OGEN

Clinical safety rating: caution

Comprehensive clinical and safety monograph for OGEN (OGEN).

How it works

Estrogen replacement therapy; binds to estrogen receptors, activating gene transcription leading to cell proliferation and differentiation in target tissues.

What the body does with it

Metabolism	Hepatic metabolism via CYP3A4 to estrone, estriol, and conjugates; enterohepatic recirculation.
Excretion	Renal elimination of conjugated metabolites (estrone sulfate, estradiol glucuronide) accounts for >95% of excretion; fecal elimination is <5%.
Half-life	Terminal elimination half-life of estrone is approximately 10-24 hours (mean ~14 hours); clinical context: permits once-daily dosing.
Protein binding	Estrone is approximately 98% bound to albumin and sex hormone-binding globulin (SHBG).
Volume of Distribution	Volume of distribution for estrone is approximately 12 L/kg, indicating extensive tissue distribution.
Bioavailability	Oral bioavailability of estrone from OGEN is approximately 5-10% due to extensive first-pass metabolism; bioavailability of conjugated estrogens (e.g., piperazine estrone sulfate) is higher, but specific to OGEN is ~5-10%.
Onset of Action	Oral: clinical effects (e.g., relief of vasomotor symptoms) typically onset within 2-4 weeks of continuous therapy.
Duration of Action	Duration of action for relief of menopausal symptoms is sustained with daily dosing; effects wane over 1-2 weeks after discontinuation.

Classification & Brands

Dosing & administration

0.75 mg orally once daily, cyclically (3 weeks on, 1 week off) for moderate to severe vasomotor symptoms associated with menopause.

Dosage form	CREAM
Renal impairment	No specific dose adjustment provided by manufacturer; use with caution in patients with severe renal impairment.
Liver impairment	Contraindicated in patients with known or suspected hepatic disease; no dose adjustment recommended due to contraindication.
Pediatric use	Not indicated for use in pediatric patients.
Geriatric use	Use lowest effective dose for shortest duration; no specific dose adjustment recommended, but monitor for estrogen-related adverse effects.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for OGEN (OGEN).

Breastfeeding

Estropipate is excreted in human milk; M/P ratio not specified. May reduce milk production and composition. Use with caution; avoid in breastfeeding mothers unless essential. Consider alternative therapies.

Teratogenic Risk

Estropipate is contraindicated in pregnancy. First trimester: associated with congenital anomalies (e.g., cardiovascular, genitourinary) based on observational studies; no adequate controlled studies. Second and third trimesters: continued exposure may increase risk of fetal genital anomalies, uterine growth restriction, and neonatal complications (e.g., jaundice, glucose intolerance). Use only if clearly needed during lactation; avoid in pregnancy.

Warnings & precautions

■ FDA Black Box Warning

Estrogens should not be used to prevent cardiovascular disease or dementia. Increased risk of endometrial cancer, stroke, deep vein thrombosis, pulmonary embolism, and myocardial infarction.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Undiagnosed abnormal genital bleeding","Known or suspected breast cancer","Known or suspected estrogen-dependent neoplasia","Active DVT, PE, or history of these conditions","Active arterial thromboembolic disease (stroke, MI)","Known protein C, protein S, or antithrombin deficiency","Known or suspected pregnancy","Hypersensitivity to estrogens or any component of the product","Hepatic impairment or disease"]

Clinical Precautions

Precautions

["Cardiovascular disorders (stroke, MI, DVT, PE)","Malignant neoplasms (endometrial cancer, breast cancer)","Gallbladder disease","Hypercalcemia","Visual abnormalities","Hepatic hemangiomas","Thyroid hormone metabolism alterations"]

Clinical Tips & Counseling

Drug interactions

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OGEN

Clinical safety rating: caution

Comprehensive clinical and safety monograph for OGEN (OGEN).

How it works

Estrogen replacement therapy; binds to estrogen receptors, activating gene transcription leading to cell proliferation and differentiation in target tissues.

What the body does with it

Metabolism	Hepatic metabolism via CYP3A4 to estrone, estriol, and conjugates; enterohepatic recirculation.
Excretion	Renal elimination of conjugated metabolites (estrone sulfate, estradiol glucuronide) accounts for >95% of excretion; fecal elimination is <5%.
Half-life	Terminal elimination half-life of estrone is approximately 10-24 hours (mean ~14 hours); clinical context: permits once-daily dosing.
Protein binding	Estrone is approximately 98% bound to albumin and sex hormone-binding globulin (SHBG).
Volume of Distribution	Volume of distribution for estrone is approximately 12 L/kg, indicating extensive tissue distribution.
Bioavailability	Oral bioavailability of estrone from OGEN is approximately 5-10% due to extensive first-pass metabolism; bioavailability of conjugated estrogens (e.g., piperazine estrone sulfate) is higher, but specific to OGEN is ~5-10%.
Onset of Action	Oral: clinical effects (e.g., relief of vasomotor symptoms) typically onset within 2-4 weeks of continuous therapy.
Duration of Action	Duration of action for relief of menopausal symptoms is sustained with daily dosing; effects wane over 1-2 weeks after discontinuation.

Classification & Brands

Dosing & administration

0.75 mg orally once daily, cyclically (3 weeks on, 1 week off) for moderate to severe vasomotor symptoms associated with menopause.

Dosage form	CREAM
Renal impairment	No specific dose adjustment provided by manufacturer; use with caution in patients with severe renal impairment.
Liver impairment	Contraindicated in patients with known or suspected hepatic disease; no dose adjustment recommended due to contraindication.
Pediatric use	Not indicated for use in pediatric patients.
Geriatric use	Use lowest effective dose for shortest duration; no specific dose adjustment recommended, but monitor for estrogen-related adverse effects.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for OGEN (OGEN).

Breastfeeding

Teratogenic Risk

Warnings & precautions

■ FDA Black Box Warning

Estrogens should not be used to prevent cardiovascular disease or dementia. Increased risk of endometrial cancer, stroke, deep vein thrombosis, pulmonary embolism, and myocardial infarction.