OBJECTIVE To analyze the potential adverse drug interactions based on pharmacokinetics （PK-pADIs） of gefitinib， and establish its corresponding prescription review rules. METHODS Outpatient prescriptions of gefitinib combination therapy in our hospital from January 1， 2022 to November 30， 2024 were collected through rational drug software system. PK- pADIs present in the prescriptions were identified based on the Drugs.com® drug interactions database. The specific combination drugs and cases of PK-pADIs were statistically analyzed， and prescription review rules were established according to the severity classification of PK-pADIs. RESULTS & CONCLUSIONS A total of 217 prescriptions of gefitinib combination therapy were enrolled. Among them， 28 prescriptions （12.90%）， involving a total of 28 patients， had 29 cases of PK-pADIs， with respiratory medicine prescriptions （22 prescriptions） being the main type. The combination drugs included proton pump inhibitors （13 cases）， strong cytochrome P450 3A4 （CYP3A4） inhibitors （7 cases）， H2 receptor antagonists （4 cases）， CYP3A4 inducers （3 cases）， and CYP2D6 substrates （2 cases）. The severity classifications for these interactions were severe， moderate， severe， moderate and moderate， respectively. Based on the above severity classification of PK-pADIs， four prescription review rules had been established as follows： when gefitinib was combined with acid-suppressing drugs， it should be subject to “manual review”； when gefitinib was combined with dexamethasone， metoprolol， or strong CYP3A4 inhibitors， an “alert” should be triggered， and the physician should be informed via an alert box to strengthen the monitoring of relevant indicators. Clinical pharmacists need to conduct in-depth training on knowledge related to gefitinib drug interactions in key clinical departments such as respiratory medicine. They should strengthen the monitoring and guidance of rational drug use for patients who are on long-term gefitinib therapy， and promptly identify and intervene in PK-pADIs， thereby enhancing the rationality， safety， and effectiveness of clinical drug use.