Erlotinib (Mechanism of Action)

In this article, we will discuss Erlotinib (Mechanism of Action). So, let’s get started.

Erlotinib (TARCEVA®), a kinase inhibitor, is a quinazolinamine with the chemical name N-(3-cthynylphenyl)-6,7-bis(2-methoxyethoxy)-4-quinazolinamine.

Erlotinib hydrochloride has the molecular formula C22H23N3O4.HCl and a molecular weight of 429.90. The molecule has a pKa of 5.42 at 25°C. Erlotinib hydrochloride is very slightly soluble in water, slightly soluble in methanol and practically insoluble in acetonitrile, acetone, ethyl acetate and hexane.

Aqueous solubility of erlotinib hydrochloride is dependent on pH with increased solubility at a pH of less than 5 due to protonation of the secondary amine. Over the pH range of 1.4 to 9.6, maximal solubility of approximately 0.4 mg/mL occurs at a pH of approximately 2.

Erlotinib (TARCEVA®) tablets for oral administration are available in three dosage strengths containing erlotinib hydrochloride (27.3 mg. 109.3 mg
and 163.9 mg) equivalent to 25 mg, 100 mg and 150 mg erlotinib and the following inactive ingredients: lactose monohydrate, hypromellose, hydroxypropyl cellulose, magnesium stearate, microcrystalline cellulose, sodium starch glycolate, sodium lauryl sulfate and titanium dioxide.

Mechanism of Action

Epidermal growth factor receptor (EGFR) is expressed on the cell surface of both normal and cancer cells. In some tumor cells signaling through this receptor plays a role in tumor cell survival and proliferation irrespective of EGFR mutation status. Erlotinib reversibly inhibits the kinase activity of EGFR, preventing autophosphorylation of tyrosine residues associated with the receptor and thereby inhibiting further downstream signaling. Erlotinib binding affinity for EGFR exon 19 deletion or exon 21 (L858R) mutations is higher than its affinity for the wild type receptor. Erlotinib inhibition of other tyrosine kinase receptors has not been fully characterized.

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