Toremifene Citrate

Description

11 DESCRIPTION FARESTON (toremifene citrate) Tablets for oral administration each contain 88.5 mg of toremifene citrate, which is equivalent to 60 mg toremifene. FARESTON is an estrogen agonist/antagonist. The chemical name of toremifene is: 2-{p-[(Z)-4-chloro-1,2-diphenyl-1-butenyl]phenoxy}-N,N-dimethylethylamine citrate (1:1). The structural formula is: and the molecular formula is C 26 H 28 ClNO

What Is Toremifene Citrate Used For?

1 INDICATIONS AND USAGE FARESTON® is an estrogen agonist/antagonist indicated for the treatment of metastatic breast cancer in postmenopausal women with estrogen-receptor positive or unknown tumors. FARESTON® is an estrogen agonist/antagonist indicated for the treatment of metastatic breast cancer in postmenopausal women with estrogen-receptor positive or unknown tumors. ( 1 )

Dosage and Administration

2 DOSAGE AND ADMINISTRATION The dosage of FARESTON is 60 mg, once daily, orally. Treatment is generally continued until disease progression is observed. 60 mg once daily, orally ( 2 )

Side Effects (Adverse Reactions)

6 ADVERSE REACTIONS Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice. Most common adverse reactions are hot flashes, sweating, nausea and vaginal discharge. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Kyowa Kirin, Inc. at 1-800-305-FARESTON (1-800-305-3273) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Trials Experience Adverse drug reactions are principally due to the antiestrogenic actions of FARESTON and typically occur at the beginning of treatment. The incidences of the following eight clinical toxicities were prospectively assessed in the North American Study. The incidence reflects the toxicities that were considered by the investigator to be drug related or possibly drug related. North American Study FAR60 TAM20 n = 221 n = 215 Hot Flashes 35% 30% Sweating 20% 17% Nausea 14% 15% Vaginal Discharge 13% 16% Dizziness 9% 7% Edema 5% 5% Vomiting 4% 2% Vaginal Bleeding 2% 4% Approximately 1% of patients receiving FARESTON (n = 592) in the three controlled studies discontinued treatment as a result of adverse reactions (nausea and vomiting, fatigue, thrombophlebitis, depression, lethargy, anorexia, ischemic attack, arthritis, pulmonary embolism, and myocardial infarction). Serious adverse reactions occurring in at least 1% of patients receiving FARESTON in the three major trials are listed in the table below. Three prospective, randomized, controlled clinical studies (North American, Eastern European, and Nordic) were conducted. The patients were randomized to parallel groups receiving FARESTON 60 mg (FAR60) or tamoxifen 20 mg (TAM20) in the North American Study or tamoxifen 40 mg (TAM40) in the Eastern European and Nordic studies. The North American and Eastern European studies also included high-dose toremifene arms of 200 and 240 mg daily, respectively [see Clinical Studies (14) ] . * Most of the ocular abnormalities were observed in the North American Study in which on-study and biannual ophthalmic examinations were performed. No cases of retinopathy were observed in any arm. ** Elevated defined as follows: North American Study: AST >100 IU/L; alkaline phosphatase >200 IU/L; bilirubin > 2 mg/dL. Eastern European and Nordic studies: AST, alkaline phosphatase, and bilirubin - WHO Grade 1 (1.25 times the upper limit of normal). Adverse Reactions North American Eastern European Nordic FAR60 TAM20 FAR60 TAM40 FAR60 TAM40 n=221(%) n=215(%) n=157(%) n=149(%) n=214(%) n=201(%) Cardiac Cardiac Failure 2 (1) 1 (<1) - 1 (<1) 2 (1) 3 (1.5) Myocardial Infarction 2 (1) 3 (1.5) 1 (<1) 2 (1) - 1 (<1) Arrhythmia - - - - 3 (1.5) 1 (<1) Angina Pectoris - - 1 (<1) - 1 (<1) 2 (1) Ocular* Cataracts 22 (10) 16 (7.5) - - - 5 (3) Dry Eyes 20 (9) 16 (7.5) - - - - Abnormal Visual Fields 8 (4) 10 (5) - - - 1 (<1) Corneal Keratopathy 4 (2) 2 (1) - - - - Glaucoma 3 (1.5) 2 (1) 1 (<1) - - 1 (<1) Abnormal Vision/Diplopia - - - - 3 (1.5) - Thromboembolic Pulmonary Embolism 4 (2) 2 (1) 1 (<1) - - 1 (<1) Thrombophlebitis - 2 (1) 1 (<1) 1 (<1) 4 (2) 3 (1.5) Thrombosis - 1 (<1) 1 (<1) - 3 (1.5) 4 (2) CVA/TIA 1 (<1) - - 1 (<1) 4 (2) 4 (2) Elevated Liver Tests** AST 11 (5) 4 (2) 30 (19) 22 (15) 32 (15) 35 (17) Alkaline Phosphatase 41 (19) 24 (11) 16 (10) 13 (9) 18 (8) 31 (15) Bilirubin 3 (1.5) 4 (2) 2 (1) 1 (<1) 2 (1) 3 (1.5) Hypercalcemia 6 (3) 6 (3) 1 (<1) - - - Other adverse reactions included leukopenia and thrombocytopenia, skin discoloration or dermatitis, constipation, dyspnea, paresis, tremor, vertigo, pruritus, anorexia, reversible corneal opacity (corneal verticulata), asthenia, alopecia, depression, jaundice, and rigors. The incidence of AST elevations was greater in the 200 and 240 mg FARESTON dose arms than in the tamoxifen arms. Higher doses of FARESTON were also associated with an increase in...

