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PREMARIN Tablets (conjugated estrogens)

Health Professional Information

SUMMARY PRODUCT INFORMATION

Route of Administration

Dosage Form / Strength

Clinically Relevant Nonmedicinal Ingredients

oral

conjugated estrogens sustained release tablets

Lactose

For a complete listing see Dosage Forms, Composition and Packaging section.

 

Indications And Clinical Use

PREMARIN® (conjugated estrogens sustained release tablets) is indicated for the following:

  1. the relief of menopausal and postmenopausal symptoms occurring in naturally or surgically induced estrogen deficiency states including vulvar and vaginal atrophy.
  2. the prevention of osteoporosis in naturally occurring or surgically induced estrogen- deficiency states. When prescribing solely for the prevention of postmenopausal osteoporosis, therapy with PREMARIN should be considered in light of other available therapies (see Boxed Warning) and should only be considered for women at significant risk of osteoporosis. Non-estrogen medications should be carefully considered. For older women who are not experiencing any more acute symptoms of menopause, use in combination with a progestin should only be considered for women who failed on, or were intolerant of, non-estrogen medication. Adequate diet, calcium and vitamin D intake, cessation of smoking, as well as regular physical weight-bearing exercise are required in addition to the administration of PREMARIN. Postmenopausal women require an average of 1000 mg to 1500 mg/day of elemental calcium. Therefore, when not contraindicated, calcium supplementation may be helpful for women with suboptimal dietary intake. Vitamin D supplementation of 400-800 IU/day may also be required to ensure adequate daily intake in postmenopausal women.
  3. hypoestrogenism due to hypogonadism, castration, or primary ovarian failure.
  4. atrophic vaginitis
  5. vulvar atrophy (with or without pruritis). When prescribing solely for the treatment of symptoms of vulvar and vaginal atrophy, topical vaginal products should be considered.

In patients with an intact uterus, PREMARIN should be prescribed with an appropriate dosage of a progestin for women with intact uteri, in order to prevent endometrial hyperplasia/carcinoma.

Geriatrics (> 65 years of age): See above indications.

Pediatrics (< 16 years of age): Clinical studies have not been conducted in the pediatric population. PREMARIN is not indicated for use in children.

Contraindications

PREMARIN (conjugated estrogens sustained release tablets) is contraindicated in the following conditions:

  • Patients who are hypersensitive to this drug or to any ingredient in the formulation or component of the container. For a complete listing, see the Dosage Forms, Composition and Packaging section of the product monograph.
  • Liver dysfunction or disease as long as liver function tests have failed to return to normal.
  • Known or suspected estrogen-dependent malignant neoplasia (e.g. endometrial cancer).
  • Endometrial hyperplasia.
  • Known, suspected, or past history of breast cancer.
  • Undiagnosed abnormal genital bleeding.
  • Known or suspected pregnancy (see WARNINGS AND PRECAUTIONS, Special Populations, Pregnant Women)
  • Active or past history of confirmed venous thromboembolism (such as deep venous thrombosis or pulmonary embolism) or active thrombophlebitis.
  • Active or past history of arterial thromboembolic disease (e.g. stroke, myocardial infarction, coronary heart disease).
  • Partial or complete loss of vision due to ophthalmic vascular disease.
  • Known thrombophilic disorders (e.g. protein C, protein S, or antithrombin deficiency).
  • Migraine with or without aura

Warnings And Precautions

Serious Warnings and Precautions

The Women’s Health Initiative (WHI) trial examined the health benefits and risks of oral combined estrogen plus progestin therapy (n=16,608) and oral estrogen-alone therapy (n=10,739) in postmenopausal women aged 50 to 79 years.

The estrogen plus progestin arm of the WHI trial (mean age 63.3 years) indicated an increased risk of myocardial infarction (MI), stroke, invasive breast cancer, pulmonary emboli and deep vein thrombosis in postmenopausal women receiving treatment with combined conjugated equine estrogens (CEE, 0.625 mg/day) and medroxyprogesterone acetate (MPA, 2.5 mg/day) for 5.2 years compared to those receiving placebo.

The estrogen-alone arm of the WHI trial (mean age 63.6 years) indicated an increased risk of stroke and deep vein thrombosis in hysterectomized women treated with CEE-alone (0.625 mg/day) for 6.8 years compared to those receiving placebo.

Therefore, the following should be given serious consideration at the time of prescribing:

  • Estrogens with or without progestins should not be prescribed for primary or secondary prevention of cardiovascular diseases.
  • Estrogens with or without progestins should be prescribed at the lowest effective dose for the approved indication.
  • Estrogens with or without progestins should be prescribed for the shortest period possible for the approved indication.
  • The use of PREMARIN for the prevention of osteoporosis should be considered in light of other available therapies.

