Name of the oestrogen Receptor Modulators
- Raloxifene
- Toremifene
Therapeutic Action
The desired and beneficial actions of depolarizing estrogen receptor modulator are:
- To produce some of the positive effects of estrogen replacement while limiting the adverse effects.
- To increase bone mineral density without stimulating the endometrium.
| RALOXIFENE |
| Availability: Tablets: 60 mg. |
| Administration/handling: PO: Give without regard to food. |
| Discontinue at least 72 hrs prior to and during prolonged immobilization (may increase risk for DVT/PE). |
| Treatment and prevention of osteoporosis in postmenopausal women; reduction of invasive breast cancer risk in postmenopausal women with osteoporosis; reduction of invasive breast cancer risk in postmenopausal women at high risk for invasive breast cancer : Adults: 60 mg P.O. daily |
Mechanism of Action:
Selective estrogen receptor modulator (SERM) that binds to estrogen receptors, increasing bone mineral density.
Blocks estrogen effects in breast/uterus.
Therapeutic Effect: Reduces bone resorption, increases bone mineral density, reduces incidence of fractures.
Indications:
- Prevention/treatment of osteoporosis in postmenopausal women.
- Reduces risk of invasive breast cancer in postmenopausal women with osteoporosis and postmenopausal women at high risk for invasive breast cancer.
Off-label uses
- Prophylaxis of cardiovascular disease
Contraindications & Cautions:
- Hypersensitivity to raloxifene.
- Active or history of venous thromboembolic events, such as deep vein thrombosis (DVT), pulmonary embolism, retinal vein thrombosis
- Women who are or may become pregnant
- Breastfeeding.
Cautions:
Cardiovascular disease, renal/hepatic impairment, risk for venous thromboembolism, unexplained uterine bleeding, elevated triglycerides in response to oral estrogen therapy.
Metabolism and Half- Life:
- Rapidly absorbed after PO administration.
- Protein binding: 95%. Metabolized in liver. Excreted primarily in feces.
- Unknown if removed by hemodialysis. Half-life: 27.7–32.5 hrs.
Drug Interactions:
- Bile acid sequestrants (e.g. Cholestyramine) may decrease absorption/ effect.
- May decrease absorption of levothyroxine.
- May lower serum total cholesterol, LDL.
- May decrease platelet count, serum inorganic phosphate, albumin, calcium, protein.
Side –Effects:
- Frequent: Hot flashes, flu-like symptoms, arthralgia, sinusitis.
- Occasional: Weight gain, nausea, myalgia, pharyngitis, cough, dyspepsia, leg cramps, rash, depression.
- Rare: Vaginitis, UTI, peripheral edema, flatulence, vomiting, fever, migraine, diaphoresis.
Nursing Considerations
Baseline assessment
- Question history of thrombosis (CVA, DVT, PE).
- Question for possibility of pregnancy.
- Drug should be discontinued 72 hrs before and during prolonged immobilization (postop recovery, prolonged bed rest). Therapy may be resumed only after pt is fully ambulatory.
- Determine serum total, LDL cholesterol before therapy and routinely thereafter.
Intervention/evaluation
- Monitor serum total cholesterol, total calcium, inorganic phosphate, total protein, albumin, bone mineral density, platelet count.
- Diligently monitor for CVA (aphasia, blindness, confusion, paresthesia, hemiparesis, syncope), DVT (arm/leg pain, swelling), pulmonary embolism (chest pain, dyspnea, hypoxia, tachycardia).
- Watch for thromboembolic events, especially during first 4 months of therapy.
- Stay alert for other adverse effects, particularly leg cramps, other musculoskeletal complaints, and respiratory disorders.
- Assess bone mineral density test results.
- Monitor for unexplained vaginal bleeding
Patient/family teaching
- Avoid prolonged restriction of movement during travel (increased risk of venous thromboembolic events).
- Take supplemental calcium, vitamin D if daily dietary intake is inadequate.
- Engage in regular weight-bearing exercise.
- Modify, discontinue habits of cigarette smoking, alcohol consumption.
- Report symptoms of DVT (swelling, pain, hot feeling in the arms or legs), lung embolism (difficulty breathing, chest pain, rapid heart rate), stroke (blindness, confusion, difficulty speaking, one-sided weakness, passing out).
- Tell patient she may take with or without food.
- Instruct patient to read package insert before starting drug and then periodically.
- Teach patient to recognize and immediately report symptoms of blood clots.
- Instruct patient to stop taking drug 3 days before anticipated period of prolonged immobility, and to restart it only after she regains normal mobility.
