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Premarin (Estrogens, Conjugated)
Conjugated estrogens bind to nuclear estrogen receptors in estrogen-responsive tissues, modulating gonadotropin secretion and reducing elevated LH and FSH levels in postmenopausal women.
PREMARIN is a conjugated estrogen mixture indicated for vasomotor symptoms, vulvar/vaginal atrophy, hypoestrogenism, metastatic breast cancer palliation, prostate cancer palliation, and osteoporosis prevention. The drug is contraindicated in undiagnosed abnormal bleeding, active or prior thromboembolic disease, breast cancer, hepatic impairment, and thrombophilic disorders. CYP3A4 inducers may reduce efficacy while inhibitors may increase side effects. PREMARIN remains a standard hormone replacement therapy option when appropriate patient selection and risk-benefit assessment are performed.
At a glance
| Generic name | Estrogens, Conjugated |
|---|---|
| Sponsor | Pfizer |
| Drug class | Estrogen replacement therapy |
| Target | Estrogen receptors (nuclear receptors) |
| Phase | FDA-approved |
| First approval | 1942 |
Mechanism of action
Endogenous estrogens are responsible for development and maintenance of the female reproductive system and secondary sexual characteristics. Estradiol is the principal intracellular human estrogen and substantially more potent than its metabolites estrone and estriol at the receptor level. Exogenous conjugated estrogens act through binding to nuclear estrogen receptors in estrogen-responsive tissues, with two estrogen receptors identified that vary in proportion by tissue. Circulating estrogens modulate pituitary secretion of gonadotropins (LH and FSH) through negative feedback mechanism, acting to reduce the elevated levels of these gonadotropins seen in postmenopausal women.
Approved indications
- Dyspareunia
- Menopausal flushing
Common side effects
- Headache
- Nasopharyngitis
- Upper respiratory tract infection
- Nausea
- Diarrhoea
Drug interactions
- CYP3A4 inducers (St. John's Wort, phenobarbital, carbamazepine, rifampin)
- CYP3A4 inhibitors (erythromycin, clarithromycin, ketoconazole, itraconazole, ritonavir, grapefruit juice)
- Medroxyprogesterone acetate (MPA)
Primary sources
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| Source | Used for |
|---|---|
| FDA label | Mechanism, indications, dosing, boxed warnings, drug interactions |