (4) ] . Antiarrhythmics lidocaine (systemic), disopyramide ↑ antiarrhythmic Caution is warranted and therapeutic concentration monitoring is recommended for antiarrhythmics if available. Anticancer...

    Contraindications

    4 CONTRAINDICATIONS PAXLOVID is contraindicated in patients with a history of clinically significant hypersensitivity reactions [e.g., toxic epidermal necrolysis (TEN) or Stevens-Johnson syndrome] to its active ingredients (nirmatrelvir or ritonavir) or any other components of the product. PAXLOVID is contraindicated with drugs that are primarily metabolized by CYP3A and for which elevated concentrations are associated with serious and/or life-threatening reactions and drugs that are strong CYP3A inducers where significantly reduced nirmatrelvir or ritonavir plasma concentrations may be associated with the potential for loss of virologic response and possible resistance. There are certain other drugs for which concomitant use with PAXLOVID should be avoided and/or dose adjustment, interruption, or therapeutic monitoring is recommended. Drugs listed in this section are a guide and not considered a comprehensive list of all drugs that may be contraindicated with PAXLOVID. The healthcare provider should consult other appropriate resources such as the prescribing information for the interacting drug for comprehensive information on dosing or monitoring with concomitant use of a strong CYP3A inhibitor like PAXLOVID [see Drug Interactions (7.3) ] : ➢ Drugs that are primarily metabolized by CYP3A for which elevated concentrations are associated with serious and/or life-threatening reactions [see Drug Interactions (7.3) ] :

  • Alpha 1-adrenoreceptor antagonist: alfuzosin
  • Antianginal: ranolazine
  • Antiarrhythmic: amiodarone, dronedarone, flecainide, propafenone, quinidine
  • Anti-gout: colchicine (in patients with renal and/or hepatic impairment [see Table 2 , Drug Interactions (7.3)] )
  • Antipsychotics: lurasidone, pimozide
  • Benign prostatic hyperplasia agents: silodosin
  • Cardiovascular agents: eplerenone, ivabradine
  • Ergot derivatives: dihydroergotamine, ergotamine, methylergonovine
  • HMG-CoA reductase inhibitors: lovastatin, simvastatin (these drugs can be temporarily...

    • Pregnancy and Breastfeeding

    8.1 Pregnancy Risk Summary Available data on the use of nirmatrelvir during pregnancy are insufficient to evaluate for a drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes. Published observational studies on ritonavir use in pregnant women have not identified an increase in the risk of major birth defects. Published studies with ritonavir are insufficient to identify a drug associated risk of miscarriage (see Data ). There are maternal and fetal risks associated with untreated COVID-19 in pregnancy (see Clinical Considerations ). In an embryo-fetal development study with nirmatrelvir, reduced fetal body weights following oral administration of nirmatrelvir to pregnant rabbits were observed at systemic exposures (AUC) approximately 11 times higher than clinical exposure at the approved human dose of PAXLOVID. No other adverse developmental outcomes were observed in animal reproduction studies with nirmatrelvir at systemic exposures (AUC) greater than or equal to 3 times higher than clinical exposure at the approved human dose of PAXLOVID (see Data ) . In embryo-fetal developmental studies with ritonavir, no evidence of adverse developmental outcomes was observed following oral administration of ritonavir to pregnant rats and rabbits at systemic exposures (AUC) 5 (rat) or 8 (rabbits) times higher than clinical exposure at the approved human dose of PAXLOVID (see Data ) . The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. Clinical Considerations Disease-associated Maternal and/or Embryo-fetal Risk COVID-19 in pregnancy is associated with adverse maternal and fetal outcomes, including preeclampsia, eclampsia,...

    Overdosage

    10 OVERDOSAGE Treatment of overdose with PAXLOVID should consist of general supportive measures including monitoring of vital signs and observation of the clinical status of the patient. There is no specific antidote for overdose with PAXLOVID.

    How Supplied

    16 HOW SUPPLIED/STORAGE AND HANDLING How Supplied PAXLOVID is nirmatrelvir tablets co-packaged with ritonavir tablets. It is supplied in three different Dose Packs. Nirmatrelvir tablets and ritonavir tablets are supplied in separate blister cavities within the same child-resistant blister card. Dose Pack Content NDC Description 300 mg nirmatrelvir; 100 mg ritonavir Each Carton Contains: 30 tablets divided in 10 blister cards 0069-5045-30 Nirmatrelvir tablets: Oval, pink immediate-release, film-coated tablets debossed with "PFE" on one side and "3CL" on the other side. Ritonavir tablets: White to off-white, capsule-shaped, film-coated tablets debossed with "H" on one side and “R9” on the other side. Or 0069-5321-30 Nirmatrelvir tablets: Oval, pink immediate-release, film-coated tablets debossed with "PFE" on one side and "3CL" on the other side. Ritonavir tablets: White film-coated ovaloid tablets debossed with "NK" on one side. Each Blister Card Contains: 2 nirmatrelvir tablets (150 mg each) and 1 ritonavir tablet (100 mg) 0069-5045-06 Nirmatrelvir tablets: Oval, pink immediate-release, film-coated tablets debossed with "PFE" on one side and "3CL" on the other side. Ritonavir tablets: White to off-white, capsule-shaped, film-coated tablets debossed with "H" on one side and “R9” on the other side. Or 0069-5321-03 Nirmatrelvir tablets: Oval, pink immediate-release, film-coated tablets debossed with "PFE" on one side and "3CL" on the other side. Ritonavir tablets: White film-coated ovaloid tablets debossed with "NK" on one side. 150 mg nirmatrelvir; 100 mg ritonavir Each Carton Contains: 20 tablets divided in 10 blister cards 0069-5317-20 Nirmatrelvir tablets: Oval, pink immediate-release, film-coated tablets debossed with "PFE" on one side and "3CL" on the other side. Ritonavir tablets: White film-coated ovaloid tablets debossed with “NK” on one side. Or 0069-5434-20 Nirmatrelvir tablets: Oval, pink immediate‑release, film‑coated tablets debossed with "PFE" on one...

    About This Information

    This drug information is sourced from FDA-approved labeling via the openFDA database. It is intended for educational and reference purposes only. This is not medical advice. Always consult your healthcare provider before making decisions about medication. Drug information may be updated by the FDA; check with your pharmacist for the most current information.

    What are side effects?

    Side effects are unwanted reactions that can occur when taking a medication. They range from mild (headache, nausea) to severe (allergic reactions, organ damage). Not everyone experiences side effects, and severity varies. Report any concerning side effects to your doctor.

    What are drug interactions?

    Drug interactions occur when a medication is affected by another drug, food, or supplement. Interactions can make medications less effective or cause dangerous side effects. Always tell your doctor about all medications and supplements you take.