Fareston is a prescription drug approved by the Food and Drug Administration (FDA) in 1997 to delay the progression of metastatic, estrogen receptor-positive breast cancer in postmenopausal women. Fareston was developed from Tamoxifen to provide the same benefits with fewer side effects. It may also be prescribed in cases where it is not known whether or not the breast cancer is estrogen receptor-positive. Fareston is also known by its drug name, Toremifene.
Fareston may not be suitable for women of childbearing age. Fareston may not be appropriate for women who have a history of blood clotting problems. Fareston should not be prescribed for women with a personal or family history of certain heart conditions. Those conditions include congenital and acquired QT prolongation, uncorrected hypokalemia or uncorrected hypomagnesemia. In those people, Fareston may cause a type of fast heartbeat called ventricular tachycardia that may result in death. The risk for ventricular tachycardia may increase if you take diuretics (water pills) or experience vomiting, diarrhea or severe sweating.
About two-thirds of breast cancers are estrogen receptor-positive, meaning that they require estrogen in order to grow. Fareston is a member of a class of drugs called selective estrogen receptor modulators, or SERM, that provide hormone therapy to treat or help prevent receptor-positive breast cancer. Fareston is believed to work by reducing the effect of estrogen in estrogen receptor-positive breast cancers.
How do I take it?
Fareston is a pill taken orally once a day. It is best to take it at the same time each day. It does not matter whether you take it with food or not. However, you should not eat grapefruit or drink grapefruit juice while taking Fareston. Grapefruit may interact with Fareston and cause dangerous side effects.
While you are taking Fareston, your doctor may periodically order blood tests to check your blood cell counts, liver function and calcium levels.
Women of childbearing age should not handle or breathe dust from Fareston tablets.
Fareston is usually taken until breast cancer shows signs of progressing.
Always follow your doctor’s instructions exactly when taking Fareston.
Since Toremifene (Fareston) was derived from Tamoxifen, many clinical studies focused on comparing the results of the two drugs. In a study of 1,035 women published in 2004, Toremifene and Tamoxifen were found to have comparable results. Of those who took Toremifene, 72 percent remained disease-free, and 85 percent were still alive at the end of the five-year study period. Of those who took Tamoxifen, 69 percent remained disease-free, and 81 percent were still alive at the end of the five-year study period.
When you first begin taking Fareston, your tumor may grow before it begins to shrink. This may cause skin redness and musculoskeletal pain. The tumor will shrink after a few weeks of taking Fareston.
Common side effects of Toremifine include hot flashes, sweating, nausea, dizziness and dry eyes.
Fareston can increase your risk for stroke or heart problems. Call your doctor immediately if you experience pain or swelling in your legs, shortness of breath, coughing up blood, or sudden dizziness or confusion, loss of consciousness, difficulty walking or speaking, difficulty seeing in one or both eyes, or sudden tingling, weakness or numbness in your face, arm or leg, especially if the latter only occurs on one side of your body.
Fareston may contribute to the development of endometrial (uterine) cancer. While you are taking Fareston, notify your doctor immediately if you experience irregular vaginal bleeding, changes in your menstrual cycle, unusual vaginal discharge, or sensations of pain or pressure in your pelvic region.
Other serious side effects for which you should seek medical help include persistent nausea or vomiting, skin easily bruising or bleeding, dark urine, or yellowing of eyes or skin (jaundice).
Many drugs can cause allergic reactions which, in the most serious cases, can result in death. Seek immediate medical help if you experience signs of a severe allergic reaction such as difficulty breathing or swelling in the face, throat, eyes, lips or tongue.