Gefitinib Application Scope

It is indicated for the first-line treatment of adult patients with metastatic non-small cell lung cancer (NSCLC) whose tumors have epidermal growth factor receptor (EGFR) exon 19 deletions or exon 21 (L858R) substitution mutations as detected by an FDA-approved test.

Gefitinib Characteristics

Ingredients: Gefitinib 250 mg per tablet
Properties: Selective EGFR tyrosine kinase inhibitor
Packaging Specification: 250 mg × 30 tablets per bottle
Storage: Store at controlled room temperature 20–25°C (68–77°F)
Expiry Date: 24 months from the date of manufacture
Executive Standard: In line with Chinese Pharmacopoeia standards
Approval Number: National Drug Approval No. H20030001 (China)
Date of Revision: July 2025
Manufacturer: AstraZeneca Pharmaceuticals LP, USA

Guidelines for the Use of Iressa

Dosage and Administration:
- Recommended Dose: 250 mg once daily
- Administration: Take with or without food
- Missed Dose: Take as soon as remembered; skip if near next dose, do not double
Adverse Reactions:
- Common Adverse Reactions:
  - Rash
  - diarrhea
  - nausea
- Serious Adverse Reactions:
  - Interstitial lung disease
  - hepatotoxicity
  - gastrointestinal perforation
Contraindications: Hypersensitivity to it or excipients
Precautions: Use with caution in patients with liver dysfunction

Gefitinib Interactions

CYP3A4 Inhibitors:
- Drugs that are strong inhibitors of CYP3A4 (e.g., ketoconazole and itraconazole) decrease it metabolism and increase gefitinib plasma concentrations. Monitor adverse reactions when administering strong CYP3A4 inhibitors with Iressa.
CYP3A4 Inducers:
- Drugs that are strong inducers of CYP3A4 (e.g., rifampicin, phenytoin) increase the metabolism of it and decrease gefitinib plasma concentrations. Increase Iressa to 500 mg daily in patients receiving a strong CYP3A4 inducer and resume Iressa at 250 mg 7 days after discontinuation of the strong inducer.
Drugs Affecting Gastric pH:
- Drugs that elevate gastric pH (e.g., proton pump inhibitors, histamine H2-receptor antagonists, and antacids) may reduce plasma concentrations of gefitinib. Avoid concurrent use of Iressa with proton pump inhibitors, if possible. If treatment with a proton-pump inhibitor is required, take Iressa 12 hours after the last dose or 12 hours before the next dose of the proton-pump inhibitor. Take Iressa 6 hours after or 6 hours before an H2-receptor antagonist or an antaci.

Note:

If there is a new packaging for the drug, the new packaging shall prevail. The above information is sourced from DengYue Medicine.
This content is for reference only. Prescription drugs must be used under a doctor’s guidance and purchased from authorized sources.