- Tell patient that drug may cause hot flashes, but that these are normal effects.
- Advise patient to report unexplained vaginal bleeding or leg cramps
| TOREMIFENE |
| Availability: tablet: 60mg |
| Administration and handling: Administer orally without regard to meals. Toremifene should be stored at room temperature, between 68 F to 77 F (20 C to 25 C) |
| Breast Cancer: 60 mg PO qDay until disease progresses. Monitor patients on warfarin for increased PT |
Mechanism of Action:
Selective estrogen receptor modulator: nonsteroidal estrogen, agonist/antagonist, competes for estrogen binding sites on breast tumor cells
Indications:
- Breast Cancer
- Estrogen-receptor positive or unknown metastatic breast cancer in postmenopausal women
Contraindications & Cautions:
- Hypersensitivity
- Estrogen receptor-negative tumors
- Thromboembolic history
- Should not be prescribed to patients with congenital/acquired QT prolongation, uncorrected hypokalemia or uncorrected hypomagnesemia
Use with caution in:
Hypercalcemia and Tumor Flare, Hepatotoxicity, Prolongation of the QT Interval, patients at high risk of endometrial cancer.
Metabolism and Half- Life:
- Half-Life: 5 days
- Peak Plasma Time: 3 hr
- Protein Bound: >99.5%
- Metabolism: Hepatic CYP3A4
- Excretion: Feces (primarily); urine (10%)
Drug Interactions:
- Drugs that decrease renal calcium excretion, e.g., thiazide diuretics, may increase the risk of hypercalcemia in patients receiving toremifene citrate.
- Antifungals, azoles (e.g., ketoconazole)- Possible increased toremifene concentrations
- Anticonvulsants (e.g., carbamazepine, clonazepam, phenobarbital, phenytoin) – Possible decreased toremifene concentrations (due to increased clearance and decreased elimination half-life of toremifene)
- Anticoagulants, oral (e.g., warfarin)- Possible increased PT
Prolongs QTc interval in a dose- and concentration-related manner
- QT prolongation can result in Torsade de pointes, which may result in syncope, seizure, and/or death
- Should not be prescribed to patients with congenital/acquired QT prolongation, uncorrected hypokalemia or uncorrected hypomagnesemia
- Drugs known to prolong QT interval and strong CYP3A4 inhibitors should be avoided
Side- Effects:
- Sweating, hot flashes
- Nausea
- Vaginal discharge.
- Cataracts
- Dizziness
- Edema
- Vomiting
- Dry eyes
- Hypercalcemia
- Thrombophlebitis
- Vaginal bleeding
- Corneal opacity
Nursing Considerations
- Assess for the mentioned cautions and contraindications (e.g. drug allergies, cardiovascular diseases, metabolic bone disease, history of thromboembolism, etc.) to prevent any untoward complications.
- Perform a thorough physical assessment (e.g. bowel sounds, skin assessment, vital signs, mental status, etc.) to establish baseline data before drug therapy begins, to determine effectiveness of therapy, and to evaluate for occurrence of any adverse effects associated with drug therapy.
- Assist with pelvic and breast examinations. Ensure specimen collection for Pap smear and obtain a history of patient’s menstrual cycle to provide baseline data and to monitor for any adverse effects that could occur.
- Arrange for ophthalmic examination especially for patients who are wearing contact lenses because hormonal changes can alter the fluid in the eye and curvature of the cornea, which can change the fit of contact lenses and alter visual acuity.
- Monitor laboratory test results (e.g. urinalysis, renal and hepatic function tests, etc.) to determine possible need for a reduction in dose and evaluate for toxicity.
Intervention/ evaluation
- Administer drug with food to prevent GI upset.
- Provide analgesic for relief of headache as appropriate.
- Provide small, frequent meals to assist with nausea and vomiting.
- Monitor for swelling and changes in vision or fit of contact lenses to monitor for fluid retention and fluid changes.
- Provide comfort measures to help patient tolerate drug effects.
- Provide safety measures (e.g. adequate lighting, raised side rails, etc.) to prevent injuries.
- Educate client on drug therapy to promote understanding and compliance.
- Monitor patient response to therapy (palliation of signs and symptoms of menopause, prevention of pregnancy, decreased risk factors for coronary artery disease, and palliation of certain cancers).
- Monitor for adverse effects (e.g. GI upset, edema, changes in secondary sex characteristics, headaches, thromboembolic episodes, and breakthrough bleeding).
- Evaluate patient understanding on drug therapy by asking patient to name the drug, its indication, and adverse effects to watch for.
- Monitor patient compliance to drug therapy.
REFERENCES
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