From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Elevated AST levels alone typically do not require cisplatin dose reduction when used with trastuzumab. Cisplatin is primarily eliminated through renal excretion, not hepatic metabolism, so liver enzyme elevations have less impact on its clearance 1. However, you should evaluate the degree of AST elevation and look for other signs of liver dysfunction. If the patient has severe hepatic impairment (indicated by multiple abnormal liver function tests, elevated bilirubin, or clinical signs of liver disease), then dose modification may be warranted.
Some key points to consider:
- Renal function is more critical for cisplatin dosing, so ensure the patient's creatinine clearance is adequate (typically >60 mL/min for full dosing) 1.
- Monitor the patient closely for cisplatin toxicity, including nausea, vomiting, nephrotoxicity, and neurotoxicity.
- If the AST elevation is due to the cancer itself, treating with appropriate chemotherapy may actually improve liver function.
- Consult with a clinical pharmacist or oncology specialist if you're uncertain, as individual patient factors may influence this decision.
It's also worth noting that trastuzumab has been associated with hepatotoxicity in some cases, as reported in a study from 2008 2. However, this is not directly relevant to the decision of whether to reduce the dose of cisplatin. The most recent and highest quality study on the topic of cisplatin hepatotoxicity and exercise suggests that high-intensity interval training may alleviate liver inflammation and promote hepatoprotective effects 1.