Nirmatrelvir and Ritonavir

Brand Name(s): Paxlovid®

Why is this medicine prescribed?

The combination of nirmatrelvir and ritonavir is used to treat coronavirus disease 2019 (COVID-19 infection) caused by the SARS-CoV-2 virus in adults who have mild to moderate symptoms and are at risk of severe disease that could result in hospitalization or death. The FDA has also issued an emergency use authorization (EUA) authorizing use of nirmatrelvir and ritonavir to treat coronavirus disease 2019 (COVID-19 infection) caused by the SARS-CoV-2 virus in children 12 years of age and older who weigh at least 88 pounds (40 kg). Nirmatrelvir is in a class of medications called antivirals. It works by stopping the virus from spreading in the body. Ritonavir is in a class of medications called pharmacokinetic boosters. It works by increasing the amount of nirmatrelvir available in the body so that the medication will have a greater effect.

How should this medicine be used?

The combination of nirmatrelvir and ritonavir comes as tablets to be taken by mouth. The nirmatrelvir and ritonavir must be taken together for the medication to work correctly. It is usually taken with or without food two times a day for 5 days. Take nirmatrelvir and ritonavir at around the same times every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take nirmatrelvir and ritonavir exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Swallow the tablets whole; do not split, chew, or crush them.

Take nirmatrelvir and ritonavir until you finish the prescription, even if you start to feel better. Do not stop taking nirmatrelvir and ritonavir without talking to your doctor. If you stop taking nirmatrelvir and ritonavir too soon or skip doses, your infection may not be completely treated.

Ask your pharmacist or doctor for a copy of the manufacturer's information for the patient.

What special precautions should I follow?

Before taking nirmatrelvir and ritonavir,

  • tell your doctor and pharmacist if you are allergic to nirmatrelvir, ritonavir, any other medications, or any of the ingredients in nirmatrelvir or ritonavir tablets. Ask your pharmacist for a list of the ingredients.
  • Some medications should not be taken with nirmatrelvir and ritonavir. Other medications may cause dosing changes or extra monitoring when taken with nirmatrelvir and ritonavir. Make sure you have discussed any medications you are currently taking or plan to take before starting nirmatrelvir and ritonavir with your doctor and pharmacist. Before starting, stopping, or changing any medications while taking nirmatrelvir and ritonavir, please get the advice of your doctor or pharmacist.
  • If you are taking a ritonavir- or cobicistat-containing medicine to treat hepatitis C or human immunodeficiency virus (HIV), you should continue to take these medications as prescribed while taking nirmatrelvir and ritonavir.
  • tell your doctor if you have or have ever had HIV, kidney disease, or liver disease.
  • Tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking nirmatrelvir and ritonavir, call your doctor.
  • you should know that nirmatrelvir and ritonavir may decrease the effectiveness of hormonal contraceptives (birth control pills, patches, rings, implants, injections, and intrauterine devices). Use another form of birth control or do not have sexual intercourse while you are taking nirmatrelvir and ritonavir. Talk to your doctor about types of birth control that will work for you during your treatment with nirmatrelvir and ritonavir.

What special dietary instructions should I follow?

Unless your doctor tells you otherwise, continue your normal diet.

What should I do if I forget to take a dose?

If you miss a dose within 8 hours of the time it is usually taken, take the missed dose as soon as you remember it. However, if you miss a dose by more than 8 hours, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

What should I do in case of overdose?

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at . If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

What side effects can this medicine cause?

Nirmatrelvir and ritonavir may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • headache
  • nausea or vomiting
  • general ill feeling
  • abdominal pain
  • altered taste
  • diarrhea
  • muscle aches

Some side effects can be serious. If you experience any of these symptoms, stop taking nirmatrelvir and ritonavir and call your doctor immediately:

  • rash, redness of skin, itching
  • difficulty breathing or shortness of breath
  • swelling of tongue, lips or mouth
  • loss of appetite
  • yellowing of your skin or the whites of your eyes
  • dark-colored urine
  • pale-colored stools

Nirmatrelvir and ritonavir may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online ( ) or by phone (1-800-332-1088).

What should I know about storage and disposal of this medication?

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach.

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website ( ) for more information if you do not have access to a take-back program.

What other information should I know?

Keep all appointments with your doctor.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

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

You should continue to isolate as directed by your doctor and follow public health practices such as wearing a mask, social distancing, and frequent hand washing.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

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