Gefitinib Pharmacology


About Gefitinib
Antineoplastic Agents,Protein Kinase Inhibitors
Mechanism of Action of Gefitinib
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.
Pharmacokinets of Gefitinib
Absorption:Absorbed slowly after oral administration with mean bioavailability of 60%.
Distribution: Protein binding 90% primarily to serum albumin and alpha 1-acid glycoproteins.
Metabolism: Metabolism Primarily hepatic via CYP3A4.
Elimination:Primarily via feces,less than 4% via renal.
Onset of Action for Gefitinib
Duration of Action for Gefitinib
Half Life of Gefitinib
Side Effects of Gefitinib
8.Skin reactions
10.Asymptomatic elevations of liver enzymes
Contra-indications of Gefitinib
Special Precautions while taking Gefitinib
1.Severe renal or hepatic impairment
2.Idiopathic pulmonary fibrosis
3.Acute onset or worsening of pulmonary or eye symptoms
4.Monitor hepatic function periodically
5.Monitor regularly for changes in prothrombin time or International Normalized Ratio in patients on warfarin treatment
Pregnancy Related Information
Old Age Related Information
Use with caution
Breast Feeding Related Information
Children Related Information
Not recommended
Indications for Gefitinib
For the continued treatment of patients with locally advanced or metastatic non-small cell lung cancer after failure of either platinum-based or docetaxel chemotherapies.

Interactions for Gefitinib
1.Gefitinib may increase the blood-thinning effects of warfarin andd increase the risk of bleeding.
2.Patients who receive drugs that increase an enzyme in the liver called CYP 3A4 that destroys gefitinib (e.g., rifampin or phenytoin ) may need a higher dose of gefitinib to maintain the effectiveness of gefitinib.
3.Patients who receive drugs that reduce CYP 3A4, e.g., ketoconazole, itraconazole , fluconazole , erythromycin, clarithromycin, ritonavir, nelfinavir , indinavir , nefazodone, as well as grapefruit juice, may need a lower dose of gefitinib to prevent side effects from increased levels of gefitinib.
Typical Dosage for Gefitinib
Gefitinib is taken by mouth. The dose is 250 mg once daily. The dose is the same for men or women of any age or weight, and gefitinib can be taken with or without food.

Schedule of Gefitinib
Storage Requirements for Gefitinib
Store at room temperature between 68 and 77 degrees F (20-25 degrees C) away from light and moisture.
Effects of Missed Dosage of Gefitinib
If you miss a dose, use it as soon as you remember. If it is less than 12 hours before the next dose, skip the missed dose and resume your usual dosing schedule. Do not double the dose to catch up.
Effects of Overdose of Gefitinib
There is no specific treatment for an overdose and possible symptoms of overdose are not established. However, in Phase 1 clinical trials, a limited number of patients were treated with daily doses of up to 1000 mg. An increase in frequency and severity of some adverse reactions was observed, mainly diarrhea and skin rash. Adverse reactions associated with overdose should be treated symptomatically; in particular, severe diarrhea should be managed appropriately.

Home Delivery for Gefitinib in Your City

Medicine India is just a publishing medium for medicine related information and does not provide services or sales of medicines including gefitinib.

However, we do publish a comprehensive directory of Pharmacies, Chemists and Druggists in cities all over India. You can use this directory to find the medicine stores in your city (or area) that provide home delivery services for gefitinib and other medicines and health products. Home delivery services for gefitinib may be free or they may cost you depending on the pharmacy and the minimum order requirements. It would be best to get this clarified while placing the order.

Please be aware that you should take gefitinib only if a doctor has recommended or prescribed it. Some or all pharmacies who provide a home delivery service for medicines might insist on a prescription for gefitinib before they complete the sale. You can get this information while placing the order for gefitinib with the pharmacy.

Gefitinib is a generic medicine name and there are several brands available for it. Some of the brands for gefitinib might be better known than gefitinib itself. If the pharmacy that's willing to deliver medicines to your home doesn't have gefitinib in stock, you can ask for one of the branded alternatives for gefitinib.