Gefitinib: Difference between revisions

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<applet  load="" size="480" color="" frame="true"  spin="on" Scene ="Gefitinib/Gefitinib/1" align="right" caption="Gefitinib, also known as Iressa"/>
<StructureSection load='' size='450' side='right' scene='Gefitinib/Gefitinib/1' caption='Gefitinib, also known as Iressa'>
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===Better Known as: Iressa===
===Better Known as: Iressa===
* Marketed By: AstraZeneca & Teva
* Marketed By: AstraZeneca & Teva
* Major Indication: Pancreatic & Small Cel Lung [[Cancer]]
* Major Indication: Pancreatic & Small Cell Lung [[Cancer]]
* Drug Class: [[EGFR]] Inhibitor
* Drug Class: [[EGFR]] Inhibitor
* Date of FDA Approval (Expiration): 2003 (2013)
* Date of FDA Approval (Expiration): 2003 (2013)
* 2009 Sales: $268 Million
* 2009 Sales: $268 Million
* Importance: It is the first selective inhibitor of Epidermal Growth Factor Receptors approved by the FDA
* Importance: It is the first selective inhibitor of Epidermal Growth Factor Receptors approved by the FDA
* The following is a list of Pharmacokinetic Parameters. See: [[Pharmaceutical Drugs]] for more information
* See [[Pharmaceutical Drugs]] for more information about other drugs and disorders
===Pharmacokinetics===


{| class="wikitable" border="1" width="40%" style="text-align:center"
===Mechanism of Action===
|-
[[EGFR|Epidermal Growth Factor Receptors]] are overexpressed in many types of human [[Cancer|carcinomas]] including lung, pancreatic, and breast cancer. This overexpression leads to excessive activation of the anti-apoptotic [[Ras]] signalling cascade, resulting in uncontrolled [[DNA_Replication|DNA synthesis]] and cell proliferation. Studies have revealed that the <scene name='Gefitinib/Kinase/1'>EGFR tyrosine kinase domain</scene> is responsible for activating this Ras signaling cascade. Upon binding ligands like Epidermal Growth Factor, EGFR dimerizes and autophosphorylates several tyrosine residues at its C-terminal domain. It is these phosphorylated tyrosine residues which elicit downstream activation of other signaling proteins and subsequent signaling cascades.<ref>PMID:6090945</ref><ref>PMID:16729045</ref> Gefitinib inhibits the EGFR tyrosine kinase by <scene name='Gefitinib/Bound/1'>binding to the ATP-binding site</scene> located within the kinase domain. Residues Lys 745, Leu 788, Ala 743, Thr 790, Gln 791, Met 193, Pro 794, Gly 796, Asp 800, Ser 719, Glu 762, & Met 766 tightly bind the inhibitor. Unable to bind ATP, EGFR is incapable of autophosphorylating its C-terminal tyrosines, and the uncontrolled cell-proliferation signal is terminated.<ref>PMID:15284455</ref>
!  colspan="4" align="center"| EGFR Inhibitor [[Pharmaceutical_Drugs#Pharmacokinetics_Translated|Pharmacokinetics]] Comparison at Equivalent Dosages <ref>PMID:16609030</ref><ref>PMID:17482782</ref><ref>D. Smith et al. Br J Clin Pharmacol. 2009 April; 67(4): 421–426.</ref>
|-
! Parameter
! [[Erlotinib]] (Tarceva)
! [[Gefitinib]] (Iressa)
! Lapatinib (Tykerb)
|-
! [[Pharmaceutical_Drugs#Tmax|T<sub>max</sub>]] (hr)
! 2.0
! 5.4
! 8.3
|-
! [[Pharmaceutical_Drugs#Cmax|C<sub>max</sub>]] (ng/ml)
! 69.6
! 130
 
|-
! [[Pharmaceutical_Drugs#Bioavailability_.28F.29|Bioavailability]] (%)
! 99
! 59
! 29-49
|-
! [[Pharmaceutical_Drugs#Protein_Binding|Protein Binding]] (%)
! 93
! 90
! 99
|-
! [[Pharmaceutical_Drugs#Half_Life_.28T1.2F2.29|T<sub>1/2</sub>]] (hr)
! 9.4
! 26.9
! 29
|-
! [[Pharmaceutical_Drugs#Area_Under_the_Curve_.28AUC.29|AUC]] (ng/ml/hr)
! 20577
! 3850
! 11040
|-
! [[Pharmaceutical_Drugs#Inhibitory_Concentration_.28IC50.29|IC<sub>50</sub>]] (nM)
! 2
! 23
! 12
|-
! Typical Dosage (mg)
! 150
! 250
! 50
|-
! Metabolism
! Hepatic - (CYP3A4, CYP3A5, CYP2D6, CYP1A1)
! Hepatic - (CYP3A4, CYP3A5, CYP2D6, CYP1A1, CYP1A2)
! Hepatic (CYP3A4)
|}


===Pharmacokinetics===
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{{:Tyrosine Kinase Inhibitor Pharmacokinetics}}
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</table>
</StructureSection>
===References===
===References===
<references/>
<references/>
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Proteopedia Page Contributors and Editors (what is this?)Proteopedia Page Contributors and Editors (what is this?)

David Canner, Michal Harel, Joel L. Sussman