Paxlovid

Paxlovid is an antiviral treatment used for COVID-19 to lower the risk of severe COVID-19, including hospitalization or death. Paxlovid works by helping stop the virus from multiplying, which improves COVID-19 symptoms and reduces hospitalizations and deaths in high-risk patients.

Paxlovid contains nirmatrelvir tablets and ritonavir tablets packaged together.

Paxlovid should be started as soon as possible after a COVID-19 diagnosis and within the first 5 days that you have had symptoms.

The usual Paxlovid dose is two nirmatrelvir tablets and one ritonavir tablet taken together twice daily for 5 days. The dose needs to be changed if you have kidney problems, and if you are taking certain medicines, Paxlovid is not suitable for some patients.

Paxlovid is used for mild-to-moderate COVID-19 in patients who are at high risk of severe COVID-19, including hospitalization or death. It is available under:

• FDA approval for adults
• Emergency Use Authorisation (EUA) patients 12 to 18 years old.

People who are at high risk of severe COVID-19 are patients with:

• heart disease, diabetes, lung disease, cancer, blood disorders, immune disorders, mental health conditions, disabilities, or other conditions
• being overweight or obese
• 50 years or older
• lifestyle factors, such as smoking
• physical, mental, and developmental disabilities.

Paxlovid is not approved for use as a pre-exposure or post-exposure prophylaxis to prevent COVID-19 or for the prevention of long COVID.

Paxlovid’s active ingredient nirmatrelvir, works by blocking an enzyme (SARS-CoV-2-3CL protease) that the coronavirus needs to replicate. Ritonavir works by increasing the concentration of nirmatrelvir in the body, making nirmatrelvir a more effective antiviral.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Paxlovid Instructions

Take nirmatrelvir together with ritonavir (two tablets of nirmatrelvir and one tablet of ritonavir) twice a day for 5 consecutive days. Take your doses at around the same time each day. If you have kidney disease, talk to your healthcare provider, as you may need to take a different dose.

Take tablets as soon as possible after diagnosis of COVID-19 and within 5 days of when symptoms first appear.

You may take tablets with or without food.

Swallow the tablets whole and do not crush, chew, or break them.

General Information

You may need frequent blood tests to check your liver function.

If you are taking a ritonavir- or cobicistat-containing medicine to treat hepatitis C or Human Immunodeficiency Virus (HIV), you should continue to take your medicine as prescribed by your healthcare provider.

Talk to your healthcare provider if you do not feel better or if you feel worse after 5 days.

If you have kidney disease, your prescriber may prescribe you a lower dose. Talk to your healthcare provider to make sure you receive the correct Dose Pack.

Paxlovid Drug Interactions: Paxlovid can interact with other medicines, causing severe or life-threatening side effects or death. It is important to know the medicines that should not be taken with this medicine. See the Interactions section below and check the interactions checker.

Hypersensitivity Reactions: Anaphylaxis, serious skin reactions (including toxic epidermal necrolysis and Stevens-Johnson syndrome), and other hypersensitivity reactions have been reported with this medicine. Do not take this medicine if you are allergic to nirmatrelvir, ritonavir, or any of the ingredients in this medicine. If signs and symptoms of a clinically significant hypersensitivity reaction or anaphylaxis occur, immediately stop taking the tablets and start appropriate medications and/or supportive care.

Hepatotoxicity: Hepatic transaminase elevations, clinical hepatitis, and jaundice have occurred in patients receiving ritonavir, one of the active ingredients in Paxlovid.

HIV-1 Drug Resistance: Using Paxovid may lead to a risk of HIV-1 developing resistance to HIV protease inhibitors if you have uncontrolled or undiagnosed HIV-1 infection.

COVID rebound is when COVID symptoms return between 2 and 8 days after finishing treatment; symptoms are mild, transient, and usually clear up in 1 to 3 days. COVID rebound can happen in those who are vaccinated, unvaccinated, treated, and not treated. When COVID-19 symptoms return in Paxlovid-treated patients, some people have called it Paxlovid rebound.

The CDC states that “There is currently no evidence that additional treatment is needed with Paxlovid or other anti-SARS-CoV-2 therapies in cases where COVID-19 rebound is suspected.”

You should not use this medicine if you are allergic to the active ingredients nirmatrelvir and ritonavir or any of the inactive ingredients. A list of ingredients is at the bottom of this page.

Tell your doctor if:

• you have liver problems or a liver disease such as hepatitis;
• you have kidney problems;
• you have an HIV-1 infection;
• you are pregnant or breastfeeding; or
• you have any serious or chronic disease.

Tell your doctor about all other medicines you use, including prescription and over-the-counter medicines, vitamins, and herbal products. Paxlovid can interact with other medicines, causing severe or life-threatening side effects or death. See the Interactions section below.

Pregnancy

Tell your healthcare provider right away if you are or if you become pregnant. It is not known if this medicine can harm your unborn baby. Ritonavir can make birth control pills or birth control skin patches less effective. Ask your doctor about other birth control options such as an injection, implant, vaginal ring, condom, diaphragm, cervical cap, or contraceptive sponge.

Breastfeeding

Tell your healthcare provider you are breastfeeding or plan to breastfeed. It is not known if Paxlovid can pass into your breast milk. Talk to your healthcare provider about the best way to feed your baby during treatment with this medicine.

