Toremifene Citrate

Trade Names:
Fareston
- Oral tablets 60 mg

Pharmacology

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A nonsteroidal antiestrogen that blocks the growth-stimulating effects of estrogen in the tumor.

Pharmacokinetics

Absorption

Toremifene is well absorbed and is not influenced by food. T _max is 3 h. Steady state is reached in about 4 to 6 wk.

Distribution

Vd of toremifene is 580 L. Approximately 99.5% of the drug is bound to plasma proteins, mainly albumin. Mean distribution t _½ is approximately 4 h.

Metabolism

Toremifene is extensively metabolized, principally by CYP3A4 to N-demethyltoremifene.

Elimination

Mean total clearance is about 5 L/h. Elimination is primarily in feces (as metabolites) with about 10% excreted in urine during a 1-wk period. Elimination is slow. Toremifene t _½ is about 5 days.

Special Populations

The mean elimination t _½ was increased by less than 2-fold in patients with cirrhosis or fibrosis.

Increases of elimination t _½ and Vd were observed in elderly women.

Indications and Usage

Metastatic breast cancer in postmenopausal women.

Contraindications

Standard considerations.

Dosage and Administration

PO 60 mg once daily with or without food.

Storage/Stability

Store at room temperature. Protect from heat and light.

Drug Interactions

May increase toremifene clearance by 2-fold.

Toremifene may be altered by drugs that inhibit (eg, ketoconazole, itraconazole, macrolides) or induce (eg, phenobarbital, phenytoin, carbamazepine) this enzyme.

May cause hypercalcemia with agents that reduce renal excretion of calcium.

May increase the hypoprothrombinemic effect of warfarin.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Cardiovascular

Edema; pulmonary embolism; thrombophlebitis; thrombosis; cerebrovascular accident; transient ischemic attack; cardiac failure; MI.

CNS

Dizziness.

Endocrine

Hot flashes; sweating.

GI

Nausea and vomiting; elevated LFTs.

Genitourinary

Vaginal discharge; vaginal bleeding; endometrial thickening.

Metabolic

Hypercalcemia.

Musculoskeletal

Bone and tumor pain at initiation of therapy; soft tissue lesions can temporarily increase in size.

Special Senses

Cataracts; dry eyes; abnormal visual fields; corneal keratopathy; glaucoma; abnormal vision; diplopia.

Precautions

Pregnancy

Category D .

Lactation

Undetermined.

Children

Safety and efficacy not established.

Hepatic Function

Metabolized in the liver; dose reduction may be necessary in patients with liver disease.

Hypercalcemia and tumor flare

Drugs that decrease renal calcium excretion (eg, thiazide diuretics) may increase the risk of hypercalcemia in patients receiving toremifene.

Preexisting endometrial hyperplasia

Avoid long-term use.

Thromboembolic disease

Caution in patients with thromboembolic diseases.

Overdosage

Symptoms

Vertigo, headache, dizziness, nausea, vomiting, reversible hallucinations, ataxia.

Patient Information

• Instruct patient to contact the health care provider if vaginal bleeding occurs.
• Inform patient with bone metastases of typical signs/symptoms of hypercalcemia. Contact the health care provider if such signs or symptoms occur.

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