General

For the treatment of postmenopausal symptoms, HRT should only be initiated for symptoms/conditions that are consistent with the indications (see INDICATIONS AND CLINICAL USE). In all cases, a careful appraisal of the risks and benefits should be undertaken at least annually and HRT should only be continued as long as the benefit outweighs the risks.”

Combined Estrogen and Progestin Therapy:
There are additional and/or increased risks that may be associated with the use of combination estrogen-plus-progestin therapy compared with using estrogen-alone regimens. These include an increased risk of myocardial infarction, pulmonary embolism, invasive breast cancer and ovarian cancer.

Carcinogenesis and Mutagenesis

Breast cancer
Available epidemiological data indicate that the use of combined estrogen plus progestin by postmenopausal women is associated with an increased risk of invasive breast cancer.

In the estrogen plus progestin arm of the WHI trial, among 10,000 women over a one-year period, there were:

  • 8 more cases of invasive breast cancer (38 on combined HRT versus 30 on placebo).

The WHI study also reported that the invasive breast cancers diagnosed in the estrogen plus progestin group were similar in histology but were larger (mean [SD], 1.7 cm [1.1] vs 1.5 cm [0.9], respectively; P=0.04) and were at a more advanced stage compared with those diagnosed in the placebo group. The percentage of women with abnormal mammograms (recommendations for short-interval follow-up, a suspicious abnormality, or highly suggestive of malignancy) was significantly higher in the estrogen plus progestin group versus the placebo group. This difference appeared at year one and persisted in each year thereafter.

In the estrogen-alone arm of the WHI trial, there was no statistically significant difference in the rate of invasive breast cancer in hysterectomized women treated with conjugated equine estrogens versus women treated with placebo.

It is recommended that estrogens not be given to women with existing breast cancer or those with a previous history of the disease (see CONTRAINDICATIONS).

There is a need for caution in prescribing estrogens for women with known risk factors associated with the development of breast cancer, such as strong family history of breast cancer (first degree relative) or who present a breast condition with an increased risk (abnormal mammograms and/or atypical hyperplasia at breast biopsy).

Other known risk factors for the development of breast cancer such as nulliparity, obesity, early menarche, late age at first full term pregnancy and at menopause should also be evaluated.

It is recommended that women undergo mammography prior to the start of HRT treatment and at regular intervals during treatment, as deemed appropriate by the treating physician and according to the perceived risks for each patient.

The overall benefits and possible risks of hormone replacement therapy should be fully considered and discussed with patients. It is important that the modest increased risk of being diagnosed with breast cancer after 4 years of treatment with combined estrogen plus progestin HRT (as reported in the results of the WHI trial) be discussed with the patient and weighed against its known benefits.

Instructions for regular self-examination of the breasts should be included in this counselling.

Endometrial hyperplasia & endometrial carcinoma
Estrogen-only HRT increases the risk of endometrial hyperplasia/carcinoma if taken by women with intact uteri. Estrogen should be prescribed with an appropriate dosage of a progestin for women with intact uteri in order to prevent endometrial hyperplasia/carcinoma.

The reported endometrial cancer risk among unopposed estrogen users is about 2- to 12-fold or greater than in non-users and appears to be dependent on duration of treatment and on estrogen dose. The greatest risk appears associated with prolonged use, with increased risks of 15- to 24- fold for five years or more, and this risk has been shown to persist for at least 8 to15 years after ERT is discontinued.

Clinical surveillance of all women taking combined estrogen plus progestin HRT is important. Adequate diagnostic measures, including endometrial sampling when indicated, should be undertaken to rule out malignancy in all cases of undiagnosed persistent or recurring abnormal vaginal bleeding.

There is no evidence that the use of natural estrogens results in a different endometrial risk profile than synthetic estrogens of equivalent estrogen dose. Adding a progestin to postmenopausal estrogen therapy has been shown to reduce the risk of endometrial hyperplasia, which may be a precursor to endometrial cancer.

Ovarian cancer
In some epidemiologic studies, the use of estrogen therapy has been associated with an increased risk of ovarian cancer over multiple years of use. Other epidemiologic studies have not found these associations.

Cardiovascular

Cardiovascular risk
ERT has been reported to increase the risk of stroke and deep venous thrombosis (DVT).

Risk factors for cardiovascular disease (e.g., hypertension, diabetes mellitus, tobacco use, hypercholesterolemia, and obesity) should be managed appropriately.

