| Item |
Information |
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Drug Groups
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approved; investigational |
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Description
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Gefitinib (originally coded ZD1839) is a drug used in the treatment of certain types of cancer. Acting in a similar manner to erlotinib (marketed as Tarceva), gefitinib selectively targets the mutant proteins in malignant cells. It is marketed by AstraZeneca under the trade name Iressa. [Wikipedia] |
| Indication |
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. |
| Pharmacology |
Gefitinib inhibits the intracellular phosphorylation of numerous tyrosine kinases associated with transmembrane cell surface receptors, including the tyrosine kinases associated with the epidermal growth factor receptor (EGFR-TK). EGFR is expressed on the cell surface of many normal cells and cancer cells. |
| Toxicity |
The acute toxicity of gefitinib up to 500 mg in clinical studies has been low. In non-clinical studies, a single dose of 12,000 mg/m2 (about 80 times the recommended clinical dose on a mg/m2 basis) was lethal to rats. Half this dose caused no mortality in mice. Symptoms of overdose include diarrhea and skin rash. |
| Affected Organisms |
| • |
Humans and other mammals |
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| Biotransformation |
Primarily hepatic via CYP3A4. Three sites of biotransformation have been identified: metabolism of the N-propoxymorpholino-group, demethylation of the methoxy-substituent on the quinazoline, and oxidative defluorination of the halogenated phenyl group. |
| Absorption |
Absorbed slowly after oral administration with mean bioavailability of 60%. |
| Half Life |
48 hours |
| Protein Binding |
90% primarily to serum albumin and alpha 1-acid glycoproteins. |
| Elimination |
Elimination is by metabolism (primarily CYP3A4) and excretion in feces. Excretion is predominantly via the feces (86%), with renal elimination of drug and metabolites accounting for less than 4% of the administered dose. |
| Distribution |
* 1400 L |
| Clearance |
* 595 mL/min |
| References |
| • |
Pao W, Miller V, Zakowski M, Doherty J, Politi K, Sarkaria I, Singh B, Heelan R, Rusch V, Fulton L, Mardis E, Kupfer D, Wilson R, Kris M, Varmus H: EGF receptor gene mutations are common in lung cancers from "never smokers" and are associated with sensitivity of tumors to gefitinib and erlotinib. Proc Natl Acad Sci U S A. 2004 Sep 7;101(36):13306-11. Epub 2004 Aug 25.
[Pubmed]
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| • |
Sordella R, Bell DW, Haber DA, Settleman J: Gefitinib-sensitizing EGFR mutations in lung cancer activate anti-apoptotic pathways. Science. 2004 Aug 20;305(5687):1163-7. Epub 2004 Jul 29.
[Pubmed]
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| External Links |
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