Selumetinib should be strictly screened for contraindications before use, and the following three types of patients should be particularly vigilant to avoid serious adverse events.

1、 Patients with decreased left ventricular ejection fraction

1. Baseline assessment

Left ventricular ejection fraction (LVEF) must be measured by echocardiography or MUGA scan before treatment.

If the baseline LVEF is below the lower limit of normal or below 50%, treatment should generally not be initiated.

2. Monitoring during treatment

During medication, LVEF should be regularly reviewed (e.g. every 3 months).

If LVEF decreases by more than 10 percentage points and the absolute value is less than 50%, medication should be suspended and evaluated for restart after recovery.

3. Be alert to symptoms of heart failure

When experiencing shortness of breath, lower limb edema, inability to lie flat at night, or decreased activity endurance, seek medical attention immediately to assess cardiac function.

2、 Severe liver injury patients

1. Baseline liver function testing

ALT, AST, and total bilirubin should be tested before treatment.

Patients with severe liver injury (such as Child Pugh C grade or bilirubin>3 times the upper limit of normal) should not use it.

2. Monitoring during medication use

Recheck liver function every 2 weeks for the first 3 months, and then every month thereafter.

If the transaminase level rises more than three times the normal upper limit and is accompanied by an increase in bilirubin, the medication should be stopped immediately.

3. Identification of liver toxicity symptoms

Notify the doctor promptly when experiencing fatigue, nausea, upper right abdominal pain, jaundice, or dark urine.

3、 Pregnant women and women preparing for pregnancy

1. Pregnancy testing

Women with fertility need to complete a serum pregnancy test 7 days before initiating treatment to confirm a negative result.

2. Effective contraception

During the treatment period and at least one month after discontinuation, two highly effective contraceptive measures (such as oral contraceptives and barrier method) must be used.

3. Fetal risk notification

Use during pregnancy may cause harm to the fetus. If pregnancy occurs during treatment, immediately inform the doctor and terminate the medication.