Conjugated estrogens (injection)

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# Black Box Warning

# Overview
Conjugated estrogens (injection) is a hormone that is FDA approved for the treatment of abnormal uterine bleeding due to hormonal imbalance in the absence of organic pathology. There is a Black Box Warning for this drug as shown here.  Common adverse reactions include edema, vasodilatation, chloasma, hirsutism, injection site reaction, pruritus, weight change, abdominal pain, bloating, diarrhea, flatulence, nausea, vomiting, backache, leg cramp, asthenia, headache, migraine, depression, disturbance in mood, disorder of menstruation, pain of breast, vaginitis, withdrawal bleeding, cough, and pharyngitis.

# Adult Indications and Dosage

## FDA-Labeled Indications and Dosage (Adult)

### Abnormal Uterine Bleeding
Premarin Intravenous (conjugated estrogens, USP) for injection is indicated in the treatment of abnormal uterine bleeding due to hormonal imbalance in the absence of organic pathology. Premarin Intravenous is indicated for short-term use only, to provide a rapid and temporary increase in estrogen levels.
- For treatment of abnormal uterine bleeding due to hormonal imbalance in the absence of organic pathology:
- One 25 mg injection, intravenously or intramuscularly.
- Intravenous use is preferred since more rapid response can be expected from this mode of administration. Repeat in 6 to 12 hours if necessary. The use of Premarin Intravenous for injection does not preclude the advisability of other appropriate measures.
- One should adhere to the usual precautionary measures governing intravenous administration. Injection should be made slowly to obviate the occurrence of flushes.
- Infusion of Premarin Intravenous for injection with other agents is not generally recommended. In emergencies, however, when an infusion has already been started it may be expedient to make the injection into the tubing just distal to the infusion needle. If so used, compatibility of solutions must be considered.

## Off-Label Use and Dosage (Adult)

### Guideline-Supported Use
There is limited information regarding Off-Label Guideline-Supported Use of Conjugated estrogens in adult patients.

### NonGuideline-Supported Use

### Bleeding, Renal Failure
- Dosing Information
- 1050 mg IV/IM per day

### Gender Identity Disorder
- Dosing Information
- 10 mg IV/IM

### Hemorrhagic Cystitis
- Dosing Information
- 550 mg IV

### Postcoital Contraception
- Dosing Information
- A single 50 mg intravenous (IV) dose, followed by a second 50 mg IV dose 24 hours later.

### Postoperative Hemorrhage
- Dosing Information
- 1 mg/kg IV

### Turner Syndrome
- Dosing Information
- 0.375 mg/kg IV

# Pediatric Indications and Dosage

## FDA-Labeled Indications and Dosage (Pediatric)
Safety and effectiveness in the pediatric population below the age of 12 years have not been established.

## Off-Label Use and Dosage (Pediatric)

### Guideline-Supported Use
There is limited information regarding Off-Label Guideline-Supported Use of Conjugated estrogens in pediatric patients.

### NonGuideline-Supported Use
There is limited information regarding Off-Label NonGuideline-Supported Use of Conjugated estrogens in pediatric patients.

# Contraindications
Premarin Intravenous therapy should not be used in individuals with any of the following conditions:
- Undiagnosed abnormal genital bleeding.
- Known, suspected, or history of breast cancer.
- Known or suspected estrogen-dependent neoplasia.
- Active DVT, PE or a history of these conditions.
- Active arterial thromboembolic disease (for example, stroke and MI) or a history of these conditions.
- Known anaphylactic reaction and angioedema to Premarin Intravenous therapy.
- Known liver dysfunction or disease.
- Known protein C, protein S, or antithrombin deficiency or other known thrombophilic disorders.
- Known or suspected pregnancy.

# Warnings
Premarin Intravenous for injection is indicated for short-term use. However, warnings, precautions and adverse reactions associated with oral Premarin treatment should be taken into account.

