Prevymis

(Letermovir)

The active ingredient in Prevymis is letermovir. Prevymis works by preventing cytomegalovirus (CMV) infection from multiplying in the body, particularly in people who have had a stem cell transplant. It blocks the CMV DNA terminase complex, an enzyme the virus needs to package its DNA and produce new infectious virus particles. Without this step, the virus cannot replicate effectively, helping prevent CMV infection and related complications.

Follow all directions given to you by your doctor and read all documents provided, including the full Prescribing Information, FDA-Approved Product Labeling, Instructions for Use, and Medication Guide before using Prevymis. However, the following is a synopsis of the general guidelines for the use of Prevymis:

• Prevymis tablets, oral pellets, and injection are taken once daily, with or without food.
• Oral pellets should be mixed with soft food or liquid as directed and swallowed without chewing.
• Do not crush or split tablets unless instructed by a healthcare professional.
• Treatment is usually started within the first few weeks after transplant.
• Continue taking Prevymis for the full prescribed duration, even if you feel well.
• Dose adjustment may be required for patients with renal impairment when taken with cyclosporine.
• If you miss a dose, take it as soon as you remember, unless it is close to the next dose. Do not take two doses at once.
• Keep all follow-up appointments so your healthcare provider can monitor for CMV reactivation and adverse reactions.
• If Prevymis is co-administered with cyclosporine in pediatric HSCT patients less than 12 years of age, dose adjustment may be required.

Some mild or common side effects of Prevymis seen in clinical trials as compared to placebo include:

• Nausea.
• Diarrhea.
• Vomiting.
• Headache.
• Cough.
• Fatigue.
• Abdominal pain.

Some individuals may experience serious side effects while using Prevymis. These side effects may require immediate medical attention. If you experience any of the following, contact your healthcare provider or seek emergency medical help:

• Signs of an allergic reaction, such as rash, hives, swelling, or trouble breathing.
• Significant changes in liver function tests.
• Severe or persistent gastrointestinal symptoms.
• New or worsening symptoms that may suggest CMV reactivation.
• Prevymis injection contains an ingredient called hydroxypropyl betadex, which in animal studies has shown the potential to affect hearing.

These are not all of the possible side effects of $Drugname. You should always seek medical advice from your healthcare provider for any questions or concerns about your medical condition or treatment. Read all patient information, medication guides, or drug information sheets that come with this medication. You can also report adverse effects to the Food and Drug Administration at www.fda.gov/medwatch or 1-800-FDA-1088.

Before starting Prevymis, it is crucial to discuss any existing health conditions with your healthcare provider. You should be sure that your healthcare provider is aware of all your medical conditions, including:

• Liver disease or hepatic impairment.
• Kidney disease or renal impairment.
• A history of drug interactions or medication sensitivities.
• A history of CMV infection or reactivation.
• Any planned changes to immunosuppressive therapy.
• Pregnancy or plans to become pregnant.
• Breastfeeding or plans to breastfeed.

Prevymis is contraindicated in patients taking certain medications due to serious drug interactions. These include pimozide and ergot alkaloids such as ergotamine and dihydroergotamine. Prevymis should also not be used with specific statins at certain doses when taken with cyclosporine.

Prevymis begins working shortly after starting therapy by reducing the risk of CMV replication. It does not produce noticeable symptom relief because it is used for prevention. Effectiveness is assessed through laboratory monitoring and the reduced incidence of CMV infection during the treatment period.

When Prevymis is taken with other prescription drugs, over-the-counter medications, vitamins, and supplements, it may change how they work or increase the frequency or severity of side effects. Make sure that you tell your healthcare professional about anything that you are taking to avoid any negative drug interactions, including:

• Cyclosporine, which increases lopinavir levels and requires dose adjustment.
• Statins such as atorvastatin, simvastatin, rosuvastatin, fluvastatin, and pitavastatin, which may increase the risk of muscle toxicity.
• Ergot alkaloids, including ergotamine and dihydroergotamine, are contraindicated due to the risk of severe vasospasm.
• Pimozide, due to the risk of serious heart rhythm problems.
• Rifampin, carbamazepine, phenytoin, and St. John’s wort may reduce Prevymis effectiveness.
• Efavirenz and nevirapine, which may decrease letermovir levels.
• Amiodarone and bosentan may increase the risk of side effects.
• Voriconazole, which may have altered exposure when used together.
• Valganciclovir.
• Modafinil.

Prevymis is available in the following dosage forms:

Oral tablets.

Oral pellets.

Intravenous injection.

The standard adult dose is once daily, with specific dose adjustments based on transplant type, renal impairment, and use of cyclosporine.

It should be stored at room temperature, away from the reach of children or pets.

Prevymis is manufactured by Merck Sharp & Dohme, a subsidiary of Merck & Co., Inc.

No, Prevymis is currently only available as a brand-name prescription drug.

Do not stop taking Prevymis without speaking to your healthcare provider. Stopping early may increase the risk of CMV infection. Your provider will determine when it is safe to discontinue therapy based on transplant type and clinical status.

There are limited data on the use of Prevymis during pregnancy. Effective contraception is recommended during treatment and for at least one week after the last dose. Discuss risks and benefits with your healthcare provider.

It is not known if the medication is found in breast milk. However, breastfeeding is not recommended during treatment with Prevymis and for at least one week after the final dose due to the potential for adverse reactions in the breastfed infant. Discuss alternative feeding options with your healthcare provider.