• Prevention of cytomegalovirus (CMV) infection and disease in adult CMV-seropositive recipients of an allogeneic hematopoietic stem cell transplant (HSCT).

Contraindicated in:

• Concurrent use of pimozide or ergot alkaloids
• Concurrent use of pitavastatin and simvastatin when administered with cyclosporine
• Severe hepatic impairment.

Use Cautiously in:

• Renal impairment (CCr <50 mL/min; accumulation of IV vehicle may occur [closely monitor serum creatinine])
• OB: Lactation: Safety not established in pregnancy or lactation
• Pedi: Safety and effectiveness not established in children.

CV: peripheral edema, atrial fibrillation, tachycardia.

GI: abdominal pain, diarrhea, nausea, vomiting.

GU: ↑serum creatinine.

Hemat: anemia, neutropenia, thrombocytopenia.

Neuro: headache.

Resp: cough.
Misc: fatigue.

Drug-Drug:

• Letermovir is a substrate of organic anion-transporting polypeptide 1B1/3 (OATP1B1/3) transporters, P-glycoprotein, and UDP-glucuronosyltransferase 1A1/3 (UGT1A1/3) enzymes. It is also a moderate inhibitor of CYP3A and an inhibitor of OATP1B1/3 transporters.
• May ↑ pimozide concentrations which may ↑ risk of torsades de pointes; concurrent use contraindicated.
• May ↑ ergotamine and dihydroergotamine concentrations which may ↑ risk of ergotism; concurrent use contraindicated.
• May significantly ↑ pitavastatin and simvastatin concentrations when concurrently administered with cyclosporine, which may ↑ risk of myopathy and rhabdomyolysis; concurrent use contraindicated.
• May ↑ amiodarone levels and risk of toxicity; closely monitor amiodarone concentrations.
• May ↓ warfarin levels and ↑ the risk for a thromboembolic event; closely monitor INR.
• May ↓ phenytoin levels; concurrent use not recommended.
• May ↑ glyburide, repaglinide, and pioglitazone levels; closely monitor blood glucose levels; when used concurrently with cyclosporine, avoid use with repaglinide.
• May ↓ voriconazole levels and ↑ risk of therapeutic failure; closely monitor for reduced effectiveness.
• Bosentan, carbamazepine, efavirenz, etravirine, modafinil, nafcillin, nevirapine, phenobarbital, phenytoin, rifabutin, rifampin, and thioridazine may ↓ levels and ↑ risk of therapeutic failure; concurrent use not recommended.
• May ↑ atorvastatin levels; do not exceed atorvastatin dose of 20 mg/day; when used concurrently with cyclosporine, avoid use with atorvastatin.
• May ↑ pitavastatin and simvastatin levels; concurrent use not recommended.
• May ↑ fluvastatin, lovastatin, pravastatin, and rosuvastatin levels; consider ↓ dose of statin; when used concurrently with cyclosporine, avoid use with lovastatin.
• Concurrent use with cyclosporine↑ both cyclosporine and letermovir levels; ↓ dose of letermovir and closely monitor whole blood concentrations of cyclosporine.
• May ↑ sirolimus and tacrolimus levels; closely monitor whole blood concentrations of sirolimus and tacrolimus.
• May ↓ omeprazole and pantoprazole levels; closely monitor.

Drug-Natural Products:

• St. John's wort may ↓ levels and ↑ risk of therapeutic failure; concurrent use not recommended.

• Solution for injection: 20 mg/mL;
• Tablets: 240 mg; 480 mg;

IV therapy should only be used when patients are unable to take oral therapy.

• IV, PO (Adults): 480 mg once daily started between Day 0 and Day 28 post-transplantation and continued through Day 100 post-transplantation. Concurrent use with cyclosporine — 240 mg once daily started between Day 0 and Day 28 post-transplantation and continued through Day 100 post-transplantation.

Prevymis

• Prevents viral DNA processing and packaging by inhibiting the CMV DNA terminase complex.

• Preventing of clinically significant CMV infection following transplant.

Therapeutic Classification: antivirals

Absorption: 35% absorbed following oral administration (↑ when cyclosporine given); IV administration results in complete bioavailability.

Distribution: Widely distributed.

Protein Binding: 99%.

Metabolism/Excretion: Primarily metabolized in liver via UGT1A1/UGT1A3; 93% excreted in feces (70% as unchanged drug); <2% excreted in urine.

Half-life: 12 hr.

(plasma concentrations)

• Instruct patient to take letermovir as directed for full course of therapy. Take missed doses as soon as remembered on day of dose; do not take more than 1/day. If remembered next day, skip previous dose and resume schedule; do not double doses.
• Instruct patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult health care professional before taking other Rx, OTC, herbal products.
• Advise female patients to notify health care professional if pregnancy is planned or suspected or if breast feeding.

le-TERM-oh-vir