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. For contraindicated drug interactions reference Table 1 of PAXLOVID Product Insert.

Risk of Serious Adverse Reactions Due to Drug Interactions

Initiation of PAXLOVID, which contains ritonavir, a strong 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.

Medications that induce CYP3A may decrease concentrations of PAXLOVID.

These interactions may lead to:

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

Severe, life-threatening, and/or fatal adverse reactions due to drug interactions have been reported in patients treated with PAXLOVID. The most commonly reported concomitant medications resulting in serious adverse reactions were calcineurin inhibitors (e.g., tacrolimus, cyclosporine), followed by calcium channel blockers.

Prior to prescribing PAXLOVID, review all medications taken by the patient to assess potential drug-drug interactions and determine if concomitant medications require a dose adjustment, interruption, and/or additional monitoring (e.g., calcineurin inhibitors) [see Contraindications (4) and Drug Interactions (7)]. See Table 1 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 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 Drug Interactions (7) and Clinical Studies (13)].

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.

Risk of HIV-1 Resistance Development

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 [see Contraindications (4) and Drug Interactions (7)].

Hypersensitivity Reactions

Anaphylaxis, serious skin reactions (including toxic epidermal necrolysis and Stevens-Johnson syndrome), and other hypersensitivity reactions have been reported with PAXLOVID [see Adverse Reactions (6.1)]. If signs and symptoms of a clinically significant hypersensitivity reaction or anaphylaxis occur, immediately discontinue PAXLOVID and initiate appropriate medications and/or supportive care.

Adverse Reactions from Clinical Studies

Adverse Reactions from Clinical Studies
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 (13)]:

• 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.

n 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.

Reporting for Adverse Events

Please visit www.pfizersafetyreporting.com to report or contact us at (852) 2811 9711 as soon as possible.

How to verify your tablets are authentic

PAXLOVID must be prescribed by a licensed healthcare provider and supplied by a government approved pharmacy or medical facility.

Authentic PAXLOVID, from Pfizer Inc., will include the Pfizer name on the label and will be packaged in 5 aluminum push-through blister cards. Individual doses are not for sale. PAXLOVID will be packaged in a rectangular carton. The carton has a colorless, glossy coating that contains a repeated pattern of the Pfizer name and logo all over, and these repeating features are seen in a contrasting matte finish.

PAXLOVID consists of tablets for a 5-day oral treatment regimen, with morning and evening doses.

Pfizer is committed to patient safety and ensuring that people have accurate information about the investigational drug PAXLOVID, including how it is accessed and administered. We are actively monitoring for fraudulent offers of illegitimate PAXLOVID to protect patients from products that might be dangerous and lead to serious and life-threatening harm.

If you suspect the product you have received may be counterfeit, visit www.pfizer.com.hk/en/connect-with-us

Reference: Paxlovid (Nirmatrelvir, Ritonavir) Prescribing Information. Pfizer Corporation Hong Kong Limited Version May 2023