Common Paxlovid side effects

• changes in your sense of taste; or
• diarrhea

Serious side effects

This medicine may cause serious side effects, including allergic reactions, hypersensitivity reactions, and liver problems.

Allergic reactions: Get emergency medical help if you have signs of an allergic reaction (hives, difficulty breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Liver problems: Call your doctor at once if you have:

• Liver problems symptoms include loss of appetite, stomach pain (upper right side), tiredness, itching, dark urine, clay-colored stools, and jaundice (yellowing of the skin or eyes).

Ritonavir side effects

Ritonavir, one of the active ingredients in this medicine affects your immune system, which may cause certain side effects (even weeks or months after you've taken nirmatrelvir and ritonavir). Tell your doctor if you have:

• signs of a new infection--fever, night sweats, swollen glands, cold sores, cough, wheezing, diarrhea, weight loss;
• trouble speaking or swallowing, problems with balance or eye movement, weakness or prickly feeling; or
• swelling in your neck or throat (enlarged thyroid), menstrual changes, impotence.

This is not a complete list of side effects, and others may occur. Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Usual Paxlovid Dosing for Adult COVID-19 (FDA-approved)

Nirmatrelvir: 300 mg orally twice a day for 5 daysRitonavir: 100 mg orally twice a day for 5 days

Usual Paxlovid Dosing for 12 to 18-Year-Old COVID-19 (EUA)

For investigational use onlyUse: Patients 12 to 18 years old weighing at least 40 kgNirmatrelvir: 300 mg orally twice a day for 5 daysRitonavir: 100 mg orally twice a day for 5 days

Usual Dosing for Renal Impairment

Mild renal impairment [estimated glomerular filtration rate (eGFR) ≥60 to <90 mL/min]. No dosage adjustment is recommended

Moderate renal impairment (eGFR ≥30 to <60 mlmin)Nirmatrelvir: 150 mg twice daily for 5 daysRitonavir: 100 mg twice daily for 5 days

Severe renal impairment (eGFR <30 mlmin), including those requiring hemodialysisDay 1: 300 mg nirmatrelvir (two 150 mg tablets) with 100 mg ritonavir (one 100 mg tablet) once Day 2 - 5: 150 mg nirmatrelvir (one 150 mg tablet) with 100 mg ritonavir (one 100 mg tablet) once daily. On days of hemodialysis, take your dose after receiving hemodialysis.

General dosing information:

• If you have kidney disease, your healthcare provider may prescribe a lower dose. Talk to your healthcare provider to make sure you receive the correct Dose Pack.
• Nirmatrelvir must be coadministered with ritonavir. Prescriptions should specify the numeric dose of each active component within this product.
• This product should be started as soon as possible after COVID-19 has been diagnosed and within 5 days of symptom onset.
• If hospitalization is required due to severe/critical COVID-19 after starting treatment with this product, the patient should complete the full 5-day treatment course per the health care provider's discretion.

If you miss a dose of your tablets within 8 hours of the time it is usually taken, take it as soon as you remember. If you miss a dose by more than 8 hours, skip the missed dose and take the next dose at your regular time. Do not take 2 doses of Paxlovid at the same time.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Many drugs can affect Paxlovid, and some drugs should not be used at the same time. Paxlovid can interact with other medicines causing severe or life-threatening side effects or death. Tell your doctor about all other medicines you use. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here.

Do not take Paxlovid with any of these medicines:

• sildenafil (Revatio) when used to treat pulmonary arterial hypertension (PAH);
• lumacaftor, ivacaftor;
• bosentan;
• alfuzosin, colchicine;
• tolvaptan;
• Naloxegol;
• finerenone;
• Flibanserin;
• lomitapide;
• Voclosporin;
• rifampin, rifapentine;
• St. John's Wort;
• heart medicine - ivabradine, amiodarone, eplerenone, dronedarone, flecainide, propafenone, quinidine, ranolazine;
• prostate medicine - silodosin;
• antipsychotic medicine - lurasidone, pimozide;
• ergot medicines - dihydroergotamine, ergotamine, methylergonovine;
• migraine headache medicine - eletriptan, ubrogepant;
• cholesterol-lowering medicine - lovastatin, simvastatin;
• a sedative - triazolam, oral midazolam;
• a cancer medicine - apalutamide, enzalutamide; or
• seizure medicine - primidone, carbamazepine, phenobarbital, phenytoin
• suzetrigine.

Not all possible interactions are listed in this medication guide.

Store at room temperature 20°C to 25°C (68°F to 77°F).

Paxlovid Pfizer Labs, Division of Pfizer Inc. New York, NY 10001.

Nirmatrelvir 150 mg tablets

Active ingredient: nirmatrelvirInactive 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.

Ritonavir 100 mg tablets

Active ingredient: ritonavirInactive ingredients: anhydrous dibasic calcium phosphate, colloidal silicon dioxide, copovidone, sodium stearyl fumarate, and sorbitan monolaurate. The following are the ingredients in the film coating: colloidal silicon dioxide, hydroxypropyl cellulose, hypromellose, polyethylene glycol 400, polyethylene glycol 3350, polysorbate 80, talc, and titanium dioxide.