This guide provides a detailed overview of tucatinib's administration methods, recommended dosage, and adjustment principles in different populations. It offers scientific guidance for clinical practice, and patients are advised to consult their doctor before starting this medication.
Used Dosage for Adult Breast Cancer:
Oral administration of 300 mg twice daily, in combination with trastuzumab and capecitabine, until disease progression or unacceptable toxicity.
Used Dosage for Adult Colorectal Cancer:
Oral administration of 300 mg twice daily, in combination with trastuzumab, until disease progression or unacceptable toxicity.
Dose Adjustment in Cases of Renal Impairment:
Mild to moderate renal impairment (creatinine clearance 30-89 mL/min): Dose adjustment is not recommended.
Severe renal impairment (creatinine clearance less than 30 mL/min): Concomitant use of this drug with capecitabine and trastuzumab is not recommended.
Dosage Adjustment for Hepatic Impairment
Mild (Child-Pugh A) or moderate (Child-Pugh B) hepatic impairment: Dosage adjustment is not recommended.
Severe (Child-Pugh C) hepatic impairment: Reduce the dose to 200 mg orally twice daily.
Dosage Adjustment Related Notes
For dosage adjustment information on trastuzumab and capecitabine, please refer to their complete prescribing information.
Recommended Dose Reduction Procedure for Adverse Reactions
First dose reduction: 250 mg orally twice daily;
Second dose reduction: 200 mg orally twice daily;
Third dose reduction: 150 mg orally twice daily;
For patients who cannot tolerate 150 mg orally twice daily, this drug should be permanently discontinued.
Dose Adjustment for Adverse Reactions
Diarrhea
Grade 3 (not receiving antidiarrheal treatment): Initiate or intensify drug therapy; suspend this drug until recovery to Grade 1 or below; restart the drug at the same dose level. Grade 3 (already receiving antidiarrheal treatment): Initiate or intensify medication; discontinue this medication until grade 1 or below is reached; restart medication at a lower dose level.
Grade 4: Permanently discontinue treatment.
Hepatotoxicity
Grade 2: Elevated bilirubin (1.5-3 times the upper limit of normal): Discontinue treatment until grade 1 or below is reached; restart medication at the same dose level.
Grade 3: Elevated alanine aminotransferase (ALT) or aspartate aminotransferase (AST) (5-20 times the upper limit of normal), or grade 3: Elevated bilirubin (3-10 times the upper limit of normal): Discontinue treatment until grade 1 or below is reached; restart medication at a lower dose level.
Grade 4: Elevated ALT or AST (20 times the upper limit of normal), or grade 4: Elevated bilirubin (10 times the upper limit of normal): Permanently discontinue treatment.
If ALT or AST exceeds 3 times the upper limit of normal, and bilirubin exceeds 2 times the upper limit of normal: Permanently discontinue treatment.
Other Adverse Reactions
Grade 3: Suspend treatment until it returns to Grade 1 or below; restart medication at a lower dose level.
Grade 4: Permanently discontinue treatment.
Dose Adjustment When Used in Concomitantly with a Strong CYP4502C8 Inhibitor
Avoid concomitant use of this drug with a strong CYP4502C8 inhibitor.
If concomitant use with a strong CYP4502C8 inhibitor cannot be avoided, the dose of this drug should be reduced to 100 mg orally twice daily.
Resume the dose of this drug before starting concomitant use three elimination half-lives after discontinuing the strong CYP4502C8 inhibitor.
