Drug Interactions | PAXLOVID™ (nirmatrelvir tablets; ritonavir tablets)

Drug Class	Drugs within Class that are Contraindicated	Effect on Concentration	Clinical Comments
Table 1: Established and Other Potentially Significant Drug Interactions
Alpha₁-adrenoreceptor antagonist	alfuzosin	↑ alfuzosin	Coadministration contraindicated due to potential hypotension [see Contraindications (4)].
Alpha₁-adrenoreceptor antagonist	tamsulosin	↑ tamsulosin	Avoid concomitant use with PAXLOVID.
Antianginal	ranolazine	↑ ranolazine	Coadministration contraindicated due to potential for serious and/or life-threatening reactions [see Contraindications (4)].
Antiarrhythmics	amiodarone, dronedarone, flecainide, propafenone, quinidine	↑ antiarrhythmic	Coadministration 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 drugs	apalutamide	↓ nirmatrelvir/ritonavir	Coadministration contraindicated due to potential loss of virologic response and possible resistance [see Contraindications (4)].
Anticancer drugs	abemaciclib, ceritinib, dasatinib, encorafenib, ibrutinib, ivosidenib, neratinib, nilotinib, venetoclax, vinblastine, vincristine	↑ anticancer drug	Avoid coadministration of encorafenib or ivosidenib due to potential risk of serious adverse events such as QT interval prolongation. Avoid use of neratinib, venetoclax or ibrutinib. Coadministration of vincristine and vinblastine may lead to significant hematologic or gastrointestinal side effects. For further information, refer to individual product label for anticancer drug.
Anticoagulants	warfarin rivaroxaban dabigatran^a apixaban	↑↓ warfarin ↑ rivaroxaban ↑ dabigatran ↑ apixaban	Closely monitor INR if coadministration with warfarin is necessary. Increased bleeding risk with rivaroxaban. Avoid concomitant use. Increased bleeding risk with dabigatran. Depending on dabigatran indication and renal function, reduce dose of dabigatran or avoid concomitant use. Refer to the dabigatran product label for further information. Combined P-gp and strong CYP3A4 inhibitors increase blood levels of apixaban and increase the risk of bleeding. Dosing recommendations for coadministration of apixaban with PAXLOVID depend on the apixaban dose. Refer to the apixaban product label for more information.
Anticonvulsants	carbamazepine,^a phenobarbital, primidone, phenytoin	↓ nirmatrelvir/ritonavir	Coadministration contraindicated due to potential loss of virologic response and possible resistance [see Contraindications (4)].
Anticonvulsants	clonazepam	↑ anticonvulsant	A dose decrease may be needed for clonazepam when coadministered with PAXLOVID and clinical monitoring is recommended.
Antidepressants	bupropion trazodone	↓ bupropion and active metabolite hydroxy-bupropion ↑ trazodone	Monitor for an adequate clinical response to bupropion. Adverse reactions of nausea, dizziness, hypotension, and syncope have been observed following coadministration of trazodone and ritonavir. A lower dose of trazodone should be considered. Refer to trazadone product label for further information.
Antifungals	voriconazole, ketoconazole, isavuconazonium sulfate itraconazole^a	↓ voriconazole ↑ ketoconazole ↑ isavuconazonium sulfate ↑ itraconazole ↑ nirmatrelvir/ritonavir	Avoid concomitant use of voriconazole. Refer to ketoconazole, isavuconazonium sulfate, and itraconazole product labels for further information.
Anti-gout	colchicine	↑ colchicine	Coadministration contraindicated due to potential for serious and/or life-threatening reactions in patients with renal and/or hepatic impairment [see Contraindications (4)].
Anti-HIV protease inhibitors	atazanavir, darunavir, tipranavir	↑ protease inhibitor	For further information, refer to the respective protease inhibitors’ prescribing information. Patients on ritonavir- or cobicistat-containing HIV regimens should continue their treatment as indicated. Monitor for increased PAXLOVID or protease inhibitor adverse events [see Dosage and Administration (2.4)].
Anti-HIV	efavirenz, maraviroc, nevirapine, zidovudine bictegravir/ emtricitabine/ tenofovir	↑ efavirenz ↑ maraviroc ↑ nevirapine ↓ zidovudine ↑ bictegravir ⟷emtricitabine ↑ tenofovir	For further information, refer to the respective anti-HIV drugs prescribing information.