Drug Interactions

7 DRUG INTERACTIONS Drugs that decrease renal calcium excretion, e.g., thiazide diuretics, may increase the risk of hypercalcemia in patients receiving FARESTON. ( 7.1 ) Agents that prolong QT should be avoided. ( 7.2 ) Coadministration with a strong CYP3A4 inducer may result in a relevant decrease in FARESTON exposure and should be avoided. ( 7.3 ) Coadministration with a strong CYP3A4 inhibitor can result in a relevant increase in FARESTON exposure and should be avoided. ( 7.4 ) CYP2C9 substrates with a narrow therapeutic index such as warfarin or phenytoin with FARESTON should be used with caution and require careful monitoring. ( 7.6 ) 7.1 Drugs that Decrease Renal Calcium Excretion Drugs that decrease renal calcium excretion, e.g., thiazide diuretics, may increase the risk of hypercalcemia in patients receiving FARESTON. 7.2 Agents that Prolong QT The administration of FARESTON with agents that have demonstrated QT prolongation as one of their pharmacodynamic effects should be avoided. Should treatment with any of these agents be required, it is recommended that therapy with FARESTON be interrupted. If interruption of treatment with FARESTON is not possible, patients who require treatment with a drug that prolongs QT should be closely monitored for prolongation of the QT interval. Agents generally accepted to prolong QT interval include Class 1A (e.g., quinidine, procainamide, disopyramide) and Class III (e.g., amiodarone, sotalol, ibutilide, dofetilide) antiarrhythmics; certain antipsychotics (e.g., thioridazine, haloperidol); certain antidepressants (e.g., venlafaxine, amitriptyline); certain antibiotics (e.g., erythromycin, clarithromycin, levofloxacin, ofloxacin); and certain anti-emetics (e.g., ondansetron, granisetron). In patients at increased risk, electrocardiograms (ECGs) should be obtained and patients monitored as clinically indicated [see Boxed Warning and Warnings and Precautions (5.1) ] . 7.3 Effect of Strong CYP3A4 Inducers on Toremifene Strong CYP3A4 enzyme inducers, such as dexamethasone, phenytoin, carbamazepine, rifampin, rifabutin, phenobarbital, St. John's Wort, lower the steady-state concentration of toremifene in serum. 7.4 Effect of Strong CYP3A4 Inhibitors on Toremifene In a study of 18 healthy subjects, 80 mg toremifene once daily coadministered with 200 mg of ketoconazole twice daily increased the toremifene Cmax and AUC by 1.4- and 2.9-fold, respectively. N-demethyltoremifene Cmax and AUC were reduced by 56% and 20%, respectively. The administration of FARESTON with agents that are strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, clarithromycin, atazanavir, indinavir, nefazodone, nelfinavir, ritonavir, saquinavir, telithromycin, and voriconazole) increase the steady-state concentration in serum and should be avoided. Grapefruit juice may also increase plasma concentrations of toremifene and should be avoided. Should treatment with any of these agents be required, it is recommended that therapy with...