### Cardiovascular Disorders
- An increased risk of stroke and DVT has been reported with estrogen-alone therapy.
- An increased risk of PE, DVT, stroke, and MI has been reported with estrogen plus progestin therapy.
- Should any of these events occur or be suspected, estrogen with or without progestin therapy should be discontinued immediately.
- Risk factors for arterial vascular disease (for example, hypertension, diabetes mellitus, tobacco use, hypercholesterolemia, and obesity) and/or venous thromboembolism (VTE) (for example, personal history or family history of VTE, obesity, and systemic lupus erythematosus) should be managed appropriately.
- In the WHI estrogen-alone sub study, a statistically significant increased risk of stroke was reported in women 50 to 79 years of age receiving daily CE (0.625 mg)-alone compared to women in the same age group receiving placebo (45 versus 33 per 10,000 women-years). The increase in risk was demonstrated in year 1 and persisted. Should a stroke occur or be suspected, estrogen-alone therapy should be discontinued immediately.
- Subgroup analyses of women 50 to 59 years of age suggest no increased risk of stroke for those women receiving CE (0.625 mg)-alone versus those receiving placebo (18 versus 21 per 10,000 women-years).
- In the WHI estrogen plus progestin substudy, a statistically significant increased risk of stroke was reported in women 50 to 79 years of age receiving daily CE (0.625 mg) plus MPA (2.5 mg) compared to women in the same age group receiving placebo (33 versus 25 per 10,000 women-years).  The increase in risk was demonstrated after the first year and persisted. Should a stroke occur or be suspected, estrogen plus progestin therapy should be discontinued immediately.
- In the WHI estrogen-alone substudy, no overall effect on CHD events (defined as nonfatal MI, silent MI, or CHD death) was reported in women receiving estrogen-alone compared to placebo.
- In the WHI estrogen plus progestin substudy, there was a non-statistically significant increased risk of CHD events reported in women receiving daily CE (0.625 mg) plus MPA (2.5 mg) compared to women receiving placebo (41 versus 34 per 10,000 women-years). An increase in relative risk was demonstrated in year 1, and a trend toward decreasing relative risk was reported in years 2 through 5.
- In postmenopausal women with documented heart disease (n = 2,763, average 66.7 years of age), in a controlled clinical glual of secondary prevention of cardiovascular disease (Heart and Estrogen/Progestin Replacement Study; HERS), treatment with daily CE 0.625 mg/MPA 2.5 mg demonstrated no cardiovascular benefit. During an average follow-up of 4.1 years, treatment with CE plus MPA did not reduce the overall rate of CHD events in postmenopausal women with established coronary heart disease. There were more CHD events in the CE plus MPA-treated group than in the placebo group in year one, but not during the subsequent years. Two thousand three hundred and twenty-one (2,321) women from the original HERS trial agreed to participate in an open-label extension of HERS, HERS II. Average follow-up in HERS II was an additional 2.7 years, for a total of 6.8 years overall. Rates of CHD events were comparable among women in the CE plus MPA group and the placebo group in the HERS, the HERS II, and overall.
- In the WHI estrogen-alone substudy, the risk of VTE (DVT and PE), was increased for women receiving daily CE (0.625 mg)-alone compared to placebo (30 versus 22 per 10,000 women-years), although only the increased risk of DVT reached statistical significance (23 versus 15 per 10,000 women-years). The increase in VTE risk was demonstrated during the first 2 years. Should a VTE occur or be suspected, estrogen-alone therapy should be discontinued immediately.
- In the WHI estrogen plus progestin substudy, a statistically significant 2-fold greater rate of VTE was reported in women receiving daily CE (0.625 mg) plus MPA (2.5 mg) compared to women receiving placebo (35 versus 17 per 10,000 women-years). Statistically significant increases in risk for both DVT (26 versus 13 per 10,000 women-years) and PE (18 versus 8 per 10,000 women-years) were also demonstrated. The increase in VTE risk was demonstrated during the first year and persisted. Should a VTE occur or be suspected, estrogen plus progestin therapy should be discontinued immediately.

