Pronunciation: PREH-vih-miss
Generic name: letermovir
Dosage form: oral tablets, oral pellets, injection for intravenous use
Drug class: Miscellaneous antivirals

Medically reviewed by Carmen Pope, BPharm. Last updated on Sep 5, 2024.

What is Prevymis?

Prevymis (letermovir) is a prescription antiviral medicine that may be used to help prevent cytomegalovirus (CMV) infection and disease in people who have received a stem cell transplant or a kidney transplant and who are at high risk for getting CMV disease.

CMV is a common virus that rarely causes problems in healthy people but can cause serious illness or even death in people with weakened immune systems, especially those who have received an organ transplant or a stem cell transplant.

Prevymis's mechanism of action involves inhibiting the replication of CMV, by blocking the CMV terminase complex which is essential for viral DNA processing and packaging into viral capsids. Prevymis is available in 3 dosage forms: oral tablets, oral pellets, and an injection given through an IV line (intravenously) by a healthcare provider.

Prevymis first gained FDA approval on November 8, 2017.

What is Prevymis used for?

Prevymis is used to prevent CMV infection and disease in adults and children 6 months and older weighing at least 13.2 lb (6 kg) who have received an allogeneic hematopoietic stem cell transplant and who are CMV seropositive.

• An allogeneic hematopoietic stem cell transplant is a procedure in which a patient receives healthy blood-forming cells (stem cells) from a donor. 
• A CMV seropositive person has CMV virus in their blood but may not show any symptoms of infection. They are at risk of "reactivation" of the virus if the immune system becomes weakened.

Prevymis is also used to prevent CMV infection and disease in adults and children aged 12 and older who have received a kidney transplant and are at high risk for getting CMV disease.

• Prevymis may be given when people are CMV seronegative but have received the kidney from a CMV seropositive donor.

It is not known if Prevymis is safe and effective in:

• children under 6 months of age or weighing less than 13.2 lbs (6 kg) who received a hematopoietic stem cell transplant, or
• children under 12 years of age or weighing less than 88.2 lbs (40 kg) who received a kidney transplant. 

Prevymis side effects

The most common Prevymis side effects are:

• nausea, diarrhea, vomiting, stomach pain

• swelling in your arms or legs

• cough

• headache

• feeling tired.

In adult kidney transplant patients receiving Prevymis, the most common side effect was diarrhea.

The side effects of Prevymis in children are similar to the side effects in adults.

Serious side effects and warnings

Prevymis can cause the following serious side effects.

Drug Interactions: Taking Prevymis with certain other medications may cause unexpected side effects or make Prevymis or the other medications work less effectively. Always tell your doctor about all medications you're taking, including over-the-counter drugs and supplements. Your doctor may need to adjust your dosages or monitor you more closely.

Special Concerns for Intravenous (IV) Prevymis: The IV form of Prevymis contains an ingredient called hydroxypropyl betadex which in animal studies has shown the potential to affect hearing. IV Prevymis should only be used in those unable to take the oral form, and should, if possible, not be given for longer than 4 weeks. If you have kidney problems, this ingredient might build up in your body. 

Allergic reactions. Prevymis may cause allergic reactions in some people. Get emergency medical help if you have signs of an allergic reaction to Prevymis which may include hives; difficulty breathing; fast heartbeat, or swelling of your face, lips, tongue, or throat.

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.

Before taking

Some medicines can cause unwanted or dangerous effects when used with Prevymis. Your doctor may need to change your treatment plan if you use any of the following drugs:

• pimozide

• cholesterol medication - pitavastatin, simvastatin

• ergot medicine - dihydroergotamine, ergotamine, ergonovine, methylergonovine.

To make sure Prevymis is safe for you, tell your doctor if you have ever had:

• kidney disease

• liver disease

• diabetes

• high cholesterol or triglycerides (a type of fat in the blood).

It is not known whether Prevymis will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

It is not known whether Prevymis passes into breast milk or if it could affect the nursing baby. Tell your doctor if you are breastfeeding.

How should I use Prevymis?

Prevymis comes as a tablet, oral pellets, or can be given by your healthcare provider through an IV line
(intravenously).

• Use this medicine for the full prescribed length of time, even if you have no symptoms. Skipping doses may increase your risk of further infection that is resistant to medication.

Oral Prevymis

Use Prevymis exactly as prescribed by your doctor. Follow all directions on your prescription label. Do not use this medicine in larger or smaller amounts or for longer than recommended.

Prevymis tablets or pellets are usually given once per day for up to 100 days if you have had a stem cell transplant and for up to 200 days if you have had a kidney transplant.

Prevymis tablets are taken by mouth 1 time a day.

• You may take Prevymis tablets with or without food.
• Do not crush, chew, or break a Prevymis tablet. Swallow the tablet whole.

