Home Drug Guide Letermovir

Drug Guide

Generic Name

Letermovir

Brand Names Prevymis

Classification

Therapeutic: Antiviral, Antiviral for CMV infection

Pharmacological: DNA terminase complex inhibitor

FDA Approved Indications

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

Mechanism of Action

Inhibits the terminase complex of CMV, preventing viral DNA processing and packaging, thus inhibiting viral replication.

Dosage and Administration

Adult: 480 mg orally once daily, starting within 28 days after transplant, continued up to 100 days or until immunosuppressive therapy is discontinued.

Pediatric: Not indicated for pediatric use.

Geriatric: No specific dosage adjustment; consult clinical judgment.

Renal Impairment: No adjustment recommended for mild or moderate impairment; with severe impairment, use caution and monitor.

Hepatic Impairment: No specific dosage adjustment needed; use with caution and monitor closely.

Pharmacokinetics

Absorption: Rapid after oral administration with approximately 80% bioavailability.

Distribution: Extensively bound to plasma proteins.

Metabolism: Primarily metabolized via CYP3A4 and UGT1A1 pathways.

Excretion: Excreted mainly via feces, with minimal renal clearance.

Half Life: 12 hours.

Contraindications

  • Hypersensitivity to letermovir or any component of the formulation.

Precautions

  • Use with caution in patients with concomitant medications that prolong QT interval or are metabolized by CYP3A4. Regular monitoring of ECG is advised in at-risk populations.

Adverse Reactions - Common

  • Gastrointestinal symptoms (nausea, diarrhea, constipation) (Uncommon to common)
  • Headache (Uncommon)

Adverse Reactions - Serious

  • Arrhythmias, including QT prolongation (Rare)
  • Hepatotoxicity (Rare)

Drug-Drug Interactions

  • CYP3A4 inhibitors (e.g., ketoconazole, ritonavir) increase letermovir levels; CYP3A4 inducers (e.g., rifampin) decrease levels.

Drug-Food Interactions

  • None significant.

Drug-Herb Interactions

  • St. John’s Wort may induce CYP3A4 and reduce efficacy.

Nursing Implications

Assessment: Monitor for signs of CMV replication, assess liver function tests, monitor ECG in patients on QT-prolonging drugs.

Diagnoses:

  • Risk for infection due to immunosuppression.

Implementation: Administer as prescribed, ensure adherence, monitor for side effects.

Evaluation: Efficacy assessed by monitoring CMV viral load; side effects observed and reported.

Patient/Family Teaching

  • Inform about the importance of adherence to medication schedule.
  • Report any signs of infection, liver problems, or arrhythmias immediately.
  • Avoid grapefruit and grapefruit juice, which may affect drug levels.

Special Considerations

Black Box Warnings:

  • None currently.

Genetic Factors: Genetic variations in CYP3A4 and UGT1A1 may affect drug metabolism.

Lab Test Interference: None significant.

Overdose Management

Signs/Symptoms: Unknown, but watch for signs of toxicity such as arrhythmias or liver dysfunction.

Treatment: Supportive care; no specific antidote. Contact poison control for guidance.

Storage and Handling

Storage: Store at 20°C to 25°C (68°F to 77°F), excursions permitted to 15°C to 30°C (59°F to 86°F).

Stability: Stable under proper storage conditions for the duration of the labeled expiry date.

🛡️ 5 Critical Medication Safety Tips for Nurses

1

Triple-Check High-Risk Medications

Always have another nurse verify insulin, heparin, warfarin, and chemotherapy drugs. These "high-alert" medications cause the most serious errors. Check concentration, dose calculation, and pump settings twice.

2

Know Look-Alike, Sound-Alike Drugs

Common mix-ups: hydromorphone/morphine, Celebrex/Celexa, Zyprexa/Zyrtec. Always use BOTH generic and brand names, read labels twice, and use barcode scanning when available. One wrong letter can be fatal.

3

Assess Before AND After Giving Meds

Check vitals before cardiac meds, pain levels before analgesics, and blood glucose before insulin. Always reassess within 30 minutes to evaluate effectiveness and watch for adverse reactions.

4

Watch for Drug Interactions

Common dangerous combinations: warfarin + aspirin (bleeding), ACE inhibitors + potassium (hyperkalemia), digoxin + diuretics (toxicity). Always check drug interactions before administering new medications.

5

Educate Your Patients

Teach patients medication names, purposes, major side effects, and what to report. Informed patients catch errors and improve compliance. Always encourage questions - an educated patient is a safer patient.

⚡ Remember: When in doubt, don't give it out! It's always safer to double-check than regret later.

⚠️ Medical Disclaimer

This drug guide is for educational purposes only and is NOT intended for clinical use. Always consult current prescribing information, healthcare providers, and institutional protocols before administering any medication. Do not use this information for patient care decisions.