### Malignant Neoplasms
- An increased risk of endometrial cancer has been reported with the use of unopposed estrogen therapy in women with a uterus. The reported endometrial cancer risk among unopposed estrogen users is about 2 to 12 times greater than in non-users, and appears dependent on duration of treatment and on estrogen dose. Most studies show no significant increased risk associated with use of estrogen for less than 1 year. The greatest risk appears associated with prolonged use, with increased risks of 15- to 24-fold for 5 to 10 years or more and this risk has been shown to persist for at least 8 to 15 years after estrogen therapy is discontinued.
- The most important randomized clinical trial providing information about breast cancer in estrogen-alone users is the WHI substudy of daily CE (0.625 mg)-alone. In the WHI estrogen-alone substudy, after an average follow-up of 7.1 years, daily CE (0.625 mg)-alone was not associated with an increased risk of invasive breast cancer (relative risk  0.80).
- The most important randomized clinical trial providing information about breast cancer in estrogen plus progestin users is the WHI substudy of daily CE (0.625 mg) plus MPA (2.5 mg). After a mean follow-up of 5.6 years, the estrogen plus progestin substudy reported an increased risk of invasive breast cancer in women who took daily CE plus MPA. In this substudy, prior use of estrogen-alone or estrogen plus progestin therapy was reported by 26 percent of the women. The relative risk of invasive breast cancer was 1.24, and the absolute risk was 41 versus 33 cases per 10,000 women-years, for CE plus MPA compared with placebo, respectively. Among women who reported prior use of hormone therapy, the relative risk of invasive breast cancer was 1.86, and the absolute risk was 46 versus 25 cases per 10,000 women-years, for CE plus MPA compared with placebo. Among women who reported no prior use of hormone therapy, the relative risk of invasive breast cancer was 1.09, and the absolute risk was 40 versus 36 cases per 10,000 women-years for CE plus MPA compared with placebo. In the same substudy, invasive breast cancers were larger, were more likely to be node positive, and were diagnosed at a more advanced stage in the CE (0.625 mg) plus MPA (2.5 mg) group compared with the placebo group. Metastatic disease was rare, with no apparent difference between the two groups. Other prognostic factors, such as histologic subtype, grade and hormone receptor status did not differ between the groups.
- Consistent with the WHI clinical trial, observational studies have also reported an increased risk of breast cancer for estrogen plus progestin therapy, and a smaller increased risk for estrogen-alone therapy, after several years of use. The risk increased with duration of use, and appeared to return to baseline over about 5 years after stopping treatment (only the observational studies have substantial data on risk after stopping). Observational studies also suggest that the risk of breast cancer was greater, and became apparent earlier, with estrogen plus progestin therapy as compared to estrogen-alone therapy. However, these studies have not found significant variation in the risk of breast cancer among different estrogen plus progestin combinations, doses, or routes of administration.
- The use of estrogen-alone and estrogen plus progestin has been reported to result in an increase in abnormal mammograms requiring further evaluation.
- All women should receive yearly breast examinations by a healthcare provider and perform monthly breast self-examinations. In addition, mammography examinations should be scheduled based on patient age, risk factors, and prior mammogram results.
- The WHI estrogen plus progestin substudy reported a statistically non-significant increased risk of ovarian cancer. After an average follow-up of 5.6 years, the relative risk for ovarian cancer for CE plus MPA versus placebo was 1.58 (95 percent CI, 0.77  3.24). The absolute risk for CE plus MPA versus placebo was 4 versus 3 cases per 10,000 women-years. In some epidemiologic studies, the use of estrogen plus progestin and estrogen-only products, in particular for 5 or more years, has been associated with an increased risk of ovarian cancer. However, the duration of exposure associated with increased risk is not consistent across all epidemiologic studies and some report no association.

### Probable Dementia
- In the WHIMS estrogen-alone ancillary study of WHI, a population of 2,947 hysterectomized women 65 to 79 years of age was randomized to daily CE (0.625 mg)-alone or placebo.
- After an average follow-up of 5.2 years, 28 women in the estrogen-alone group and 19 women in the placebo group were diagnosed with probable dementia. The relative risk of probable dementia for CE-alone versus placebo was 1.49 (95 percent CI, 0.832.66). The absolute risk of probable dementia for CE-alone versus placebo was 37 versus 25 cases per 10,000 women-years.
- In the WHIMS estrogen plus progestin ancillary study of WHI, a population of 4,532 postmenopausal women 65 to 79 years of age was randomized to daily CE (0.625 mg) plus MPA (2.5 mg) or placebo.
- After an average follow-up of 4 years, 40 women in the CE plus MPA group and 21 women in the placebo group were diagnosed with probable dementia. The relative risk of probable dementia for CE plus MPA versus placebo was 2.05 (95 percent CI 1.213.48). The absolute risk of probable dementia for CE plus MPA versus placebo was 45 versus 22 cases per 10,000 women-years.
- When data from the two populations in the WHIMS estrogen-alone and estrogen plus progestin ancillary studies were pooled as planned in the WHIMS protocol, the reported overall relative risk for probable dementia was 1.76 (95 percent CI, 1.192.60). Since both substudies were conducted in women 65 to 79 years of age, it is unknown whether these findings apply to younger postmenopausal women.

