Comprehensive medication guide to Prevymis including estimated pricing, availability information, side effects, and how to find it in stock at your local pharmacy.
Estimated Insurance Pricing
With commercial insurance and Merck's savings card, eligible patients may pay as little as $15 per prescription (up to 8 qualifying fills). Medicare Part D covers Prevymis on a specialty tier; the $2,000 annual out-of-pocket cap (2025+) provides significant protection. Prior authorization is required by most commercial and Medicare Part D plans.
Estimated Cash Pricing
Prevymis has a retail price of approximately $8,700–$9,053 per 30-day supply of 480 mg tablets (brand only; no generic available). With a GoodRx coupon, the price drops to approximately $7,774, and with SingleCare to roughly $7,704.
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Prevymis is the brand name for letermovir, an antiviral medication manufactured by Merck. First approved by the FDA on November 8, 2017, Prevymis belongs to a novel class of antivirals called CMV DNA terminase complex inhibitors — the first new class of CMV antivirals in decades. It works through a completely different mechanism than older antivirals like ganciclovir and valganciclovir.
Prevymis is FDA-approved for the prophylaxis (prevention) of cytomegalovirus (CMV) infection and disease in two patient populations: CMV-seropositive (R+) recipients of allogeneic hematopoietic stem cell transplants (HSCT), and high-risk (D+/R-) kidney transplant recipients. It is available as 240 mg and 480 mg oral tablets, 20 mg and 120 mg oral pellet packets (for children or patients who cannot swallow tablets), and 240 mg and 480 mg IV injection vials for hospitalized patients.
CMV is a common herpesvirus that stays dormant in healthy people but can reactivate dangerously in immunocompromised transplant patients. Without prophylaxis, CMV can cause pneumonia, hepatitis, retinitis (leading to blindness), gastrointestinal disease, and is associated with increased mortality in HSCT recipients. Prevymis significantly reduces this risk when taken as prescribed.
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Prevymis works by inhibiting the CMV DNA terminase complex — specifically the pUL56 subunit. The terminase complex is a specialized viral machinery responsible for cutting and packaging newly copied viral DNA into viral capsids (protein shells) during the final stages of virus assembly. Without a functional terminase complex, new infectious viral particles cannot be formed, preventing the virus from spreading.
This mechanism is fundamentally different from older antivirals like ganciclovir, which block DNA polymerase (the enzyme that copies viral DNA). Because the CMV terminase complex has no equivalent in human cells, letermovir is highly CMV-specific and causes significantly fewer bone marrow side effects. In head-to-head trials, leukopenia (low white blood cell counts) occurred in only 26% of letermovir patients compared to 64% of valganciclovir patients.
Additionally, because letermovir and ganciclovir act through different mechanisms, there is no cross-resistance between them. A CMV strain resistant to ganciclovir (through UL97 or UL54 mutations) remains fully susceptible to letermovir. This makes Prevymis a valuable option even in patients with ganciclovir-resistant CMV.
480 mg — tablet
Standard once-daily dose for most adult patients; taken with or without food
240 mg — tablet
Once-daily dose when co-administered with cyclosporine
120 mg — oral pellets
Oral pellet packet; for pediatric patients 15–<30 kg or as alternative to tablets
480 mg/24 mL — IV injection
Intravenous infusion over 1 hour; for patients unable to take oral therapy
240 mg/12 mL — IV injection
IV formulation for patients on cyclosporine or smaller body weight
Prevymis is not listed on the FDA's official drug shortage database, meaning there is no national manufacturing shortage. However, many transplant patients struggle to fill their prescriptions at standard retail pharmacies because Prevymis is a specialty medication distributed almost exclusively through specialty pharmacy channels. Its retail price of approximately $8,700–$9,053 per 30-day supply makes it impractical for most retail pharmacies to stock, as low local demand means the drug sits on shelves tying up significant capital.
Prevymis is typically dispensed through specialty pharmacies such as Accredo, CVS Specialty, Walgreens Specialty, or Optum Specialty. Most transplant centers have established specialty pharmacy relationships and can arrange dispensing before or at discharge. Insurance prior authorization is required by most plans and can take 24-72 hours, so starting the process early is critical.
If you are having trouble finding a pharmacy that carries Prevymis, medfinder can contact pharmacies near you by phone to find which ones have it available, texting you the results. This is far more reliable than online searches for specialty drugs.
Prevymis is not a controlled substance and has no DEA prescribing restrictions. However, because it is prescribed specifically for post-transplant CMV prophylaxis, it is typically prescribed by physicians with specialized expertise in transplant medicine or infectious disease. Most insurance prior authorization criteria require it to be prescribed by a qualifying specialist.
