Note: before purchasing and taking medicines, a hospital genetic test report and a doctor's diagnosis report or certificate must be produced
The clinic is primarily designed for the treatment of locally advanced or metastatic non-small cell lung cancer previously treated with chemotherapy. Especially for lung adenocarcinoma, the efficacy is exact, for squamous cell carcinoma is lower than that for adenocarcinoma and alveolar carcinoma, but a large amount of clinical data show that: after the treatment with Iressa (gefitinib) is selected according to the actual situation of lung cancer patients, there are still some patients with lung squamous carcinoma and other non-small cell lung cancer, the effect is more obvious, and it is well tolerated.
The recommended dose of this article is 250 mg (1 tablet), once a day, taken orally, on an empty stomach, or taken with food.
Tablets may be dispersed in half a glass of drinking water (non carbonated drink) if there is dysphagia. No other liquids may be used. The tablets were lost into water without crushing, stirred until fully dispersed (taking about 10 min), and immediately drunk. Rinse the cup with half water and drink down. The drug may also be administered via a naso gastric tube.
There is no need to adjust the administered dose differently for: age, weight, gender, race, renal function, moderate to severe hepatic impairment due to liver metastases.
Dose adjustment: when patients develop intolerable diarrhea or cutaneous adverse effects, which resolve with short-term suspension of therapy followed by resumption of the 250 mg daily dose (see adverse effects).
Note: at present, there are no data about the safety and efficacy of this product in children or adolescents, so it is not recommended.
Severe allergic responders to the active substance or to either of the excipients of the product are known.
Common (occurring in > 20% of patients) adverse drug reactions are diarrhea, rash, pruritus, dry skin, and acne, generally seen within 1 month of taking the drug and usually reversible.
Drug drug interactions
In vitro assays performed on human liver microsomes confirmed that gefitinib is mainly metabolized by CYP3A4 via the hepatic cytochrome P-450 system. So gefitinib might interact with drugs that induce, inhibit, or metabolize for the same liver enzymes. Animal studies have shown little enzyme induction by gefitinib, and in vitro studies have shown limited CYP2D6 inhibition by gefitinib.
The following lists drugs or drug classes that interact with drugs that gefitinib produces or may produce clinically meaningful effects:
1) Drugs that affect gefitinib - with a proven interaction - drugs that inhibit CYP3A4, combining gefitinib with itraconazole (a CYP3A4 inhibitor) in healthy volunteers increased the mean AUC of gefitinib by 80%. Because adverse drug reactions are dose and exposure related, this elevation may be clinically significant. Although interactions with other CYP3A4 inhibitors were not investigated, it is equally likely that drugs in this class such as ketoconazole, clotrimazole, ritonovir inhibit the metabolism of gefitinib.
2) Agents that raise gastric pH - clinical studies in healthy volunteers have shown that coadministration with agents that significantly and consistently raise gastric pH to ≥ 5 lowers the mean AUC of gefitinib by 47%, which may reduce gefitinib efficacy.
3) Rifampicin - when gefitinib was administered concomitantly with rifampicin, a known strong CYP3A4 inducer, in healthy volunteers, the mean AUC of gefitinib was reduced by 83% compared with when it was administered alone.
4) There may in theory be interacting drugs - other CYP3A4 inducers, substances that induce CYP3A4 activity that increase gefitinib metabolism and decrease its plasma concentration. Therefore, coadministration with CYP3A4 inducers (e.g., phenytoin, carbamazepine, barbiturates, or St. John's wort) reduces efficacy.
5) The effect of gefitinib on other drugs - drugs that have been shown to interact - is mediated through CYP2D6 metabolism, and in one clinical trial, gefitinib co administered with metoprolol, a substrate of the CYP2D6 enzyme, increased metoprolol exposure by 35%, which was not considered clinically relevant. Gefitinib, administered concomitantly with other drugs metabolized by CYP2D6, may elevate the latter blood concentrations.
6) Theoretically there may be interacting drugs - warfarin: although formal drug interaction studies have not been performed to date, increased INR and / or bleeding events have been reported in some patients taking warfarin. Patients taking warfarin should be monitored periodically for alterations in their prothrombin time or INR.
7) Vinorelbine - in a phase II study, this product was administered concomitantly with vinorelbine, which was shown to potentially exacerbate vinorelbine induced neutropenia.