Letimovir is a cell proliferation virus terminal transferase inhibitor that inhibits the activity of CMV DNA terminal enzyme complexes (including pUL51, pUL56, and pUL89), blocking CMV DNA replication and suppressing virus proliferation.

1、 Drug name

1. Common name: Letimovir

2. English name: Letermovir

3. Product Name: PREVYMIS ®

2、 Indications

1. Used to prevent CMV infection and disease in recipients of Cytomegalovirus (CMV) seropositive (R+) allogeneic hematopoietic stem cell transplantation (HSCT) who are 6 months or older and weigh at least 6kg.

2. Used to prevent CMV disease in high-risk (donor CMV positive/recipient CMV negative, D+/R -) kidney transplant recipients aged 12 years and above, weighing at least 40kg.

3、 Specifications and characteristics

Tablets: 240mg

4、 Main components

1. Active ingredient: Letermovir

2. Accessories include colloidal silica, cross-linked carboxymethyl cellulose sodium, magnesium stearate, microcrystalline cellulose, polyvinylpyrrolidone, etc. The injection also contains hydroxypropyl betacyclodextrin.

5、 Usage and dosage

1. Adults and patients aged 12 and above with a weight of ≥ 30kg (HSCT) or ≥ 40kg (kidney transplant): The recommended dose is 480mg, administered orally or intravenously once daily (infusion time of 1 hour).

2. HSCT patients aged 6 months to 12 years or under, or weighing less than 30kg: adjust dosage according to weight.

3. Treatment cycle: HSCT recipients usually receive it up to 100 days after transplantation, and high-risk patients can extend it up to 200 days; Kidney transplant recipients up to 200 days after transplantation.

4. Oral tablets can be taken with food or alone, and should be swallowed whole

6、 Dose adjustment

1. When used in combination with cyclosporine, the dose of ritomo should be reduced to 240mg once daily in patients aged 12 and above; Children under 12 years old need to adjust their dosage according to their weight.

2. Patients with moderate to severe liver injury (Child Pugh B or C) should use it with caution, and severe liver injury (Child Pugh C) is not recommended for use.

3. Patients with renal insufficiency generally do not need to adjust the dosage, but serum creatinine should be monitored when using injections (as hydroxypropyl betacyclodextrin may accumulate).

7、 Medication precautions

1. It can be taken before and after meals.

2. If missed, it should be replenished as soon as possible; If it is close to the next medication time, skip the missed dose and do not double the dosage.

3. If vomiting occurs after taking the medication, it is not recommended to take it again. The next dose should be taken according to the original plan.

4. Injections should only be used for patients who cannot take them orally and should be converted to oral preparations as soon as possible.

5. Injections require the use of infusion bags and devices that do not contain diethylhexyl phthalate (DEHP).

8、 Medication for special populations

1. Pregnant women: Without sufficient human data, it is necessary to weigh the pros and cons.

2. Breastfeeding period: Unknown if it has entered breast milk, use with caution.

3. Children: HSCT recipients over 6 months old and kidney transplant recipients over 12 years old can use it, but safety has not been established for younger or lower weight recipients.

4. Elderly: No need to adjust dosage.

9、 Adverse reactions

1. HSCT recipients commonly experience nausea, diarrhea, vomiting, peripheral edema, cough, headache, fatigue, and abdominal pain.

2. Common occurrence in kidney transplant recipients: diarrhea.

3. Adverse reactions in children are similar to those in adults.

4. Injections may cause nephrotoxicity or ototoxicity due to accumulation of hydroxypropyl betaine paste (based on animal data).

10、 Contraindications

1. It is prohibited to use it in combination with pimozide and ergot alkaloids.

2. When used in combination with cyclosporine, it is prohibited to use pitavastatin or simvastatin.

11、 Drug interactions

1. Letimovir is a CYP3A and moderate inhibitor combined with OATP1B1/3 inhibitor, which may increase the concentration of drugs metabolized through these pathways when used in combination.

2. The combination with cyclosporine will significantly increase the concentration of letamivir, and the dosage needs to be adjusted.

3. It should be avoided to use strong inducers such as rifampicin, carbamazepine, and St. John's wort in combination, as it may lead to the failure of Remdesivir.

12、 Storage method

1. Tablets: Store in original packaging, moisture-proof, 20 ° C-25 ° C (15 ° C-30 ° C allowed).

2. All dosage forms should be kept out of reach of children.

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