Indications
Therapeutic Class
Pharmacology
Endogenous estrogens are largely responsible for the development and maintenance of the female reproductive system and secondary sexual characteristics. Although circulating estrogens exist in a dynamic equilibrium of metabolic interconversions, estradiol is the principal intracellular human estrogen and is substantially more potent than its metabolites, estrone and estriol, at the receptor level.
The primary source of estrogen in normally cycling adult women is the ovarian follicle, which secretes 70 to 500 mcg of estradiol daily, depending on the phase of the menstrual cycle. After menopause, most endogenous estrogen is produced by conversion of androstenedione, which is secreted by the adrenal cortex, to estrone in the peripheral tissues. Thus, estrone and the sulfate-conjugated form, estrone sulfate, are the most abundant circulating estrogen in postmenopausal women.
Estrogens act through binding to nuclear receptors in estrogen-responsive tissues. To date, two estrogen receptors have been identified. These vary in proportion from tissue to tissue. Circulating estrogens modulate the pituitary secretion of the gonadotropins, luteinizing hormone (LH) and follicle stimulating hormone (FSH), through a negative feedback mechanism. Estrogens act to reduce the elevated levels of these gonadotropins seen in postmenopausal women.
Dosage & Administration
Menopausal vasomotor symptoms: 0.45 mg/day, up to 1.25 mg/day. Attempt to discontinue medication at 3-6-mth intervals.
Vulvular and vaginal atrophy: 0.3 mg/day.
Female hypogonadism: 0.3-0.625 mg/day in a cyclical regimen. Add progestin treatment once skeletal maturity is achieved.
Female castration, Primary ovarian failure: 1.25 mg/day in a cyclical regimen. Palliation in prostate carcinoma 1.25-2.5 mg 3 times/day.
Osteoporosis prophylaxis in postmenopausal women: Initial: 0.3 mg/day in a cyclical or continuous regimen depending on patient’s condition.
Interaction
The metabolism of estrogens may be increased by concomitant use of substances known to induce drug-metabolising enzymes, specifically cytochrome P450 enzymes, such as anticonvulsants (e.g. phenobarbital, phenytoin, carbamazepine) and anti-infectives (e.g. rifampicin, rifabutin, nevirapine, efavirenz).
Ritonavir and nelfinavir, although known as strong inhibitors, by contrast exhibit inducing properties when used concomitantly with steroid hormones.
Contraindications
Side Effects
Pregnancy & Lactation
For women with a uterus: If pregnancy occurs during medication with Conjugated Oestrogens treatment should be withdrawn immediately. The results of most epidemiological studies to date relevant to inadvertent foetal exposure to estrogens indicate no teratogenic or foetotoxic effects.
Lactation: Conjugated Oestrogens is not indicated during lactation.
Reviews
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