The contraindicated population for Gefitinib includes individuals with a specific history of allergies, severe liver dysfunction, and pregnant women. The main contraindicated food is grapefruit, and the restrictions involve drug interactions and management of specific physiological states. Below are specific explanations of three types of taboos and restrictions.

1. Taboo population

(1) Allergic constitution: Those with a history of hypersensitivity reactions to gefitinib or lactose and other excipients in the preparation are absolutely prohibited.

(2) Liver dysfunction: It is contraindicated for patients with Child Pugh C grade severe liver injury, and close monitoring is required for mild to moderate damage.

(3) Pregnancy period: Animal studies have shown embryotoxicity, and pregnant women should avoid using it. Women of childbearing age need to confirm their pregnancy status before taking medication.

2. Forbidden foods

(1) Grapefruit/grapefruit juice: Contains strong CYP3A4 inhibitors, which may increase blood drug concentration and increase the risk of toxicity.

(2) High fat diet: may delay drug absorption, it is recommended to take on an empty stomach or 2 hours after meals to ensure bioavailability.

3. Restrictive conditions

(1) Drug interaction limitations

CYP3A4 inducers, such as phenytoin sodium and rifampicin, can reduce efficacy and should be avoided in combination or adjusted in dosage.

Acid suppressants: Proton pump inhibitors can reduce blood drug concentrations by 50% and should be taken at intervals of at least 6 hours.

(2) Special state restrictions

Breastfeeding period: It is unclear whether the medication has been administered to the breast. Breastfeeding should be suspended during the treatment period until 2 weeks after discontinuing the medication.

Elderly patients: Although there is no need to adjust the dosage, it is necessary to strengthen liver and kidney function and pulmonary toxicity monitoring due to comorbidities.

(3) Disease status restrictions

History of interstitial lung disease: Patients with previous ILD should be carefully evaluated for risk, and medication should be stopped immediately if new respiratory symptoms occur during use.

Corneal diseases: Patients with active keratitis or severe dry eye syndrome need to weigh the benefit risk ratio.