Anti-infective	clarithromycin, erythromycin	↑ clarithromycin ↑ erythromycin	Refer to the respective prescribing information for anti-infective dose adjustment.
Antimycobacterial	rifampin	↓ nirmatrelvir/ritonavir	Coadministration contraindicated due to potential loss of virologic response and possible resistance. Alternate antimycobacterial drugs such as rifabutin should be considered [see Contraindications (4)].
Antimycobacterial	bedaquiline rifabutin rifapentine	↑ bedaquiline ↑ rifabutin ↓ nirmatrelvir/ritonavir	Refer to the bedaquiline product label for further information. Refer to rifabutin product label for further information on rifabutin dose reduction. Avoid concomitant use with PAXLOVID.
Antipsychotics	lurasidone, pimozide	↑ lurasidone ↑ pimozide	Coadministration contraindicated due to serious and/or life-threatening reactions such as cardiac arrhythmias [see Contraindications (4)].
Antipsychotics	quetiapine clozapine	↑ quetiapine ↑ clozapine	If coadministration is necessary, reduce quetiapine dose and monitor for quetiapine-associated adverse reactions. Refer to the quetiapine prescribing information for recommendations. If coadministration is necessary, consider reducing the clozapine dose and monitor for adverse reactions.
Benign prostatic hyperplasia agents	silodosin	↑ silodosin	Coadministration contraindicated due to potential for postural hypotension [see Contraindications (4)].
Calcium channel blockers	amlodipine, diltiazem, felodipine, nicardipine, nifedipine, verapamil	↑ calcium channel blocker	Caution is warranted and clinical monitoring of patients is recommended. A dose decrease may be needed for these drugs when coadministered with PAXLOVID. If coadministered, refer to individual product label for calcium channel blocker for further information.
Cardiac glycosides	digoxin	↑ digoxin	Caution should be exercised when coadministering PAXLOVID with digoxin, with appropriate monitoring of serum digoxin levels. Refer to the digoxin product label for further information.
Cardiovascular agents	eplerenone ivabradine	↑ eplerenone ↑ ivabradine	Coadministration with eplerenone is contraindicated due to potential for hyperkalemia [see Contraindications (4)]. Coadministration with ivabradine is contraindicated due to potential for bradycardia or conduction disturbances [see Contraindications (4)].
Cardiovascular agents	aliskiren, ticagrelor, vorapaxar clopidogrel cilostazol	↑ aliskiren ↑ ticagrelor ↑ vorapaxar ↓ clopidogrel active metabolite ↑ cilostazol	Avoid concomitant use with PAXLOVID. Dosage adjustment of cilostazol is recommended. Refer to the cilostazol product label for more information.
Corticosteroids primarily metabolized by CYP3A	betamethasone, budesonide, ciclesonide, dexamethasone, fluticasone, methylprednisolone, mometasone, triamcinolone	↑ corticosteroid	Coadministration with corticosteroids (all routes of administration) of which exposures are significantly increased by strong CYP3A inhibitors can increase the risk for Cushing’s syndrome and adrenal suppression. However, the risk of Cushing’s syndrome and adrenal suppression associated with short-term use of a strong CYP3A4 inhibitor is low. Alternative corticosteroids including beclomethasone, prednisone, and prednisolone should be considered.
Cystic fibrosis transmembrane conductance regulator potentiators	lumacaftor/ivacaftor	↓ nirmatrelvir/ritonavir	Coadministration contraindicated due to potential loss of virologic response and possible resistance [see Contraindications (4)].
Cystic fibrosis transmembrane conductance regulator potentiators	ivacaftor elexacaftor/tezacaftor/ivacaftor tezacaftor/ivacaftor	↑ ivacaftor ↑elexacaftor/tezacaftor/ivacaftor ↑ tezacaftor/ivacaftor	Reduce dosage when coadministered with PAXLOVID. Refer to individual product labels for more information.
Dipeptidyl peptidase 4 (DPP4) inhibitors	saxagliptin	↑ saxagliptin	Dosage adjustment of saxagliptin is recommended. Refer to the saxagliptin product label for more information.
Endothelin receptor antagonists	bosentan	↑ bosentan	Discontinue use of bosentan at least 36 hours prior to initiation of PAXLOVID. Refer to the bosentan product label for further information.
