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What is erlotinib, and how does it work (mechanism of action)?
Erlotinib is a synthetic (man-made) oral drug that is used for treating cancer. It is approved for treatment of non-small cell lung cancer (NSCLC).
There are more than 1.2 million cases worldwide of lung cancer each year, causing one death every 3 seconds. According to the National Cancer Institute, lung cancer is responsible for nearly 30% of cancer deaths in the US. NSCLC is the most common form of lung cancer and accounts for almost 80% of all the cases.
Many cells, including cancer cells, have receptors on their surfaces for epidermal growth factor (EGF), a protein that is normally produced by the body and that promotes the growth and multiplication of cells. When EGF attaches to epidermal growth factor receptors (EGFRs), it causes an enzyme called tyrosine kinase to become active within the cells. Tyrosine kinase triggers chemical processes that cause the cells, including cancer cells, to grow, multiply, and spread. Erlotinib attaches to EGFRs, blocking the attachment of EGF and the activation of tyrosine kinase. This mechanism for stopping cancer cells from growing and multiplying is very different from the mechanisms of chemotherapy and hormonal therapy. Erlotinib was approved by the FDA in November of 2004.
What brand names are available for erlotinib?
Tarceva
Do I need a prescription for erlotinib?
Yes
What are the uses for erlotinib?
Erlotinib is prescribed for the treatment of non-small cell lung cancer, advanced unresectable metastatic prostate cancer, and for pancreatic cancer.
What are the side effects of erlotinib?
The most common side effects of erlotinib are:
- rash,
- diarrhea,
- loss of appetite,
- weight loss,
- nausea,
- vomiting,
- stomach pain,
- fatigue,
- shortness of breath,
- mouth sores,
- dry skin,
- itching, and
- cough.
Any of these can occur in about half of all patients who receive the medicine, but these effects are usually mild. There have been rare reports of serious lung disease, including deaths, in patients receiving erlotinib for treatment of NSCLC or other tumors.
Other important side effects include:
- Liver failure,
- kidney failure,
- increased bleeding rates,
- gastrointestinal perforation, and
- corneal perforation or ulceration.
What is the dosage for erlotinib?
The usual dose of erlotinib is 150 mg daily for NSCLC and 100 mg daily for pancreatic cancer. Erlotinib should be taken on an empty stomach at least one hour before or two hours after eating because food may reduce the absorption of erlotinib.
Which drugs or supplements interact with erlotinib?
CYP3A4 is an enzyme in the liver that breaks-down and helps to eliminate erlotinib from the body. Drugs that inhibit CYP3A4 can result in high levels of erlotinib in the body, and the high levels can result in toxicity from erlotinib. Such drugs include atazanavir (Reyataz), clarithromycin (Biaxin), indinavir (Crixivan), itraconazole (Sporanox), ketoconazole (Nizoral), nefazodone (Serzone), nelfinavir (Viracept), ritonavir (Norvir), saquinavir (Invirase; Fortovase), telithromycin (Ketek), and voriconazole (VFEND). In patients receiving these drugs, a lower dose of erlotinib may be needed to prevent toxicity.
Some drugs increase the elimination of erlotinib by increasing the activity of CYP3A4 enzymes. This reduces the levels of erlotinib in the body and may reduce its effect. Examples of such drugs include rifampicin (Rifadin), rifabutin (Mycobutin), rifapentine (Priftin), phenytoin (Dilantin), carbamazepine (Tegretol), phenobarbital and St. John's Wort. These drugs should be avoided in patients taking erlotinib, if possible. If alternative drugs are not an option, higher doses of erlotinib may be required.
Cigarette smoking also reduces the concentration of erlotinib in the blood. Patients are advised to quit smoking.
Drugs that reduce the production of acid in the stomach will reduce the absorption of erlotinib. Therefore, proton pump inhibitors (PPI's, for example, omeprazole [Prilosec, Zegerid]) should not be administered with erlotinib, and erlotinib should be administered 10 hours before H2-receptor blockers (for example, ranitidine [Zantac]) or two hours after taking the H2-receptor blocker.
Administration of antacids should be separated from administration of erlotinib by several hours.
Erlotinib has been associated with increased risk of bleeding, especially in patients also taking warfarin (Coumadin). Patients taking warfarin should be monitored closely.
Is erlotinib safe to take if I’m pregnant or breastfeeding?
Erlotinib has been shown to cause maternal toxicity and fetal death in rabbits given high doses of erlotinib. Even though there are no well-controlled studies in pregnant women using erlotinib, women of childbearing age should be advised to avoid pregnancy while on erlotinib.
It is not known whether erlotinib is excreted in human milk. Because many medicines are excreted in human milk and because the effects of erlotinib on infants have not been studied, women should abstain from breastfeeding while receiving erlotinib.
What else should I know about erlotinib?
What preparations of erlotinib are available?
Tablets: 25, 100, and 150 mg
How should I keep erlotinib stored?
Erlotinib should be stored at room temperature, 15 C – 30 C (59 F – 86 F).