### Gallbladder Disease
- A 2- to 4-fold increase in the risk of gallbladder disease requiring surgery in postmenopausal women receiving postmenopausal estrogens has been reported.

### Hypercalcemia
- Estrogen administration may lead to severe hypercalcemia in patients with breast cancer and bone metastases. If hypercalcemia occurs, use of the drug should be stopped and appropriate measures taken to reduce the serum calcium level.

### Visual Abnormalities
- Retinal vascular thrombosis has been reported in patients receiving estrogen. Discontinue medication pending examination if there is sudden partial or complete loss of vision, or a sudden onset of proptosis, diplopia, or migraine. If examination reveals papilledema or retinal vascular lesions, estrogen should be permanently discontinued.

### Anaphylactic Reaction and Angioedema
- Cases of anaphylaxis, which developed within minutes to hours after using PREMARIN Intravenous and require emergency medical management, have been reported in the postmarketing setting. Skin (hives, pruritis, swollen lips-tongue-face) and either respiratory tract (respiratory compromise) or gastrointestinal tract (abdominal pain, vomiting) involvement has been noted.
- Angioedema involving the tongue, larynx, face, hands, and feet requiring medical intervention has occurred postmarketing in patients using PREMARIN Intravenous. If angioedema involves the tongue, glottis, or larynx, airway obstruction may occur. Patients who develop an anaphylactic reaction with or without angioedema after treatment with PREMARIN Intravenous should not receive PREMARIN Intravenous again.

### Hereditary Angioedema
- Exogenous estrogens may induce or exacerbate symptoms of angioedem, particularly in women with hereditary angioedema.

## Precautions

### General
- Premarin Intravenous for injection is indicated for short-term use. However, warnings, precautions and adverse reactions associated with oral Premarin treatment should be taken into account.
- Studies of the addition of a progestin for 10 or more days of a cycle of estrogen administration or daily with estrogen in a continuous regimen have reported a lowered incidence of endometrial hyperplasia than would be induced by estrogen treatment alone. Endometrial hyperplasia may be a precursor to endometrial cancer.
- There are, however, possible risks which may be associated with the use of progestins with estrogen compared to estrogen-alone regimens. These include an increased risk of breast cancer.
- In a small number of case reports, substantial increases in blood pressure have been attributed to idiosyncratic reactions to estrogens. In a large, randomized, placebo-controlled clinical trial, a generalized effect of estrogen therapy on blood pressure was not seen.
- In women with pre-existing hypertriglyceridemia, estrogen therapy may be associated with elevations of plasma triglycerides leading to pancreatitis. Consider discontinuation of treatment if pancreatitis occurs.
- Estrogen may be poorly metabolized in women with impaired liver function. For women with a history of cholestatic jaundice associated with past estrogen use or with pregnancy, caution should be exercised, and in the case of recurrence, medication should be discontinued.
- Estrogen administration leads to increased thyroid-binding globulin (TBG) levels. Women with normal thyroid function can compensate for the increased TBG by making more thyroid hormone, thus maintaining free T4 and T3 serum concentrations in the normal range. Women dependent on thyroid hormone replacement therapy who are also receiving estrogen may require increased doses of their thyroid replacement therapy. These women should have their thyroid function monitored in order to maintain their free thyroid hormone levels in an acceptable range.
- Estrogens may cause some degree of fluid retention. Women with conditions that might be influenced by this factor, such as a cardiac or renal dysfunction, warrant careful observation when estrogen are prescribed.
- Estrogen therapy should be used with caution in individuals with hypoparathyroidism as estrogen-induced hypocalcemia may occur.
- A few cases of malignant transformation of residual endometrial implants have been reported in women treated post-hysterectomy with estrogen-alone therapy. For women known to have residual endometriosis post-hysterectomy, the addition of progestin should be considered.
- Estrogen therapy may cause an exacerbation of asthma, diabetes mellitus, epilepsy, migraine, porphyria, systemic lupus erythematosus, and hepatic hemangiomas and should be used with caution in women with these conditions.