Ergot derivatives	dihydroergotamine, ergotamine, methylergonovine	↑ dihydroergotamine ↑ ergotamine ↑ methylergonovine	Coadministration contraindicated due to potential for acute ergot toxicity characterized by vasospasm and ischemia of the extremities and other tissues including the central nervous system [see Contraindications (4)].
Hepatitis C direct-acting antivirals	elbasvir/grazoprevir, glecaprevir/pibrentasvir ombitasvir/paritaprevir/ ritonavir and dasabuvir sofosbuvir/velpatasvir/ voxilaprevir	↑ antiviral	Increased grazoprevir concentrations can result in ALT elevations. Avoid concomitant use of glecaprevir/pibrentasvir with PAXLOVID. Refer to the ombitasvir/paritaprevir/ritonavir and dasabuvir label for further information. Refer to the sofosbuvir/velpatasvir/voxilaprevir product label for further information. Patients on ritonavir-containing HCV regimens should continue their treatment as indicated. Monitor for increased PAXLOVID or HCV drug adverse events with concomitant use [see Dosage and Administration (2.4)].
Herbal products	St John’s Wort (hypericum perforatum)	↓ nirmatrelvir/ritonavir	Coadministration contraindicated due to potential loss of virologic response and possible resistance [see Contraindications (4)].
HMG-CoA reductase inhibitors	lovastatin, simvastatin	↑ lovastatin ↑ simvastatin	Coadministration contraindicated due to potential for myopathy including rhabdomyolysis [see Contraindications (4)]. Discontinue use of lovastatin and simvastatin at least 12 hours prior to initiation of PAXLOVID, during the 5 days of PAXLOVID treatment and for 5 days after completing PAXLOVID.
HMG-CoA reductase inhibitors	atorvastatin, rosuvastatin	↑ atorvastatin, ↑ rosuvastatin	Consider temporary discontinuation of atorvastatin and rosuvastatin during treatment with PAXLOVID. Atorvastatin and rosuvastatin do not need to be held prior to or after completing PAXLOVID.
Hormonal contraceptive	ethinyl estradiol	↓ ethinyl estradiol	An additional, nonhormonal method of contraception should be considered during the 5 days of PAXLOVID treatment and until one menstrual cycle after stopping PAXLOVID.
Immunosuppressants	voclosporin	↑ voclosporin	Coadministration contraindicated due to potential for acute and/or chronic nephrotoxicity [see Contraindications (4)].
Immunosuppressants	cyclosporine, tacrolimus everolimus, sirolimus	↑ cyclosporine ↑ tacrolimus ↑ everolimus ↑ sirolimus	Avoid use of PAXLOVID when close monitoring of immunosuppressant concentrations is not feasible. If coadministered, dose adjustment of the immunosuppressant and monitoring for immunosuppressant concentrations and immunosuppressant-associated adverse reactions is recommended. Refer to the individual immunosuppressant product label for further information and obtain expert consultation from the patient’s immunosuppressive therapy specialist. Avoid concomitant use of everolimus and sirolimus and PAXLOVID.
Janus kinase (JAK) inhibitors	tofacitinib, upadacitinib	↑ tofacitinib ↑ upadacitinib	Dosage adjustment of tofacitinib is recommended. Refer to the tofacitinib product label for more information. Dosing recommendations for coadministration of upadacitinib with PAXLOVID depends on the upadacitinib indication. Refer to the upadacitinib product label for more information.
Long-acting beta-adrenoceptor agonist	salmeterol	↑ salmeterol	Avoid concomitant use with PAXLOVID. The combination may result in increased risk of cardiovascular adverse events associated with salmeterol, including QT prolongation, palpitations, and sinus tachycardia.
Microsomal triglyceride transfer protein (MTTP) inhibitor	lomitapide	↑ lomitapide	Coadministration contraindicated due to potential for hepatotoxicity and gastrointestinal adverse reactions [see Contraindications (4)].
Migraine medications	eletriptan ubrogepant	↑ eletriptan ↑ ubrogepant	Coadministration of eletriptan within at least 72 hours of PAXLOVID is contraindicated due to potential for serious adverse reactions including cardiovascular and cerebrovascular events [see Contraindications (4)]. Coadministration of ubrogepant with PAXLOVID is contraindicated due to potential for serious adverse reactions [see Contraindications (4)].
