Omudhome Ogbru, PharmD
Omudhome Ogbru, PharmD
Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.
GENERIC NAME: erlotinib
BRAND NAME: Tarceva
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.
PREPARATIONS: Tablets: 25, 100, and 150 mg
STORAGE: Erlotinib should be stored at room temperature, 15-30 C (59-86 F).
PRESCRIBED FOR: Erlotinib is used for treatment of patients with metastatic or locally advanced non-small cell lung cancer (NSCLC) who have failed at least one previous round of chemotherapy. It also is used for maintenance of NSCLC that has not progressed after four cycles of platinum-based first line chemotherapy. Erlotinib is combined with gemcitabine to treat advanced unresectable metastatic prostate cancer and for pancreatic cancer.
DOSING: 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.
DRUG INTERACTIONS: 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.
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