# Adverse Reactions

## Clinical Trials Experience
There is limited information regarding Conjugated estrogens (injection) Clinical Trials Experience in the drug label.

## Postmarketing Experience
Premarin Intravenous for injection is indicated for short-term use. However, the warnings, precautions and adverse reactions associated with oral Premarin treatment should be taken into account.
The following adverse reactions have been identified during post-approval use of oral or intravenous Premarin. Because these reactions are reported voluntarily from a population of uncertain size, it is not possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

### Genitourinary System
- Abnormal uterine bleeding/spotting.
- Dysmenorrhea or pelvic pain.
- Increase in size of uterine leiomyomata.
- Vaginitis, including vaginal candidiasis.
- Change in amount of cervical secretion.
- Change in cervical ectropion.
- Ovarian cancer.
- Endometrial hyperplasia.
- Endometrial cancer.

### Breasts
- Tenderness, enlargement, pain, discharge, galactorrhea.
- Fibrocystic breast changes.
- Breast cancer.

### Cardiovascular System
- Deep and superficial venous thrombosis.
- Pulmonary embolism.
- Thrombophlebitis.
- Myocardial infarction.
- Stroke.
- Increase in blood pressure.

### Gastrointestinal System
- Nausea, vomiting.
- Abdominal cramps, bloating.
- Cholestatic jaundice.
- Increased incidence of gallbladder disease.
- Pancreatitis.
- Enlargement of hepatic hemangiomas.
- Ischemic colitis.

### Skin
- Chloasma or melasma that may persist when drug is discontinued.
- Erythema multiforme.
- Erythema nodosum.
- Hemorrhagic eruption.
- Loss of scalp hair.
- Hirsutism.
- Pruritis.
- Rash.

### Eyes
- Retinal vascular thrombosis.
- Intolerance to contact lenses.

### Central Nervous System
- Headache.
- Migraine.
- Dizziness.
- Mental depression.
- Exacerbation of chorea.
- Nervousness.
- Exacerbation of epilepsy.
- Dementia.
- Possible growth potentiation of benign meningioma.

### Miscellaneous
- Increase or decrease in weight.
- Glucose intolerance.
- Aggravation of porphyria.
- Edema.
- Arthralgia.
- Leg cramps.
- Changes in libido.
- Urticaria.
- Hypocalcemia (preexisting condition).
- Injection site pain.
- Injection site edema.
- Phlebitis (injection site).
- Exacerbation of asthma.
- Increased triglycerides.

# Drug Interactions
- Data from a single-dose drug-drug interaction study involving oral CE and MPA indicate that the pharmacokinetic dispositions of both drugs are not altered when the drugs are coadministered. No other clinical drug-drug interaction studies have been conducted with conjugated estrogens.
- In vitro and in vivo studies have shown that estrogens are metabolized partially by cytochrome P450 3A4 (CYP3A4). Therefore, inducers or inhibitors of CYP3A4 may affect estrogen drug metabolism. Inducers of CYP3A4, such as St. John's wort (Hypericum perforatum) preparations, phenobarbital, carbamazepine, and rifampin, may reduce plasma concentrations of estrogens, possibly resulting in a decrease in therapeutic effects and/or changes in the uterine bleeding profile. Inhibitors of CYP3A4, such as erythromycin, clarithromycin, ketoconazole, itraconazole, ritonavir and grapefruit juice, may increase plasma concentrations of estrogens and may result in side effects.

# Use in Specific Populations

### Pregnancy
Pregnancy Category (FDA): X
Premarin Intravenous should not be used during pregnancy.
Pregnancy Category (AUS): D
There is no Australian Drug Evaluation Committee (ADEC) guidance on usage of Conjugated estrogens (injection) in women who are pregnant.