Prevymis oral pellets are taken 1 time a day. 

• Your healthcare provider will tell you the number of Prevymis oral pellet packets to take for your prescribed
  dose.
• Prevymis oral pellets can be taken by mouth after mixing with soft food or given through a nasogastric tube (NG
  tube) or gastric tube (G tube).
• See the Prevymis Instructions for Use for the right way to prepare and take a dose of Prevymis oral pellets. Keep the Instructions for Use and follow it each time you prepare and take Prevymis oral pellets.
• Do not crush or chew Prevymis oral pellets.

IV Prevymis

Prevymis injection is given as an infusion into a vein.

• Prevymis injection is usually given once a day.
• Prevymis injection must be given slowly, and the infusion can take at least 1 hour to use all of the medicine in the IV bag.
• A healthcare provider will give your first dose and may teach you how to properly use the medication by yourself.
• Prevymis injections are usually given once per day for up to 100 days if you have had a stem cell transplant and for up to 200 days if you have had a kidney transplant.

Prepare an injection only when you are ready to give it. Do not shake the injection solution bottle. Do not use if the medicine looks cloudy, has changed colors, or has particles in it. Call your pharmacist for new medicine.

• Do not give yourself this medicine if you do not understand how to use the injection and properly dispose of needles, IV tubing, and other items used.
• You may need to mix the injection solution with a liquid (diluent) in an IV bag before using it. If you are using the injections at home, be sure you understand how to properly mix and store the medicine.

You can store the mixture for up to 24 hours at room temperature, or up to 48 hours in a refrigerator.

Each single-use vial (bottle) of Prevymis injection is for one use only. Throw it away after one use, even if there is still medicine left inside.

Prevymis dosing information

Prevymis dosing for adults and children 12 years of age and older and weighing at least 30 kg who are HSCT recipients

• Prevymis 480 mg administered once daily orally or as an intravenous (IV) infusion over 1 hour through 100 days post-HSCT.
• In patients at risk for late CMV infection and disease, Prevymis may be continued through 200 days post-HSCT. 

Prevymis dosing for adults and children12 years of age and older and weighing at least 40 kg who are kidney transplant recipients

• Prevymis 480 mg administered once daily orally or as an intravenous (IV) infusion over 1 hour through 200 days post-transplant.

Prevymis dosing for children aged 6 months to less than 12 years of age or 12 years of age and older and weighing less than 30 kg who are HSCT recipients

• Dosing is based on weight.
• Prevymis is administered once daily orally or as an IV infusion over 1 hour through 100 days post-HSCT.
• In patients at risk for late CMV infection and disease, Prevymis may be continued through 200 days post-HSCT. 

Related/similar drugs

valacyclovir, valganciclovir, Valcyte, letermovir, Cytovene

What happens if I miss a dose?

Use the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not use extra medicine to make up for the missed dose.

What happens if I overdose?

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

What should I avoid while using Prevymis?

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

What other drugs will affect Prevymis?

Sometimes it is not safe to use certain medications at the same time. Some drugs can affect your blood levels of other drugs you take, which may increase side effects or make the medications less effective. Tell your doctor about all your current medicines and any you start or stop using.

Especially tell your doctor if you take pimozide or ergot alkaloids because you should not take Prevymis with these.

If you are taking Prevymis with cyclosporine then you should not take pitavastatin or simvastatin.

This is not a complete list of interactions. See the Prevymis Package Insert for a complete list. 

Prevymis ingredients

Active ingredient: letermovir

Inactive ingredients:

• Tablets: colloidal silicon dioxide, croscarmellose sodium, magnesium stearate, microcrystalline cellulose, and povidone 25.
• Film coating: hypromellose 2910, iron oxide red (only for 480 mg tablets), iron oxide yellow, lactose monohydrate, titanium dioxide, and triacetin. Carnauba wax is added as a polishing agent.
• Oral Pellets: colloidal silicon dioxide, croscarmellose sodium, magnesium stearate, microcrystalline cellulose, and povidone K-29/32.
• Film coating: hypromellose 2910, iron oxide red, iron oxide yellow, lactose monohydrate, titanium dioxide, and triacetin.
• Injection: hydroxypropyl betadex, sodium chloride, sodium hydroxide, and Water for Injection.

Prevymis storage

Store Prevymis tablets, Prevymis oral pellets, and Prevymis injection at room temperature between 68°F to
77°F (20°C to 25°C).

• Store the tablets in their original package until you are ready to take them to protect them from moisture.
• Store the oral pellets in their original packet until you are ready to take them.
• Store the injection in the original carton to protect it from exposure to light.

Who makes Prevymis?

Merck Sharp & Dohme LLC makes Prevymis.

Frequently asked questions

• What is Prevymis used to treat?

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer