Letermovir tablets are an antiviral drug mainly used to prevent cytomegalovirus (CMV) infection, particularly suitable for high-risk patients after hematopoietic stem cell transplantation (HSCT). This drug works by inhibiting the CMV virus terminating enzyme complex and has the characteristics of high efficiency and low toxicity. The duration of use of letermovir tablets usually depends on the need to prevent cytomegalovirus (CMV) infection, and is generally used for CMV prevention in high-risk patients after hematopoietic stem cell transplantation (HSCT). The standard course of treatment is 100 days after transplantation, but may be extended depending on the patient's immune recovery.

1. Basic information of the drug

(1) Common name: Letermovir

(2) Mechanism of action: Selective inhibition of CMV virus DNA terminating enzyme complex

(3) Administration route: Oral tablets or intravenous injection

2 main indications

(1) Preventing CMV infection: for adult patients with CMV serological positivity after HSCT

(2) High risk population: suitable for patients undergoing allogeneic hematopoietic stem cell transplantation

3 characteristics of medication

(1) Preventive medication: usually started before or on the day of transplantation

(2) Duration of treatment: The standard treatment period is 100 days after transplantation, which can be extended according to the situation

(3) Advantage features: Compared with traditional anti CMV drugs, the risk of bone marrow suppression is lower

4 standard medication cycles

(1) Basic treatment course: It is recommended to start administering medication before or on the day of transplantation and continue until 100 days after transplantation.

(2) Extended medication: For patients with sustained immune suppression or CMV serological positivity, it may be necessary to extend the medication until 200 days after transplantation.

5 Special Adjustment Situations

(1) Delayed immune recovery: If CD4+T cell count does not meet the standard, medication should be extended until immune function is restored.

(2) Secondary transplantation: Patients who receive a secondary transplantation need to recalculate their treatment course for 100 days.

6 Evaluation indicators for drug discontinuation

(1) Immune reconstitution: CD4+T cells>50/μ L and discontinuation of immunosuppressants may be considered for drug discontinuation.

(2) Virus monitoring: Two consecutive CMV-DNA tests were negative and there were no clinical symptoms of infection.