Contraindications

4 CONTRAINDICATIONS Hypersensitivity to the drug ( 4.1 ) QT Prolongation, Hypokalemia, Hypomagnesemia ( 4.2 ) 4.1 Hypersensitivity to the Drug FARESTON is contraindicated in patients with known hypersensitivity to the drug. 4.2 QT Prolongation, Hypokalemia, Hypomagnesemia Toremifene should not be prescribed to patients with congenital/acquired QT prolongation (long QT syndrome), uncorrected hypokalemia, or uncorrected hypomagnesemia.

Pregnancy and Breastfeeding

8.1 Pregnancy Pregnancy Category D [see Warnings and Precautions (5.7) .] Based on its mechanism of action in humans and findings of increased pregnancy loss and fetal malformation in animal studies, FARESTON can cause fetal harm when administered to a pregnant woman. Toremifene caused embryo-fetal toxicities at maternal doses that were lower than the 60 mg daily recommended human dose on a mg/m 2 basis. There are no adequate and well-controlled studies in pregnant women using FARESTON. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to the fetus. In animal studies, toremifene crossed the placenta and accumulated in the rodent fetus. Administration of toremifene to pregnant rats during organogenesis at doses of approximately 6% the daily maximum recommended human dose of 60 mg (on a mg/m 2 basis) resulted in signs of maternal toxicity and increased preimplantation loss, increased resorptions, reduced fetal weight, and fetal anomalies. Fetal anomalies include malformation of limbs, incomplete ossification, misshapen bones, ribs/spine anomalies, hydroureter, hydronephrosis, testicular displacement, and subcutaneous edema. Maternal toxicity may have contributed to these adverse embryo-fetal effects. Similar embryo-fetal toxicities occurred in rabbits that received toremifene at doses approximately 40% the daily recommended human dose of 60 mg (on a mg/m 2 basis). Findings in rabbits included increased preimplantation loss, increased resorptions, and fetal anomalies, including incomplete ossification and anencephaly. Animal doses resulting in embryo-fetal toxicities were ≥1.0 mg/kg/day in rats and ≥1.25 mg/kg/day in rabbits. In rodent models of fetal reproductive tract development, toremifene produced inhibition of uterine development in female pups similar to effects seen with diethylstilbestrol (DES) and tamoxifen. The clinical relevance of these changes is not...

8.2 Nursing Mothers It is not known if toremifene is excreted in human milk. Toremifene is excreted in the milk of lactating rats. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants from FARESTON, a decision should be made to either discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.

Overdosage

10 OVERDOSAGE Lethality was observed in rats following single oral doses that were ≥1000 mg/kg (about 150 times the recommended human dose on a mg/m 2 basis) and was associated with gastric atony/dilatation leading to interference with digestion and adrenal enlargement. Vertigo, headache, and dizziness were observed in healthy volunteer studies at a daily dose of 680 mg for 5 days. The symptoms occurred in two of the five subjects during the third day of the treatment and disappeared within 2 days of discontinuation of the drug. No immediate concomitant changes in any measured clinical chemistry parameters were found. In a study in postmenopausal breast cancer patients, toremifene 400 mg/m 2 /day caused dose-limiting nausea, vomiting, and dizziness, as well as reversible hallucinations and ataxia in one patient. Theoretically, overdose may be manifested as an increase of antiestrogenic effects, such as hot flashes; estrogenic effects, such as vaginal bleeding; or nervous system disorders, such as vertigo, dizziness, ataxia, and nausea. There is no specific antidote and the treatment is symptomatic.

How Supplied

16 SUPPLIED/STORAGE AND HANDLING FARESTON Tablets, containing toremifene citrate in an amount equivalent to 60 mg of toremifene, are round, convex, unscored, uncoated, and white, or almost white. FARESTON Tablets are identified with TO 60 embossed on one side. FARESTON Tablets are available as: NDC 42747-327-30 bottles of 30 NDC 42747-327-72 samples of 7 Store at 25°C (77°F). Excursions permitted to 15-30°C (59-86°F) [See USP Controlled Room Temperature.] Protect from heat and light.