Migraine medications	rimegepant	↑ rimegepant	Avoid concomitant use with PAXLOVID.
Mineralocorticoid receptor antagonists	finerenone	↑ finerenone	Coadministration contraindicated due to potential for serious adverse reactions including hyperkalemia, hypotension, and hyponatremia [see Contraindications (4)].
Muscarinic receptor antagonists	darifenacin	↑ darifenacin	The darifenacin daily dose should not exceed 7.5 mg when coadministered with PAXLOVID. Refer to the darifenacin product label for more information.
Narcotic analgesics	fentanyl, hydrocodone, oxycodone, meperidine methadone	↑ fentanyl ↑ hydrocodone ↑ oxycodone ↑ meperidine ↓ methadone	Careful monitoring of therapeutic and adverse effects (including potentially fatal respiratory depression) is recommended when fentanyl, hydrocodone, oxycodone, or meperidine is concomitantly administered with PAXLOVID. If concomitant use with PAXLOVID is necessary, consider a dosage reduction of the narcotic analgesic and monitor patients closely at frequent intervals. Refer to the individual product label for more information. Monitor methadone-maintained patients closely for evidence of withdrawal effects and adjust the methadone dose accordingly.
Neuropsychiatric agents	suvorexant aripiprazole, brexpiprazole, cariprazine, iloperidone, lumateperone, pimavanserin	↑ suvorexant ↑ aripiprazole ↑ brexpiprazole ↑ cariprazine ↑ iloperidone ↑ lumateperone ↑ pimavanserin	Avoid concomitant use of suvorexant with PAXLOVID. Dosage adjustment of aripiprazole, brexpiprazole, cariprazine, iloperidone, lumateperone, and pimavanserin is recommended. Refer to individual product label for more information.
Pulmonary hypertension agents (PDE5 inhibitors)	sildenafil (Revatio^®)	↑ sildenafil	Coadministration of sildenafil with PAXLOVID is contraindicated due to the potential for sildenafil associated adverse events, including visual abnormalities, hypotension, prolonged erection, and syncope [see Contraindications (4)].
Pulmonary hypertension agents (PDE5 inhibitors) Pulmonary hypertension agents (sGC stimulators)	tadalafil (Adcirca^®) riociguat	↑ tadalafil ↑ riociguat	Avoid concomitant use of tadalafil with PAXLOVID. Dosage adjustment is recommended for riociguat. Refer to the riociguat product label for more information.
Erectile dysfunction agents (PDE5 inhibitors)	avanafil sildenafil, tadalafil, vardenafil	↑ avanafil ↑ sildenafil ↑ tadalafil ↑ vardenafil	Do not use PAXLOVID with avanafil because a safe and effective avanafil dosage regimen has not been established. Dosage adjustment is recommended for use of sildenafil, tadalafil, or vardenafil with PAXLOVID. Refer to individual product label for more information.
Opioid antagonists	naloxegol	↑ naloxegol	Coadministration contraindicated due to the potential for opioid withdrawal symptoms [see Contraindications (4)].
Sedative/hypnotics	triazolam, oral midazolam^a	↑ triazolam ↑ midazolam	Coadministration contraindicated due to potential for extreme sedation and respiratory depression [see Contraindications (4)].
Sedative/hypnotics	buspirone, clorazepate, diazepam, estazolam, flurazepam, zolpidem midazolam (administered parenterally)	↑ sedative/hypnotic ↑ midazolam	A dose decrease may be needed for these drugs when coadministered with PAXLOVID and monitoring for adverse events. Coadministration of midazolam (parenteral) should be done in a setting which ensures close clinical monitoring and appropriate medical management in case of respiratory depression and/or prolonged sedation. Dosage reduction for midazolam should be considered, especially if more than a single dose of midazolam is administered. Refer to the midazolam product label for further information.
Serotonin receptor 1A agonist/ serotonin receptor 2A antagonist	flibanserin	↑ flibanserin	Coadministration contraindicated due to potential for hypotension, syncope, and CNS depression [see Contraindications (4)].
Vasopressin receptor antagonists	tolvaptan	↑ tolvaptan	Coadministration contraindicated due to potential for dehydration, hypovolemia and hyperkalemia [see Contraindications (4)].

