Drug interactions between Iressa and Tykerb
| Results for the following 2 drugs: |
|---|
| Iressa (gefitinib) |
| Tykerb (lapatinib) |
Interactions between your selected drugs
gefitinib ↔ lapatinib
Applies to:Iressa (gefitinib) and Tykerb (lapatinib)
MONITOR: Coadministration with inhibitors of CYP450 3A4 may increase the plasma concentrations of gefitinib, which is primarily metabolized by the isoenzyme. According to the product labeling, administration of gefitinib (250 mg single dose) with the potent inhibitor itraconazole (200 mg once a day for 12 days) increased the mean gefitinib systemic exposure (AUC) by 88% in healthy male volunteers. This increase may be clinically significant, as adverse events of gefitinib are related to dose and exposure.
MANAGEMENT: Caution is advised if gefitinib is administered with CYP450 3A4 inhibitors, particularly potent ones like itraconazole, ketoconazole, nefazodone, delavirdine, ketolide and certain macrolide antibiotics, and most protease inhibitors. Pharmacologic response to gefitinib should be monitored more closely whenever a CYP450 3A4 inhibitor is added to or withdrawn from therapy, and the dosage adjusted as necessary. Patients should be advised to contact their doctor if they experience possible symptoms of gefitinib toxicity such as severe diarrhea, nausea, dyspnea, cough, and fever.
See also...
Drug Interaction Classification
The classifications below are a guideline only. The relevance of a particular drug interaction to a specific patient is difficult to determine using this tool alone given the large number of variables that may apply.
| Major | Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit. |
| Moderate | Moderately clinically significant. Usually avoid combinations; use it only under special circumstances. |
| Minor | Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan. |
Do not stop taking any medications without consulting your healthcare provider.
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