What foods or drugs should not be taken with targeted drugs during targeted therapy?
Foods and medications that affect CYP3A4 should not be taken
The cytochrome P450 3A4 enzyme, or “CYP3A4” for short, is an important enzyme in the body. Commonly targeted drugs, such as Gefitinib (trade name e.g., Erythroxel) for EGFR mutations and Crizotinib (trade name e.g., Securitas) for ALK mutations, are metabolized by CYP3A4.
Some foods or drugs can affect CYP3A4, and thus the metabolism of targeted drugs, and should be avoided during treatment.
1. Common foods that affect CYP3A4
Mainly grapefruit fruits, such as grapefruit and grapefruit. Studies have found that grapefruit juice is metabolized in the body, by CYP3A4, which simultaneously inhibits the activity of this enzyme. If grapefruit is often eaten while taking the drug, the metabolism of gefitinib and crizotinib is affected.
Therefore, doctors do not recommend eating grapefruit (including drinking grapefruit juice) while taking medications to avoid affecting drug metabolism, increasing drug accumulation in the body, and worsening adverse effects.
2. Common drugs that affect CYP3A4
- Non-sedating antihistamines, such as terfenadine;
- Calcium antagonists (a commonly used hypotensive drug): e.g. nifedipine, felodipine, verapamil;
- Gastrointestinal motility enhancers: e.g., cisapride;
- Statin (a commonly used lipid-lowering drug): e.g. atorvastatin, lovastatin;
- Benzodiazepine sedative-hypnotics: e.g., alprazolam, diazepam;
- Immunosuppressants (therapeutic agents to combat rejection after organ transplantation): e.g. cyclosporine.
In addition, because targeted drugs are metabolized primarily in the liver, it is also important to avoid other drugs that affect liver function. Therefore, you should fully communicate with your primary care physician prior to targeted therapy to inform him or her which medications you are using to avoid compromising efficacy or adverse reactions.
No need to take more “other drugs”
Many patients want to take more “other drugs” during targeted therapy, but this is not necessary. If the tumor is well controlled with targeted therapy, then taking targeted drugs every day is the easiest, most reasonable, and most economical way.
A special word of caution: many international clinical studies do not allow patients taking Chinese medicine to participate. Therefore, if you are thinking of enrolling in a clinical study, you should talk to your primary care physician in a timely manner to develop an individualized and optimal plan for you.
In general, diet does not require much modification during targeted therapy, but care should be taken to avoid the drugs and foods mentioned above that may interfere with the metabolism of targeted drugs.
Co-reviewed by Dr. Qing Zhou, Chief Physician, Guangdong Provincial People’s Hospital, Guangdong Lung Cancer Institute Dr. Xiaoyan Bai Yichen Zhang