^aSee Pharmacokinetics, Drug Interaction Studies Conducted with Nirmatrelvir and Ritonavir (12.3).

Tablet	Embossed Text
nirmatrelvir	Front: 3CL \| Back: PFE
ritonavir, manufactured by AbbVie	Front: NK \| Back: No text
ritonavir, manufactured by Hetero	Front: H \| Back: R9

AUTHORIZED USE

The U.S. Food and Drug Administration (FDA) has issued an Emergency Use Authorization (EUA) for the emergency use of the unapproved product PAXLOVID for the treatment of adults and pediatric patients (12 years of age and older weighing at least 40 kg) with a current diagnosis of mild-to-moderate coronavirus disease 2019 (COVID-19) and who are at high risk for progression to severe COVID-19, including hospitalization or death.

LIMITATIONS OF AUTHORIZED USE

PAXLOVID is not authorized for initiation of treatment in patients requiring hospitalization due to severe or critical COVID-19
PAXLOVID is not authorized for use as pre-exposure or post-exposure prophylaxis for prevention of
COVID-19
PAXLOVID is not authorized for use for longer than 5 consecutive days

PAXLOVID may be prescribed for an individual patient by physicians, advanced practice registered nurses, and physician assistants that are licensed or authorized under state law to prescribe drugs.

PAXLOVID may also be prescribed for an individual patient by a state-licensed pharmacist under the following conditions:

Sufficient information is available, such as through access to health records less than 12 months old or consultation with a health care provider in an established provider-patient relationship with the individual patient, to assess renal and hepatic function; and
Sufficient information is available, such as through access to health records, patient reporting of medical history, or consultation with a health care provider in an established provider-patient relationship with the individual patient, to obtain a comprehensive list of medications (prescribed and non-prescribed) that the patient is taking to assess for potential drug interaction.

The state-licensed pharmacist should refer an individual patient for clinical evaluation (e.g., telehealth, in-person visit) with a physician, advanced practice registered nurse, or physician assistant licensed or authorized under state law to prescribe drugs, if any of the following apply:

Sufficient information is not available to assess renal and hepatic function.
Sufficient information is not available to assess for a potential drug interaction.
Modification of other medications is needed due to a potential drug interaction.
PAXLOVID is not an appropriate therapeutic option based on the authorized Fact Sheet for Healthcare Providers or due to potential drug interactions for which recommended monitoring would not be feasible.

PAXLOVID is not approved for any use, including for use for the treatment of COVID-19.

PAXLOVID is authorized only for the duration of the declaration that circumstances exist justifying the authorization of the emergency use of PAXLOVID under 564(b)(1) of the Food Drug and Cosmetic Act unless the authorization is terminated or revoked sooner.

IMPORTANT SAFETY
INFORMATION

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IMPORTANT SAFETY INFORMATION

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PAXLOVID is contraindicated in patients with a history of clinically significant hypersensitivity reactions (eg, toxic epidermal necrolysis [TEN] or Stevens-Johnson syndrome) to its active ingredients (nirmatrelvir or ritonavir) or any other components of the product.

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 such as ritonavir.