### Labor and Delivery
There is no FDA guidance on use of Conjugated estrogens (injection) during labor and delivery.

### Nursing Mothers
- Premarin Intravenous should not be used during lactation. Estrogen administration to nursing women has been shown to decrease the quantity and quality of the breast milk. Detectable amounts of estrogens have been identified in the breast milk of women receiving estrogens. Caution should be exercised when Premarin Intravenous is administered to a nursing woman.

### Pediatric Use
- Estrogen therapy has been used for the induction of puberty in adolescents with some forms of pubertal delay. Safety and effectiveness in pediatric patients have not otherwise been established.
- Large and repeated doses of estrogen over an extended time period have been shown to accelerate epiphyseal closure, which could result in short adult stature if treatment is initiated before the completion of physiologic puberty in normally developing children. If estrogen is administered to patients whose bone growth is not complete, periodic monitoring of bone maturation and effects on epiphyseal centers is recommended during estrogen administration.
- Estrogen treatment of prepubertal girls also induces premature breast development and vaginal cornification, and may induce vaginal bleeding. In boys, estrogen treatment may modify the normal pubertal process and induce gynecomastia.

### Geriatic Use
- There have not been sufficient numbers of geriatric patients involved in studies utilizing Premarin to determine whether those over 65 years of age differ from younger subjects in their response to Premarin.

### Gender
There is no FDA guidance on the use of Conjugated estrogens (injection) with respect to specific gender populations.

### Race
There is no FDA guidance on the use of Conjugated estrogens (injection) with respect to specific racial populations.

### Renal Impairment
There is no FDA guidance on the use of Conjugated estrogens (injection) in patients with renal impairment.

### Hepatic Impairment
There is no FDA guidance on the use of Conjugated estrogens (injection) in patients with hepatic impairment.

### Females of Reproductive Potential and Males
There is no FDA guidance on the use of Conjugated estrogens (injection) in women of reproductive potentials and males.

### Immunocompromised Patients
There is no FDA guidance one the use of Conjugated estrogens (injection) in patients who are immunocompromised.

# Administration and Monitoring

### Administration
- Intravenous
- Intramuscular

### Monitoring
- Women dependent on thyroid hormone replacement therapy who are also receiving estrogens may require increased doses of their thyroid replacement therapy. These women should have their thyroid function monitored in order to maintain their free thyroid hormone levels in an acceptable range.
- Estrogen administration should be guided by clinical response at the lowest dose, rather than laboratory monitoring.
- If estrogen is administered to patients whose bone growth is not complete, periodic monitoring of bone maturation and effects on epiphyseal centers is recommended during estrogen administration.

# IV Compatibility
There is limited information regarding the compatibility of Conjugated estrogens (injection) and IV administrations.

# Overdosage
- Overdosage of estrogen may cause nausea, vomiting, breast tenderness, abdominal pain, drowsiness and fatigue, and withdrawal bleeding may occur in women. Treatment of overdose consists of discontinuation of Premarin therapy with institution of appropriate symptomatic care.

# Pharmacology

## Mechanism of Action
- 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, 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.

## Structure
There is limited information regarding Structure of Conjugated Estrogens in the drug label.

## Pharmacodynamics
There is limited information regarding Pharmacodynamics of Conjugated Estrogens in the drug label.

## Pharmacokinetics
- Conjugated estrogens are water-soluble and are well-absorbed through the skin, mucous membranes, and gastrointestinal tract after release from the drug formulation.
- The distribution of exogenous estrogens is similar to that of endogenous estrogens. Estrogens are widely distributed in the body and are generally found in higher concentration in the sex hormone target organs. Estrogens circulate in the blood largely bound to sex hormone-binding globulin (SHBG) and albumin.
- Exogenous estrogens are metabolized in the same manner as endogenous estrogens. Circulating estrogens exist in a dynamic equilibrium of metabolic interconversions. These transformations take place mainly in the liver. Estradiol is converted reversibly to estrone, and both can be converted to estriol, which is a major urinary metabolite. Estrogens also undergo enterohepatic recirculation via sulfate and glucuronide conjugation in the liver, biliary secretion of conjugates into the intestine, and hydrolysis in the intestine followed by reabsorption. In postmenopausal women a significant proportion of the circulating estrogens exist as sulfate conjugates, especially estrone sulfate, which serves as a circulating reservoir for the formation of more active estrogens.
- Estradiol, estrone, and estriol are excreted in the urine along with glucuronide and sulfate conjugates.
- No pharmacokinetic studies were conducted in special populations, including patients with renal or hepatic impairment.
- Data from a single-dose drug-drug interaction study involving oral CE and MPA indicate that the pharmacokinetic dispositions of both drugs are not altered when the drugs are coadministered. No other clinical drug-drug interaction studies have been conducted with conjugated estrogens.
- In vitro and in vivo studies have shown that estrogens are metabolized partially by cytochrome P450 3A4 (CYP3A4). Therefore, inducers or inhibitors of CYP3A4 may affect estrogen drug metabolism. Inducers of CYP3A4, such as St. John's wort (Hypericum perforatum) preparations, phenobarbital, carbamazepine, and rifampin, may reduce plasma concentrations of estrogens, possibly resulting in a decrease in therapeutic effects and/or changes in the uterine bleeding profile. Inhibitors of CYP3A4, such as erythromycin, clarithromycin, ketoconazole, itraconazole, ritonavir and grapefruit juice, may increase plasma concentrations of estrogens and may result in side effects.

