Gefitinib is a tyrosine kinase inhibitor indicated for the first-line treatment of 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. Limitation of Use: Safety and efficacy of Gefitinib have not been established in patients whose tumors have EGFR mutations other than exon 19 deletions or exon 21 (L858R) substitution mutations.
Gefitinib inhibits the epidermal growth factor receptor (EGFR) tyrosine kinase by binding to the adenosine triphosphate (ATP)-binding site of the enzyme. Thus the function of the EGFR tyrosine kinase in activating the Ras signal transduction cascade is inhibited; and malignant cells are inhibited. Gefitinib is the first selective inhibitor of the EGFR tyrosine kinase which is also referred to as Her1 or ErbB-1. EGFR is overexpressed in the cells of certain types of human carcinomas - for example in lung and breast cancers. Overexpression leads to inappropriate activation of the apoptotic Ras signal transduction cascade, eventually leading to uncontrolled cell proliferation.
The recommended dose of Gefitinib is 250 mg orally once daily with or without food until disease progression or unacceptable toxicity. Do not take a missed dose within 12 hours of the next dose.
Concomitant use with CYP3A4 inducers (e.g. rifampicin, phenytoin, carbamazepine, barbiturates) may reduce serum Genib levels. Plasma concentrations may be increased with potent CYP3A4 inhibitors (e.g. itraconazole, ketoconazole). Increased INR or bleeding events with warfarin. May increase plasma levels of metoprolol. May exacerbate vinorelbine-induced neutropenia. Decreased plasma levels and potential reduction in efficacy with drugs that affect gastric pH (e.g. PPIs, H2-receptor antagonists).
Hypersensitivity. Lactation.
Common side effects are pruritus, rash, angioedema, urticaria, epistaxis, haematuria, alopecia, dry mouth and skin, nausea, vomiting, anorexia, stomatitis, diarrhoea, nail disorders, asthenia, pyrexia, proteinuria, eye pain, corneal erosion or ulcer, aberrant eyelash growth and elevations in blood creatinine. Rarely, pancreatitis, erythema multiforme, toxic epidermal necrolysis, corneal membrane sloughing, ocular ischemia, or ocular haemorrhage.
Pregnancy category D. There is positive evidence of human foetal risk, but the benefits from use in pregnant women may be acceptable despite the risk (e.g., if the drug is needed in a life-threatening situation or for a serious disease for which safer drugs cannot be used or are ineffective).
Overdose may include: diarrhea that is severe or doesn't stop, severe skin rash.
Each film-coated tablet contains; 250 mg of gefitinib
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