The contraindications for Tucatinib include patients with severe liver injury and QT interval prolongation, and strict adherence to medication contraindications is necessary to avoid serious adverse reactions. Patients with severe liver injury need to adjust the dosage or discontinue use. Prolonged QT interval may cause fatal arrhythmias and require close monitoring of the electrocardiogram.

1. Severe liver injury patient

(1) The standard dose is contraindicated for patients with Child Pugh C-grade liver dysfunction, and the recommended dose adjustment is 200mg twice a day.

(2) During the treatment period, if bilirubin>3-10 × ULN or ALT/AST>5-20 × ULN occurs, medication should be suspended and the dose should be reduced after recovery; Patients with liver failure need to permanently discontinue medication.

(3) Monitor liver function (ALT/AST/bilirubin) before medication and every 3 weeks. If symptoms such as jaundice and ascites occur, seek medical attention immediately.

Patients with prolonged 2-QT interval

(1) Patients with a baseline QTc interval>500 milliseconds or a history of arrhythmia are contraindicated, as it may increase the risk of apical torsion to ventricular tachycardia.

(2) During the treatment period, if symptoms such as palpitations and fainting occur, an electrocardiogram should be performed immediately. If QTc>500 milliseconds, medication should be discontinued.

(3) Caution should be exercised when using other QT prolonging drugs in combination, and if necessary, adjust the dosage or switch to alternative therapies.

3 Other taboo groups

(1) Prohibited during pregnancy: Animal experiments have shown embryotoxicity, and women of childbearing age should strictly use contraception during the medication period and within one week of discontinuation.

(2) Prohibition during lactation: The medication may be secreted through breast milk and should be stopped for 7 days before resuming breastfeeding.

(3) It is contraindicated for individuals allergic to the ingredients of Tukatinib, as severe hypersensitivity reactions may occur.