Toremifene is a first generation selective estrogen receptor modulator (SERM). Like TAMOXIFEN, it is an estrogen agonist for bone tissue and cholesterol metabolism but is antagonistic on mammary and uterine tissue.
Toremifene is an Estrogen Agonist/Antagonist. The mechanism of action of toremifene is as a Selective Estrogen Receptor Modulator.
Toremifene is a nonsteroidal triphenylethylene antiestrogen. Chemically related to tamoxifen, toremifene is a selective estrogen receptor modulator (SERM). This agent binds competitively to estrogen receptors, thereby interfering with estrogen activity. Toremifene also has intrinsic estrogenic properties, which are manifested according to tissue type or species. (NCI04).
Mechanism of Action of Toremifene
Toremifene is a nonsteroidal triphenylethylene derivative. Toremifene binds to estrogen receptors and may exert estrogenic, antiestrogenic, or both activities, depending upon the duration of treatment, animal species, gender, target organ, or endpoint selected. The antitumor effect of toremifene in breast cancer is believed to be mainly due to its antiestrogenic effects, in other words, its ability to compete with estrogen for binding sites in cancer, blocking the growth-stimulating effects of estrogen in the tumor. Toremifene may also inhibit tumor growth through other mechanisms, such as induction of apoptosis, regulation of oncogene expression, and growth factors.
Indications of Toremifene
- For the treatment of metastatic breast cancer in postmenopausal women with estrogen receptor-positive or receptor-unknown tumors.
- Toremifene is currently under investigation as a preventative agent for prostate cancer in men with high-grade prostatic intraepithelial neoplasia and no evidence of prostate cancer.
- Breast Cancer
- Breast Cancer, Metastatic
- Desmoid Tumors
- Metastatic Breast Cancer
Contraindications of Toremifene
- Low amount of magnesium in the blood
- High amount of calcium in the blood
- Low amount of potassium in the blood
- Decreased blood platelets
- Decreased white blood cells
- Very rapid heartbeat – torsades de pointes
- Prolonged QT interval on EKG
- Abnormal EKG with QT changes from birth
- Obstruction of a blood vessel by a blood clot
- Overgrowth of the Uterine Lining
- Pregnancy
- A mother who is producing milk and breastfeeding
- Allergies to Tamoxifen Analogues
Dosage of Toremifene
Strengths: 60 mg
Breast Cancer
- 60 mg orally once daily
- Duration of therapy: Treatment is generally continued until disease progression is observed.
Side Effects of Toremifene
The Most Common
- confusion or disorientation
- Blindness
- decreased vision
- dry eyes
- feeling of warmth
- redness of the face, neck, arms, and occasionally, the upper chest
- sudden sweating
- sweating
- diarrhea
- heartburn
- severe nausea or vomiting
- signs of anemia (low red blood cells; e.g., pale skin, unusual tiredness or weakness)
- signs of bleeding (e.g., unusual bruising or bleeding, pinpoint red spots on skin, black tarry stools, bloody nose, blood in urine, coughing blood, cuts that don’t stop bleeding)
- signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
More Common
- Diarrhea
- heartburn
- sores in mouth and on lips
- Black, tarry stools
- cough or hoarseness, accompanied by fever or chills
- fever or chills
- lower back or side pain, accompanied by fever or chills
- nausea and vomiting (severe)
- painful or difficult urination, accompanied by fever or chills
- stomach cramps
Rare
- change in vaginal discharge
- changes in skin color
- changes in vision
- changes in weight
- chest pain, discomfort, tightness, or heaviness
- confusion
- constipation
- cough
- depression
- dilated neck veins
- dizziness, lightheadedness
- dry mouth
- fainting
- fast, slow, or irregular heartbeat
- inability to speak, incoherent speech
- irregular breathing
- loss of appetite
Drug Interactions of Toremifene
Toremifene may interact with following drugs, supplements & may change the efficacy of the drug
- celecoxib
- dapsone
- echinacea
- fluoxetine
- ganciclovir
- glipizide
- glyburide
- interferon
- ketamine
- leflunomide
- leucovorin
- levamisole
- live vaccines (e.g., BCG, yellow fever)
- losartan
- montelukast
- nateglinide
- other cancer medications (including but not limited to cytarabine, flucytosine, methotrexate)
- pimecrolimus
- phenytoin
- sulfamethoxazole
- tacrolimus
- tamoxifen
- tolbutamide
- trimethoprim
- voriconazole
- warfarin
- zafirlukast
Pregnancy Category
AU TGA Pregnancy Category: B3
US FDA Pregnancy Category: D
Pregnancy:
There is a possibility of birth defects if toremifene is being used at the time of conception, or if it is taken during pregnancy. Use effective birth control while you are being treated with this medication. If you become pregnant while taking this medication, contact your doctor immediately.
Lactation
It is not known if toremifene passes into breast milk. Due to the potential for serious harm to the baby, women receiving fluorouracil should not breast-feed.