PAXLOVID is contraindicated with drugs that are highly dependent on CYP3A for clearance and for which elevated concentrations are associated with serious and/or life-threatening reactions:

Alpha₁-adrenoreceptor antagonist: alfuzosin
Antianginal: ranolazine
Antiarrhythmic: amiodarone, dronedarone, flecainide, propafenone, quinidine
Anti-gout: colchicine
Antipsychotics: lurasidone, pimozide
Benign prostatic hyperplasia agents: silodosin
Cardiovascular agents: eplerenone, ivabradine
Ergot derivatives: dihydroergotamine, ergotamine, methylergonovine
HMG-CoA reductase inhibitors: lovastatin, simvastatin
Immunosuppressants: voclosporin
Microsomal triglyceride transfer protein inhibitor: lomitapide
Migraine medications: eletriptan, ubrogepant
Mineralocorticoid receptor antagonists: finerenone
Opioid antagonists: naloxegol
PDE5 inhibitor: sildenafil (Revatio^®) when used for pulmonary arterial hypertension
Sedative/hypnotics: triazolam, oral midazolam
Serotonin receptor 1A agonist/serotonin receptor 2A antagonist: flibanserin
Vasopressin receptor antagonists: tolvaptan

PAXLOVID is contraindicated with drugs that are potent CYP3A inducers where significantly reduced nirmatrelvir or ritonavir plasma concentrations may be associated with the potential for loss of virologic response and possible resistance. PAXLOVID cannot be started immediately after discontinuation of any of the following medications due to the delayed offset of the recently discontinued CYP3A inducer:

Anticancer drugs: apalutamide
Anticonvulsant: carbamazepine, phenobarbital, primidone, phenytoin
Cystic fibrosis transmembrane conductance regulator potentiators: lumacaftor/ivacaftor
Antimycobacterials: rifampin
Herbal Products: St. John’s Wort (hypericum perforatum)

There are limited clinical data available for PAXLOVID. Serious and unexpected adverse events may occur that have not been previously reported with PAXLOVID use.

Risk of Serious Adverse Reactions Due to Drug Interactions: Initiation of PAXLOVID, a CYP3A inhibitor, in patients receiving medications metabolized by CYP3A or initiation of medications metabolized by CYP3A in patients already receiving PAXLOVID, may increase plasma concentrations of medications metabolized by CYP3A. Initiation of medications that inhibit or induce CYP3A may increase or decrease concentrations of PAXLOVID, respectively. These interactions may lead to:

Clinically significant adverse reactions, potentially leading to severe, life-threatening, or fatal events from greater exposures of concomitant medications
Clinically significant adverse reactions from greater exposures of PAXLOVID
Loss of therapeutic effect of PAXLOVID and possible development of viral resistance

Consult Table 1 of the Fact Sheet for Healthcare Providers for clinically significant drug interactions, including contraindicated drugs. Drugs listed in Table 1 are a guide and not considered a comprehensive list of all possible drugs that may interact with PAXLOVID. Consider the potential for drug interactions prior to and during PAXLOVID therapy; review concomitant medications during PAXLOVID therapy and monitor for the adverse reactions associated with the concomitant medications.

Anaphylaxis and other hypersensitivity reactions have been reported with PAXLOVID. Cases of Toxic Epidermal Necrolysis and Stevens-Johnson syndrome have been reported with ritonavir, a component of PAXLOVID (refer to NORVIR prescribing information). If signs and symptoms of a clinically significant hypersensitivity reaction or anaphylaxis occur, immediately discontinue PAXLOVID and initiate appropriate medications and/or supportive care.

Hepatotoxicity: Hepatic transaminase elevations, clinical hepatitis, and jaundice have occurred in patients receiving ritonavir. Therefore, caution should be exercised when administering PAXLOVID to patients with pre-existing liver diseases, liver enzyme abnormalities, or hepatitis.

Because nirmatrelvir is co-administered with ritonavir, there may be a risk of HIV-1 developing resistance to HIV protease inhibitors in individuals with uncontrolled or undiagnosed HIV-1 infection.

Adverse events in the PAXLOVID group (≥1%) that occurred at a greater frequency (≥5 subject difference) than in the placebo group were dysgeusia (6% and <1%, respectively), diarrhea (3% and 2%), hypertension (1% and <1%), and myalgia (1% and <1%). The proportions of subjects who discontinued treatment due to an adverse event were 2% in the PAXLOVID group and 4% in the placebo group.

