Estrogen (hormone replacement therapy)

Estradiol

Estrace

Dosage form
Tablet
Available strengths
0.5 mg, 1 mg, 2 mg
Drug class
Estrogen (hormone replacement therapy)
Common brand
Estrace

Clinical overview. Estradiol is an estrogen hormone replacement medication used to relieve menopausal symptoms such as hot flashes and vaginal dryness, and to help prevent osteoporosis after menopause. It is taken as a daily oral tablet, and women who still have a uterus generally need a progestin added to protect against uterine cancer. Estradiol carries increased risks of blood clots, stroke, and certain cancers, so it is used at the lowest effective dose for the shortest necessary time.

Indication

Common therapeutic uses

  • Estradiol is used for symptomatic relief of menopausal symptoms such as hot flushes and vaginal dryness, itching, or burning.
  • Estradiol may help prevent osteoporosis in women with estrogen deficiency from natural or surgical menopause, when combined with adequate diet, calcium and vitamin D intake, smoking cessation, and weight-bearing exercise.
  • In women who still have a uterus, estradiol should always be combined with a progestin given on a cyclic schedule to reduce the risk of overgrowth of the uterine lining.

Pregnancy

Risk assessment and monitoring considerations

Contraindicated in pregnancy. Confirm pregnancy status and discuss alternative therapy with the prescriber before dispensing.

  • Estradiol is contraindicated in known or suspected pregnancy; estrogens are not indicated for use during pregnancy.

Breastfeeding

Infant exposure considerations

  • Estradiol is contraindicated during breastfeeding.

Geriatrics

Dosing and tolerability considerations

  • Use of combined estrogen plus progestin therapy in women aged 65 and older may increase the risk of developing probable dementia.
  • Evidence suggests use in the geriatric population may be associated with differences in safety or effectiveness compared with younger patients.

Pediatrics

Use in children and adolescents

  • Estradiol has not been studied in patients under 18 years of age, and no pediatric indication has been authorized.

Dosage & Administration

Practical dosing and administration

  • For menopausal symptoms, treatment is usually started with 1 mg once daily, adjusted afterward to the individual's needs; tapering or stopping should be attempted at 3- to 6-month intervals.
  • For prevention of osteoporosis, treatment is usually started with 0.5 mg once daily as soon as possible after menopause, and the dose may be adjusted based on clinical response.
  • In women who still have a uterus, estrogen is generally given for the first 21 to 25 days of each month, with a progestin added for the last 12 to 14 days of that cycle to protect the uterine lining; women who have had a hysterectomy can take estrogen continuously every day.
  • The lowest effective dose should be used, and estradiol should be prescribed at the lowest dose and for the shortest duration appropriate for the condition being treated.
  • If a dose is missed, it should be taken as soon as remembered unless it is almost time for the next dose, in which case the missed dose should be skipped; doses should not be doubled.

Overdose

Recognizing and responding to overdose

If overdose is suspected, seek emergency medical attention immediately or contact your regional Poison Control Centre without delay.

  • Reports of large overdoses of estrogen products, including in young children, have not shown serious acute effects.
  • Overdose in women may cause nausea, breast discomfort, fluid retention, bloating, or vaginal bleeding.
  • Treatment involves removing unabsorbed drug from the stomach by gastric lavage and providing symptomatic care.

Common side effects

Frequently reported tolerability concerns

  • Nausea may occur.
  • Bloating or abdominal cramps may occur.
  • Breast pain, tenderness, or swelling may occur.
  • Headache may occur.
  • Nervousness or irritability may occur.
  • Weight or appetite changes may occur.
  • Vaginal bleeding, spotting, or discharge may occur.
  • Acne may occur.
  • Dark patches of facial skin (melasma) may occur.
  • Hair loss or abnormal hair growth may occur.
  • Fatigue may occur.

Serious side effects

Findings that may require urgent assessment

Serious side effects require immediate discussion with the prescriber or emergency care.