## Nonclinical Toxicology
There is limited information regarding Nonclinical Toxicology of Conjugated Estrogens in the drug label.

# Clinical Studies

### Women's Health Initiative Studies
- The Women's Health Initiative (WHI) enrolled approximately 27,000 predominantly healthy postmenopausal women in two substudies to assess the risks and benefits of daily oral CE (0.625 mg)-alone or in combination with MPA (2.5 mg) compared to placebo in the prevention of certain chronic diseases. The primary endpoint was the incidence of coronary heart disease , with invasive breast cancer as the primary adverse outcome. A "global index" included the earliest occurrence of CHD, invasive breast cancer, stroke, PE, endometrial cancer (only in CE plus MPA substudy), colorectal cancer, hip fracture, or death due to other causes. These studies did not evaluate the effects of CE-alone or CE plus MPA on menopausal symptoms.

### WHI Estrogen-Alone Substudy
- The WHI estrogen-alone substudy was stopped early because an increased risk of stroke was observed, and it was deemed that no further information would be obtained regarding the risks and benefits of estrogen-alone in predetermined primary endpoints.
- Results of the estrogen-alone substudy, which included 10,739 women (average 63 years of age, range 50 to 79; 75.3 percent White, 15.1 percent Black, 6.1 percent Hispanic, 3.6 percent Other) after an average follow-up of 7.1 years, are presented in Table 1.
- For those outcomes included in the WHI "global index" that reached statistical significance, the absolute excess risk per 10,000 women-years in the group treated with CE-alone were 12 more strokes, while the absolute risk reduction per 10,000 women-years was 7 fewer hip fractures. The absolute excess risk of events included in the "global index" was a nonsignificant 5 events per 10,000 women-years. There was no difference between the groups in terms of all-cause mortality.
- No overall difference for primary CHD events (nonfatal MI, silent MI and CHD death) and invasive breast cancer incidence in women receiving CE-alone compared with placebo was reported in final centrally adjudicated results from the estrogen-alone substudy, after an average follow-up of 7.1 years.
- Centrally adjudicated results for stroke events from the estrogen-alone substudy, after an average follow-up of 7.1 years, reported no significant difference in distribution of stroke subtype or severity, including fatal strokes, in women receiving CE-alone compared to placebo. Estrogen alone increased the risk of ischemic stroke, and this excess was present in all subgroups of women examined.
- Timing of the initiation of estrogen-alone therapy relative to the start of menopause may affect the overall risk benefit profile. The WHI estrogen-alone substudy stratified by age showed in women 50 to 59 years of age, a non-significant trend toward reduced risk for CHD  and overall mortality .

