erlotinib or gefitinib (39dce2)

**Erlotinib or gefitinib** is a non-specific paired reference to either of two distinct first-generation, orally administered epidermal growth factor receptor tyrosine kinase inhibitors: erlotinib and gefitinib. It does not denote a single chemical entity, a fixed-dose product, or a combination regimen. Both agents reversibly compete with ATP at the intracellular kinase domain of epidermal growth factor receptor, suppressing EGFR autophosphorylation and downstream proliferative and survival signaling. They have been used for epidermal growth factor receptor mutation-positive advanced or metastatic non-small cell lung cancer, but their molecular structures, pharmacokinetics, developers, brands, and regulatory histories are distinct and should be annotated as separate drug records when a specific agent is intended.