Erlotinib review

Erlotinib is a cancer therapy drug used to treat non-small cell lung and pancreatic cancer. Prior to its name, it has been coded as OSI-774.

Erlotinib is analogous to gefitinib, which targets the EGFR tyrosine kinase (epidermal growth factor receptor). This kyrosine is known to be highly mutated in various forms of cancer. Its action is to bind in the ATP of the receptor. By inhibiting the ATP, it stops autophosphorylation of the cell and the signal stops.

Erlotinib is also known as Tarceva, and is used to treat patients with locally advanced or metastatic non-small lung, pancreatic and other forms of cancer when at least one round of chemotherapy has failed.

Erlotinib or Tarceva comes in tablet form for oral administration and is available in three dosage strengths. The following strengths are 27.3 mg, 109.3 mg and 163.9mg of erlotinib hydrochloride equivalent to 25mg, 100 mg and 150 mg tablets of erlotinib and its inactive ingredients of hypromellose, lactose monohydrate, magnesium stearate, hydroxypropyl cellulose, sodium starch glycolate, microcrystalline cellulose, titanium dioxide and sodium lauryl sulfate.

Most commonly reported side effects of erlotinib use include skin rashes, appetite loss, diarrhea, nausea and fatigue. Skin rashes appear like acne and may occur in the face and the neck. The more serious side effects such as lung failure and even death have been reported, although the occurrence is very low.

The occurrence of interstitial pneumonitis as a side effect of erlotinib use has also been reported. This is characterized by an increased dyspnea and cough, as well as difficulty in breathing. This is a severe side effect and must be treated with emergency medical attention. Erlotinib use has also been reported to cause hearing loss and partial hair loss.

Erlotinib is contraindicated in patients with hypersensitivity to the drug or its components. Patients concurrently taking drugs that inhibit the action of CYP3A4 enzyme is found to be contraindicated with erlotinib as it may cause patient toxicity in erlotinib. CYP3A4 is a liver enzyme that metabolizes erlotinib in the body. Such CYP3A4 inhibiting drugs include atazanavir, indinavir, ketoconazole, clarithromycin, and nefadozone among others. For patients receiving therapy on these drugs, a lower dose of erlotinib may be administered to prevent toxicity.

Drugs that increase CYP3A4 activity, in turn, reduces the levels of erlotinib in the body. Such drugs include rifabutin, rifampicin, phenytoin, Phenobarbital, and carbamazepine among others. Such drugs must be avoided when taking erlotinib. However, in cases where these drugs may not be avoided, a higher dose of erlotinib is required.

Clinical studies have shown that high doses of erlotinib have caused maternal toxicity and fetal death in rabbits. Although no controlled studies were made on pregnant women, the use of erlotinib on pregnant women should be avoided, or at least given extreme caution. The potential benefits must be weighed against the risks. Women who are pregnant, or planning to become must consult their physician prior to taking erlotinib. Nursing mothers planning to take erlotinib must first consult their physicians. Although no studies have shown that erlotinib is excreted in human milk, caution is to be exercised as many drugs have been studied to pass onto breast milk.

Erlotinib has the following structural formula:

Chemical structure of erlotinib

• Molecular formula of erlotinib is C22H23N3O4
• Chemical IUPAC Name is N-(3-ethynylphenyl)-6,7-bis(2-methoxyethoxy)quinazolin-4-amine
• Molecular weight is 393.436 g/mol
Erlotinib available : 25mg tablets, 100mg tablets and 150mg tablets

Brand name(s): Tarceva

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