### WHI Estrogen Plus Progestin Substudy
- The WHI estrogen plus progestin substudy was stopped early. According to the predefined stopping rule, after an average follow-up of 5.6 years of treatment, the increased risk of invasive breast cancer and cardiovascular events exceeded the specified benefits included in the "global index." The absolute excess risk of events included in the "global index" was 19 per 10,000 women-years.
- For those outcomes included in the WHI "global index" that reached statistical significance after 5.6 years of follow-up, the absolute excess risks per 10,000 women years in the group treated with CE plus MPA were 7 more CHD events, 8 more strokes, 10 more PEs, and 8 more invasive breast cancers, while the absolute risk reductions per 10,000 women-years were 6 fewer colorectal cancers and 5 fewer hip fractures. Results of the estrogen plus progestin substudy, which included 16,608 women (average 63 years of age, range 50 to 79; 83.9 percent White, 6.8 percent Black, 5.4 percent Hispanic, 3.9 percent Other) are presented in Table 2. These results reflect centrally adjudicated data after an average follow-up of 5.6 years.
- Timing of the initiation of estrogen plus progestin therapy relative to the start of menopause may affect the overall risk benefit profile. The WHI estrogen plus progestin substudy stratified by age showed in women 50 to 59 years of age a non-significant trend toward reduced risk for overall mortality .

### Women's Health Initiative Memory Study
- The WHIMS estrogen-alone ancillary study of WHI enrolled 2,947 predominantly healthy postmenopausal women 65 to 79 years of age and older (45 percent were 65 to 69 years of age; 36 percent were 70 to 74 years of age; 19 percent were 75 years of age and older) to evaluate the effects of daily CE (0.625 mg)-alone on the incidence of probable dementia (primary outcome) compared to placebo.
- After an average follow-up of 5.2 years, the relative risk of probable dementia for CE-alone versus placebo was 1.49 (95 percent CI, 0.832.66). The absolute risk of probable dementia for CE-alone versus placebo was 37 versus 25 cases per 10,000 women-years. Probable dementia as defined in this study included Alzheimer disease (AD), vascular dementia (VaD) and mixed type (having features of both AD and VaD). The most common classification of probable dementia in the treatment group and the placebo group was AD. Since the ancillary study was conducted in women 65 to 79 years of age, it is unknown whether these findings apply to younger postmenopausal women.
- The WHIMS estrogen plus progestin ancillary study enrolled 4,532 predominantly healthy postmenopausal women 65 years of age and older (47 percent were 65 to 69 years of age; 35 percent were 70 to 74 years of age; 18 percent were 75 years of age and older) to evaluate the effects of daily CE (0.625 mg) plus MPA (2.5 mg) on the incidence of probable dementia (primary outcome) compared to placebo.
- After an average follow-up of 4 years, the relative risk of probable dementia for CE plus MPA was 2.05 (95 percent CI, 1.213.48). The absolute risk of probable dementia for CE plus MPA versus placebo was 45 versus 22 per 10,000 women-years. Probable dementia as defined in this study included AD, VaD and mixed type (having features of both AD and VaD). The most common classification of probable dementia in the treatment group and the placebo group was AD. Since the ancillary study was conducted in women 65 to 79 years of age, it is unknown whether these findings apply to younger postmenopausal women.
- When data from the two populations were pooled as planned in the WHIMS protocol, the reported overall relative risk for probable dementia was 1.76 (95 percent CI, 1.192.60). Differences between groups became apparent in the first year of treatment. It is unknown whether these findings apply to younger postmenopausal women.

# How Supplied
- NDC 0046-0749-05Each package provides one SECULE vial containing 25 mg of conjugated estrogens, USP, for injection (also lactose 200 mg, sodium citrate 12.2 mg, and simethicone 0.2 mg). The pH is adjusted with sodium hydroxide or hydrochloric acid.
- Premarin Intravenous (conjugated estrogens, USP) for injection is prepared by cryodesiccation.
- SECULE-Registered trademark to designate a vial containing an injectable preparation in dry form.

## Storage
There is limited information regarding Conjugated estrogens (injection) Storage in the drug label.

# Images

## Drug Images

## Package and Label Display Panel

# Patient Counseling Information
- Read this PATIENT INFORMATION which describes the benefit and major risks of your treatment, as well as how and when treatment should be used. This information does not take the place of talking to your healthcare provider about your medical condition or your treatment.

# Precautions with Alcohol
Alcohol-Conjugated estrogens interaction has not been established. Talk to your doctor about the effects of taking alcohol with this medication.

# Brand Names
- PREMARIN

# Look-Alike Drug Names
There is limited information regarding Conjugated estrogens (injection) Look-Alike Drug Names in the drug label.

# Drug Shortage Status

# Price