The following adverse reactions have been identified during post-authorization use of PAXLOVID. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Immune System Disorders: Anaphylaxis, hypersensitivity reactions
Gastrointestinal Disorders: Abdominal pain, nausea
General Disorders and Administration Site Conditions: Malaise

Required Reporting for Serious Adverse Events and Medication Errors: The prescribing healthcare provider and/or the provider’s designee is/are responsible for mandatory reporting of all serious adverse events and medication errors potentially related to PAXLOVID within 7 calendar days from the healthcare provider's awareness of the event.

Submit adverse event and medication error reports to FDA MedWatch using one of the following methods:

Online: https://www.fda.gov/medwatch/report.htm
Complete and submit a postage-paid FDA Form 3500 and returning by mail/fax
Call 1-800-FDA-1088 to request a reporting form

In addition, please provide a copy of all FDA MedWatch forms to: www.pfizersafetyreporting.com, or by fax (1‑866‑635‑8337) or phone (1‑800‑438‑1985).

PAXLOVID is a strong inhibitor of CYP3A and may increase plasma concentrations of drugs that are primarily metabolized by CYP3A. 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.

Nirmatrelvir and ritonavir are CYP3A substrates; therefore, drugs that induce CYP3A may decrease nirmatrelvir and ritonavir plasma concentrations and reduce PAXLOVID therapeutic effect.

Pregnancy: There are no available human data on the use of nirmatrelvir during pregnancy 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. There are maternal and fetal risks associated with untreated COVID-19 in pregnancy.

Lactation: There are no available data on the presence of nirmatrelvir in human or animal milk, the effects on the breastfed infant, or the effects on milk production. A transient decrease in body weight was observed in the nursing offspring of rats administered nirmatrelvir. Limited published data reports that ritonavir is present in human milk. There is no information on the effects of ritonavir on the breastfed infant or the effects of the drug on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for PAXLOVID and any potential adverse effects on the breastfed infant from PAXLOVID or from the underlying maternal condition. Breastfeeding individuals with COVID-19 should follow practices according to clinical guidelines to avoid exposing the infant to COVID-19.

Contraception: Use of ritonavir may reduce the efficacy of combined hormonal contraceptives. Advise patients using combined hormonal contraceptives to use an effective alternative contraceptive method or an additional barrier method of contraception.

Pediatrics: PAXLOVID is not authorized for use in pediatric patients younger than 12 years of age or weighing less than 40 kg. The safety and effectiveness of PAXLOVID have not been established in pediatric patients. The authorized adult dosing regimen is expected to result in comparable serum exposures of nirmatrelvir and ritonavir in patients 12 years of age and older and weighing at least 40 kg as observed in adults, and adults with similar body weight were included in the trial EPIC-HR.

Systemic exposure of nirmatrelvir increases in renally impaired patients with increase in the severity of renal impairment. No dosage adjustment is needed in patients with mild renal impairment. In patients with moderate renal impairment (eGFR ≥30 to <60 mL/min), reduce the dose of PAXLOVID to 150 mg nirmatrelvir and 100 mg ritonavir twice daily for 5 days. Prescriptions should specify the numeric dose of each active ingredient within PAXLOVID. Providers should counsel patients about renal dosing instructions. PAXLOVID is not recommended in patients with severe renal impairment (eGFR <30 mL/min based on CKD-EPI formula) until more data are available; the appropriate dosage for patients with severe renal impairment has not been determined.

No dosage adjustment of PAXLOVID is needed for patients with either mild (Child-Pugh Class A) or moderate (Child-Pugh Class B) hepatic impairment. No pharmacokinetic or safety data are available regarding the use of nirmatrelvir or ritonavir in subjects with severe hepatic impairment (Child-Pugh Class C); therefore, PAXLOVID is not recommended for use in patients with severe hepatic impairment.

Please see Fact Sheet for Healthcare Providers and Fact Sheet for Patients, Parents, and Caregivers.