The medication duration of letermovir tablets is usually 100 days after transplantation, which is a moderate period of preventive medication. Whether long-term use is necessary depends on the individual patient's condition and the doctor's evaluation.

1. Standard medication cycle

(1) Basic treatment course: continuous use for 100 days after hematopoietic stem cell transplantation

(2) Starting time: Medication is usually administered before or on the day of transplantation

(3) Basis of treatment: Covering the high-risk period of CMV infection after transplantation

2. Extended medication use

(1) Continued immune suppression: If the patient still requires potent immune suppression therapy

(2) CMV infection risk: adjusted based on virus load monitoring results

(3) Doctor evaluation: Regular clinical and laboratory evaluations are required

3 Adjustments for Special Groups

(1) Liver dysfunction: Children Pugh B patients do not need to adjust their time, but adverse reactions need to be monitored. It is recommended to take medication during the day for easy observation.

(2) Elderly people: For those with cognitive decline, it is recommended to have caregivers supervise medication and preferably administer it in the morning to reduce the risk of falls at night.

4 Dosage adjustment requirements

(1) Adverse reactions: When there is ≥ grade 3 bleeding, infection, or sustained grade 3 neutropenia, medication should be suspended and reduced or permanently discontinued after recovery.

(2) Combination therapy: When used in combination with strong CYP3A inhibitors, the dosage should be reduced to 100mgqd, and when used in combination with inducers, the dosage may need to be increased.

5 Medication precautions

(1) Non lifelong medication: not a medication that requires indefinite use

(2) Individualized plan: The specific treatment course needs to be combined with the type of transplant and complications

(3) Regular monitoring: CMV viral load and liver and kidney function should be monitored during medication

6 Precautions for Combination Medication

(1) Cyclosporine combination therapy: The dosage needs to be adjusted to 80mg once daily, and it is recommended to stagger the medication time for at least 2 hours.

(2) Antacid use: Antacids containing aluminum/magnesium should be taken every 2 hours to avoid affecting the absorption of letamivir.