During the use of rituximab, strict screening of concomitant medications is necessary to avoid co administration with pimozide and ergotamine; Monitor liver function monthly and discontinue medication promptly if significant elevation is detected; Transplant patients should closely monitor the concentration of immunosuppressive drugs and organ function to detect and treat signs of rejection early.

1、 Drug interactions

1.1 Medications that should be avoided in combination

Pimozide: Combination use can cause serious cardiac toxicity and is absolutely contraindicated.

Ergot alkaloids (such as dihydroergotamine): Combination use can cause peripheral ischemia, absolutely contraindicated.

Cyclosporine: When used in combination, the dose of letamivir should be halved to 240mg/day, and restored to 480mg/day after discontinuing cyclosporine.

1.2 Medications to be used in combination with caution

Tacrolimus and Sirolimus: Combination use may increase their blood drug concentration, and monitoring frequency needs to be increased.

Antifungal drugs (such as voriconazole): metabolized by CYP3A4, interactions should be monitored when used in combination.

1.3 Traditional Chinese Medicine and Health Products

Avoiding the use of St. John's wort can significantly reduce the efficacy of Remdesivir.

2、 Hepatotoxicity monitoring

2.1 Monitoring indicators and frequency

Perform monthly liver function tests (ALT, AST, total bilirubin, alkaline phosphatase) before and during treatment.

2.2 Exception Handling

Elevated transaminase levels above 5 × ULN or jaundice (total bilirubin>2 × ULN): Medication should be suspended and liver function should be rechecked weekly.

Combined symptoms of liver injury (such as fatigue, upper right abdominal pain, fever): Stop medication immediately and investigate other causes.

2.3 High risk population

Individuals with pre-existing liver dysfunction, viral hepatitis, or concomitant use of hepatotoxic drugs should increase their monitoring frequency (once every 2 weeks).

3、 Monitoring of transplant rejection reactions

3.1 Key points of clinical observation

Monitor indicators related to transplant function, such as changes in kidney function, blood routine, and bone marrow function.

Pay attention to newly developed or aggravated fever, rash, and organ dysfunction, which may indicate rejection reactions.

3.2 Monitoring of immunosuppressive drug concentration

If taking tacrolimus or cyclosporine at the same time, the dosage should be adjusted according to their blood drug concentration to avoid insufficient immune suppression caused by the interaction of letemovir.

When renal function fluctuates, the risk of rejection and the balance of anti infective treatment should be evaluated in a timely manner.