1. Introduction
Oestrogen is a naturally occurring hormone that plays a vital role in the development and regulation of the female reproductive system and secondary sexual characteristics. In medicine, oestrogen is used as hormone replacement therapy (HRT) for menopausal symptoms, contraception, and in managing certain hormone-dependent conditions. Synthetic and natural oestrogen formulations are available for oral, transdermal, and vaginal administration.
2. Indications
- Hormone Replacement Therapy (HRT):
- Treatment of vasomotor symptoms (e.g., hot flushes, night sweats) associated with menopause.
- Prevention of postmenopausal osteoporosis.
- Management of hypoestrogenism (e.g., premature ovarian failure).
- Contraception (combined with progestin).
- Treatment of certain hormone-dependent cancers (e.g., advanced prostate cancer).
- Management of urogenital symptoms (e.g., vaginal dryness, atrophy).
- Gender-affirming hormone therapy for transgender women.
3. Dosage
Hormone Replacement Therapy (HRT):
- Oral tablets:
- 1–2 mg daily (e.g., estradiol).
- Transdermal patches:
- 25–100 mcg applied once or twice weekly.
- Vaginal cream/ring/tablet:
- Estradiol or conjugated oestrogens: 0.5–1 g applied daily for 1–2 weeks, then reduced to 2–3 times weekly for maintenance.
Contraception:
- Typically combined with progestin in oral contraceptives (e.g., 20–35 mcg ethinylestradiol daily).
Hypoestrogenism:
- 1–2 mg estradiol orally or equivalent dose transdermally.
Gender-Affirming Hormone Therapy:
- Estradiol oral: 2–6 mg daily.
- Estradiol patch: 50–200 mcg twice weekly.
4. Administration
- Oral formulations should be taken with water, at the same time each day.
- Transdermal patches should be applied to clean, dry skin (avoid breasts or waistline).
- Vaginal formulations should be applied as directed, using the applicator if provided.
5. Forms Available
- Oral tablets: Estradiol 1 mg, 2 mg; Conjugated oestrogens 0.3 mg, 0.625 mg.
- Transdermal patches: 25 mcg, 50 mcg, 100 mcg.
- Vaginal cream/ring/tablet: Estradiol or conjugated oestrogens.
- Injectable: Estradiol valerate or estradiol cypionate.
6. Side Effects
6.1 Common Side Effects:
- Nausea
- Breast tenderness
- Headache
- Bloating
- Irregular vaginal bleeding or spotting
6.2 Less Common Side Effects:
- Mood changes
- Weight gain
- Skin irritation (patches)
6.3 Rare but Serious Side Effects:
- Venous thromboembolism (VTE)
- Stroke or myocardial infarction
- Endometrial hyperplasia (if used without progestin in women with a uterus)
- Breast cancer (risk increases with prolonged use)
7. Warnings
- Thromboembolic Risk: Increased risk of deep vein thrombosis, pulmonary embolism, stroke, and myocardial infarction, especially in smokers and older women.
- Breast and Endometrial Cancer: Prolonged use of unopposed oestrogen increases the risk of endometrial cancer. Combine with progestin in women with an intact uterus.
- Hepatic Impairment: Use with caution in patients with liver disease, as oestrogens are metabolised in the liver.
8. Precautions
- Use the lowest effective dose for the shortest duration necessary to minimise risks.
- Regularly monitor for symptoms of cardiovascular disease, breast cancer, and endometrial hyperplasia.
- Avoid in patients with a history of hormone-dependent cancers, unless specifically indicated.
9. Interactions
- CYP3A4 inhibitors (e.g., ketoconazole): May increase oestrogen levels.
- CYP3A4 inducers (e.g., rifampin, phenytoin): May reduce efficacy by increasing oestrogen metabolism.
- Anticoagulants: Reduced efficacy of warfarin.
- Thyroid hormones: Oestrogen may reduce thyroid hormone efficacy; monitor thyroid function.
10. Monitoring Parameters
- Monitor for symptom improvement (e.g., reduction in hot flushes, improved bone density).
- Periodic mammograms and pelvic exams to detect cancer risks.
- Monitor blood pressure, lipid profile, and glucose levels.
11. Use in Children
- Not typically used in children unless for specific indications, such as delayed puberty or certain hormonal deficiencies.
12. Use in Pregnancy
- Contraindicated during pregnancy. Oestrogens can harm the developing foetus.
13. Use in Elderly
- Use cautiously due to an increased risk of cardiovascular events and cancer. Lower doses are recommended.
14. Use in Kidney Disease
- No specific dose adjustment is typically required, but close monitoring is advised in severe renal impairment.
15. Use in Liver Disease
- Use cautiously in patients with hepatic impairment, as metabolism may be affected.
16. Patient Counselling Points
- Take oestrogen exactly as prescribed. Do not skip doses or stop suddenly without consulting your doctor.
- Report any unusual symptoms, such as breast lumps, unexplained vaginal bleeding, or severe headaches.
- Maintain a healthy lifestyle, including a balanced diet and regular exercise, to reduce risks associated with oestrogen use.
- Attend regular follow-up appointments, including mammograms and pelvic exams.
- Avoid smoking while on oestrogen therapy, as it increases the risk of cardiovascular events.
17. Table of Brand Names, Manufacturer, and Prices in USD
Brand Name | Manufacturer | Strength/Dosage Form | Price (USD) |
---|---|---|---|
Premarin | Pfizer | 0.625 mg Tablet | $35 (30 tablets) |
Estrace | Allergan | 1 mg Tablet | $30 (30 tablets) |
Climara | Bayer | 50 mcg Patch | $50 (4 patches) |
Vagifem | Novo Nordisk | 10 mcg Vaginal Tablet | $60 (18 tablets) |
18. 15 FAQs (Frequently Asked Questions)
1. What is oestrogen used for?
Oestrogen is used for hormone replacement therapy, contraception, and certain hormone-dependent conditions.
2. How does oestrogen work?
It binds to oestrogen receptors, regulating gene expression and maintaining reproductive and other physiological functions.
3. Can oestrogen prevent menopause symptoms?
Yes, it is highly effective for managing vasomotor symptoms like hot flushes and night sweats.
4. Can oestrogen cause weight gain?
Weight gain is a potential side effect but not common in low-dose therapy.
5. Can oestrogen increase cancer risk?
Long-term use of oestrogen, especially unopposed by progestin, can increase the risk of breast and endometrial cancer.
6. Can oestrogen be used during pregnancy?
No, it is contraindicated during pregnancy.
7. What are common side effects of oestrogen?
Common side effects include nausea, breast tenderness, and bloating.
8. Is oestrogen therapy safe for elderly women?
It can be used cautiously, but risks, including cardiovascular events and cancer, must be carefully considered.
9. Can oestrogen be used alone for HRT?
Only in women who have had a hysterectomy. Otherwise, progestin must be added to prevent endometrial cancer.
10. How should oestrogen patches be applied?
Apply to clean, dry skin on the lower abdomen or buttocks. Avoid the breasts.
11. Can oestrogen affect mood?
Yes, it can influence mood, often improving depressive symptoms in menopausal women.
12. Does oestrogen protect against osteoporosis?
Yes, it helps maintain bone density and reduces the risk of fractures.
13. Can oestrogen be used for transgender women?
Yes, it is commonly used as part of gender-affirming hormone therapy.
14. How long can I take oestrogen?
It is recommended to use the lowest effective dose for the shortest duration needed.
15. Do I need regular tests while on oestrogen?
Yes, regular mammograms, pelvic exams, and blood pressure checks are essential.