  • Combined estrogen plus progestin therapy increases the risk of heart attack, stroke, invasive breast cancer, and blood clots in the lungs or legs.
  • Estrogen-alone therapy increases the risk of stroke and blood clots in the veins.
  • Unopposed estrogen in women who still have a uterus increases the risk of overgrowth of the uterine lining and uterine cancer.
  • Long-term hormone replacement therapy use of five years or more has been associated with an increased risk of ovarian cancer.
  • Combined estrogen plus progestin therapy in women 65 and older may increase the risk of probable dementia.
  • The risk of gallbladder disease requiring surgery is increased with estrogen use.
  • Blood clots in the eye can cause sudden partial or complete vision loss.
  • Liver problems, including jaundice, may occur.
  • Pre-existing uterine fibroids may grow larger during estrogen therapy.
  • Seek urgent medical attention for chest pain, sudden shortness of breath, leg swelling or pain, sudden vision changes, sudden severe headache, or signs of a stroke.

Use with caution

Situations requiring closer assessment

  • Use with caution in women with a personal or family history of breast disease, abnormal mammograms, or breast biopsies.
  • Use with caution in women with a history or risk factors for blood clots, including obesity, smoking, or prolonged immobility.
  • Use with caution in women with high blood pressure, since estrogen therapy can raise blood pressure further.
  • Use with caution in women with diabetes or a predisposition to diabetes, since estrogen can worsen blood sugar and lipid control.
  • Use with caution in women with a history of liver or gallbladder disease.
  • Use with caution in women with epilepsy, asthma, or kidney disease, since fluid retention from estrogen may worsen these conditions.
  • Use with caution in women with high triglycerides or a family history of high blood fats, since estrogen can raise triglyceride levels.
  • Use with caution in women with a history of migraine, since estrogen may trigger or worsen migraine episodes.
  • Estrogens should be discontinued at least 4 weeks before major surgery associated with an increased risk of blood clots.

Contraindications

Situations where therapy may be inappropriate

  • Contraindicated in liver dysfunction or disease until liver function tests return to normal.
  • Contraindicated in known or suspected estrogen-dependent cancers, such as endometrial cancer.
  • Contraindicated in endometrial hyperplasia.
  • Contraindicated in known, suspected, or past history of breast cancer.
  • Contraindicated in undiagnosed abnormal genital bleeding.
  • Contraindicated in known or suspected pregnancy.
  • Contraindicated during breastfeeding.
  • Contraindicated in active or past history of blood clots in the arteries, such as stroke, heart attack, or coronary heart disease.
  • Contraindicated in classical migraine.
  • Contraindicated in active or past history of confirmed venous thromboembolism or active thrombophlebitis.
  • Contraindicated in partial or complete vision loss or double vision caused by blood vessel disease in the eye.
  • Contraindicated in patients with known hypersensitivity to estradiol or any ingredient in the product.

Drug interactions

Clinically relevant combinations

  • Estradiol may reduce the effectiveness of anticoagulants, antidiabetic drugs, and antihypertensive drugs.
  • Inducers of the CYP3A4 enzyme, such as St. John's Wort, phenobarbital, carbamazepine, and rifampin, may lower estrogen levels and reduce its effectiveness.
  • Inhibitors of CYP3A4, such as erythromycin, clarithromycin, ketoconazole, itraconazole, and ritonavir, may raise estrogen levels and increase the risk of side effects.
  • Other liver enzyme-inducing drugs, including barbiturates, hydantoins, meprobamate, and phenylbutazone, may reduce the effect of oral estrogens.
  • St. John's Wort and other over-the-counter herbal products may interfere with estrogen metabolism and alter its safety or effectiveness.
  • Estradiol can affect the results of certain thyroid and liver function tests, so laboratory staff should be informed that the patient is taking estrogen therapy.

Food interactions

Meal-related administration

  • Estradiol can be taken with or without food, though grapefruit juice may raise estrogen levels and should be used with caution.

Time of administration

Practical scheduling

  • Estradiol tablets are taken once daily at about the same time each day, with or without food.

Storage

Product handling

  • Store estradiol tablets at room temperature (15°C to 30°C), in a tightly closed container protected from light.

Patient take-away

Key counselling points for a quick closing summary

  • Estradiol should be used at the lowest effective dose for the shortest time needed to control symptoms.
  • Estrogen therapy is not intended to prevent heart disease or stroke.
  • Women who still have a uterus need a progestin added to their regimen to protect against uterine cancer.
  • Regular follow-up visits, including breast exams and mammograms, are recommended during treatment.
  • Report any unusual vaginal bleeding, breast lumps, or signs of blood clots to a healthcare professional promptly.

References

Source material and product information

  1. Health Canada Product Monograph — Estradiol

For professional reference. Confirm patient-specific decisions against the current approved product monograph and applicable clinical guidance.

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