Estradiol: Drug Information
1. Drug Name
Generic Name
Estradiol
Brand Name(s)
- Pakistan: Estranon
- India: Progynova, Estragyn
- US: Estrace, Climara, Vivelle-Dot
- UK: Estraderm, Estrogel
2. Pharmacological Class
Class
Estrogen
Subclass
Steroidal estrogen
3. Mechanism of Action
Estradiol is a natural estrogen hormone and acts by binding to and activating the estrogen receptors (ERα and ERβ). This leads to the modulation of various physiological processes in the body.
4. Indications
Primary Indications
- Menopausal symptoms: Treatment of hot flashes, vaginal dryness, and other symptoms of menopause.
- Postmenopausal osteoporosis: Prevention of osteoporosis in postmenopausal women.
- Estrogen deficiency: Replacement therapy in women with ovarian failure or other conditions that cause estrogen deficiency.
Off-label Uses
- Contraception: Estradiol is sometimes used in combination with progestins for contraception.
- Hormone replacement therapy (HRT) in transgender women
5. Dosage and Administration
Standard Dosage
For oral tablets (Estrace):
- Menopausal symptoms: 0.5-2 mg daily, adjusted based on response and severity of symptoms.
- Postmenopausal osteoporosis: 1-2 mg daily, depending on risk factors.
For transdermal patches (Climara, Vivelle-Dot):
- Menopausal symptoms: 0.025-0.1 mg/day applied to the skin twice weekly.
Route of Administration
Oral (tablets), Transdermal (patches), Intravaginal (cream, ring)
Special Populations
- Pediatric: Not indicated for use in children.
- Geriatric: Use with caution in elderly patients, adjust dosage based on individual response and risk factors.
6. Pharmacokinetics
Absorption
Well-absorbed after oral administration.
Distribution
Widely distributed throughout the body, including the CNS. Protein binding is high (about 98%).
Metabolism
Metabolized in the liver, primarily by cytochrome P450 enzymes.
Excretion
Excreted in the urine, primarily as conjugated metabolites.
Half-life
Elimination half-life is approximately 13-20 hours.
7. Contraindications
- Known or suspected breast cancer or estrogen-dependent tumors
- Undiagnosed abnormal genital bleeding
- Active thrombophlebitis or thromboembolic disorders
- Severe liver dysfunction
8. Warnings and Precautions
- Increased risk of endometrial cancer
- Increased risk of cardiovascular events, including stroke and deep vein thrombosis
- Monitor for signs of estrogen-related adverse effects
9. Side Effects
Common Side Effects
- Headache
- Breast tenderness
- Nausea
Serious Side Effects
- Endometrial hyperplasia or cancer
- Cardiovascular events
- Cholestatic jaundice
10. Drug Interactions
Major Interactions
- Warfarin
- Rifampin
Moderate Interactions
- Phenytoin
- St. John's Wort
Minor Interactions
- Ascorbic acid (Vitamin C)
- Acetaminophen
11. Pregnancy and Lactation
Pregnancy Category
Category X - Contraindicated during pregnancy.
Breastfeeding Considerations
Not recommended during breastfeeding. Small amounts of estradiol may pass into breast milk.
12. Patient Counseling Information
- Take as directed and do not exceed prescribed dose.
- Report any unusual vaginal bleeding or symptoms immediately.
- Discuss contraceptive options and potential side effects with your healthcare provider.