Telehealth is generally not the primary channel for initiating Prevymis — it is tied to post-transplant care at specialized transplant centers. However, some transplant programs offer telehealth follow-up visits for established patients, which may include Prevymis prescription renewals. Check with your transplant center about telehealth capabilities.
No. Prevymis (letermovir) is not a controlled substance. It is not classified under any DEA schedule (Schedule I through V). There are no special restrictions on how Prevymis can be prescribed, dispensed, or refilled from a controlled substance standpoint. Your doctor can prescribe Prevymis without DEA-specific limitations, and pharmacies can dispense it without controlled substance reporting requirements.
However, Prevymis does require a valid prescription from a licensed healthcare provider — it is not available over the counter. Most insurance plans also require prior authorization before covering it. The primary access barriers to Prevymis are its specialty pharmacy distribution model, high cost, and insurance prior authorization requirements — not DEA scheduling.
The most common side effects of Prevymis (occurring in ≥10% of patients in clinical trials):
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Valganciclovir (Valcyte)
Most common alternative; oral prodrug of ganciclovir; standard of care before letermovir approval; causes more bone marrow suppression (leukopenia 64% vs 26%); generic available at significantly lower cost; requires renal dose adjustment
Ganciclovir
IV antiviral; parent compound of valganciclovir; for hospitalized patients unable to take oral medications; significant myelosuppression and nephrotoxicity; no oral formulation
Valacyclovir (Valtrex)
High-dose oral option; less effective than ganciclovir-class drugs for CMV; used when myelosuppression is a concern; less potent CMV prophylaxis
Foscarnet
IV antiviral reserved for ganciclovir-resistant CMV or when other agents are contraindicated; significant nephrotoxicity limits use; last-resort option not typically used for prophylaxis
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Pimozide (Orap)
majorContraindicated. Letermovir inhibits CYP3A, raising pimozide levels and causing potentially fatal QT prolongation and torsades de pointes.
Ergot alkaloids (ergotamine, dihydroergotamine)
majorContraindicated. CYP3A inhibition by letermovir raises ergot levels, causing ergotism — severe vasoconstriction that can lead to stroke or limb ischemia.
Pitavastatin / Simvastatin (with cyclosporine)
majorContraindicated when co-administered with cyclosporine. Combined inhibition of OATP1B1/3 by letermovir and cyclosporine dramatically raises statin levels, causing myopathy or rhabdomyolysis.
Cyclosporine
moderateCyclosporine increases letermovir levels approximately 2-fold via OATP1B1/3 inhibition. Reduce Prevymis dose to 240 mg once daily when co-administered. Monitor cyclosporine levels closely.
Tacrolimus (Prograf)
moderateLetermovir inhibits OATP1B1/3 transporters, potentially increasing tacrolimus levels. Close tacrolimus level monitoring with appropriate dose adjustments is required.
Warfarin
moderateLetermovir may increase warfarin levels through CYP enzyme effects, raising bleeding risk. Monitor INR closely when starting or stopping Prevymis.
Voriconazole (Vfend)
moderateLetermovir induces CYP2C9/CYP2C19 and REDUCES voriconazole levels, potentially making it ineffective. Monitor voriconazole levels when co-administering.
Rifampin
majorRifampin dramatically reduces letermovir blood levels by inducing drug metabolism. Co-administration is not recommended.
St. John's Wort
moderateThis herbal supplement reduces letermovir levels. Avoid all St. John's Wort products while taking Prevymis.
Phenytoin / Carbamazepine / Phenobarbital
moderateThese antiepileptic drugs can reduce letermovir blood levels, potentially reducing Prevymis effectiveness. Use with caution and monitor clinical response.
Prevymis (letermovir) represents a genuine advance in CMV prevention for transplant patients. Its novel mechanism — targeting the CMV DNA terminase complex rather than DNA polymerase — gives it a superior safety profile over older antivirals, with dramatically less bone marrow suppression. Combined with once-daily dosing and no renal dose adjustment needed for oral therapy, it has become a preferred option in both HSCT and high-risk kidney transplant settings.
The primary challenges with Prevymis are its high cost (approximately $8,700–$9,053 retail per month) and its specialty pharmacy distribution model, which means it's not available at every corner drugstore. However, Merck's savings programs can reduce out-of-pocket costs to as little as $15 per prescription for commercially insured patients. For patients who cannot access it easily, having a plan in place before discharge — including prior authorization and specialty pharmacy enrollment — is essential.
If you are having difficulty locating Prevymis at a pharmacy near you, medfinder can contact local pharmacies on your behalf to find which ones can fill your prescription — saving you hours of frustrating phone calls during what is already a challenging time.
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Our medication guides are researched and written to help patients make informed decisions. All content is reviewed for accuracy and updated regularly. Learn more about our standards
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