The results of the Heart and Estrogen/progestin Replacement Studies (HERS and HERS II) and the Women’s Health Initiative (WHI) trial indicate that the use of estrogen plus progestin is associated with an increased risk of coronary heart disease (CHD) in postmenopausal women. The results of the WHI trial indicate that the use of estrogen-alone and estrogen plus progestin is associated with an increased risk of stroke in postmenopausal women.

Patients who are at risk of developing migraines with aura may be at risk of ischemic stroke and should be kept under careful observation.

Should a stroke occur or be suspected, PREMARIN should be discontinued immediately.

WHI trial findings
In the combined estrogen plus progestin arm of the WHI trial, among 10,000 women over a one- year period, there were:

  • 8 more cases of stroke (29 on combined HRT versus 21 on placebo)
  • 7 more cases of CHD (37 on combined HRT versus 30 on placebo).

In the estrogen-alone arm of the WHI trial of women with prior hysterectomy, among 10,000 women over a one-year period, there were/was:

  • 12 more cases of stroke (44 on estrogen-alone therapy versus 32 on placebo)
  • no statistically significant difference in the rate of CHD.

HERS and HERS II findings
In the Heart and Estrogen/progestin Replacement Study (HERS) of postmenopausal women with documented heart disease (n=2763, average age 66.7 years), a randomized placebo-controlled clinical trial of secondary prevention of coronary heart disease (CHD), treatment with 0.625 mg/day oral conjugated equine estrogen (CEE) plus 2.5 mg oral medroxyprogesterone acetate (MPA) demonstrated no cardiovascular benefit. Specifically, during an average follow-up of 4.1 years, treatment with CEE 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 hormone-treated group than in the placebo group in year 1, but not during the subsequent years.

From the original HERS trial, 2321 women consented to participate in an open label extension of HERS known as HERS II. Average follow-up in HERS II was an additional 2.7 years, for a total of 6.8 years overall. After 6.8 years, hormone therapy did not reduce the risk of cardiovascular events in women with CHD.

Blood pressure
Women using hormone replacement therapy sometimes experience increased blood pressure. Blood pressure should be monitored with HRT use. Elevation of blood pressure in previously normotensive or hypertensive patients should be investigated and HRT may have to be discontinued.

Endocrine and Metabolism

Glucose and lipid metabolism
Women with familial hyperlipidemias need special surveillance. Lipid-lowering measures are recommended additionally, before treatment is started.

A worsening of glucose tolerance and lipid metabolism has been observed in a significant percentage of peri- and post-menopausal patients. Therefore, diabetic patients, or those with a predisposition to diabetes, should be observed closely to detect any alterations in carbohydrate or lipid metabolism, especially in triglyceride blood levels.

Caution should be exercised in patients with pre-existing hypertriglyceridemia since rare cases of large increases of plasma triglycerides leading to pancreatitis have been reported with estrogen therapy in this population.

Heme metabolism
Women with porphyria need special surveillance.

Estrogens should be used with caution in individuals with pre-existing severe hypocalcemia.

Calcium and phosphorus metabolism
Because the prolonged use of estrogens influences the metabolism of calcium and phosphorus, estrogens should be used with caution in patients with metabolic and malignant bone diseases associated with hypercalcemia and in patients with renal insufficiency.

Estrogen therapy should be used with caution in individuals with hypoparathyroidism as estrogen-induced hypocalcemia may occur.

If hypercalcemia occurs, use of the drug should be stopped and appropriate measures should be taken to reduce the serum calcium level.

Hypothyroidism
Estrogen administration leads to increased thyroid-binding globulin (TBG) levels. Patients who require thyroid hormone replacement therapy and who are also taking estrogen may required increased doses of their thyroid replacement therapy. These women should have their thyroid function monitored in order to maintain their free thyroid hormone levels remain in an acceptable range (see Drug-Laboratory Test Interactions).

Other conditions
PREMARIN contains lactose. In patients with rare hereditary galactose intolerance, lactase deficiency or gIucose-galactose malabsorption, the severity of the condition should be taken into careful consideration before prescribing PREMARIN. The patient should be closely monitored.

Genitourinary

Endometriosis
Endometriosis may be exacerbated with administration of estrogen therapy. 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.

Uterine Leiomyomata
Pre-existing uterine leiomyomata may increase in size during estrogen use. Growth, pain or tenderness of uterine leiomyomata requires discontinuation of medication and appropriate investigation.

Vaginal bleeding
Abnormal vaginal bleeding, due to its prolongation, irregularity or heaviness, occurring during therapy should prompt appropriate diagnostic measures to rule out the possibility of uterine malignancy and the treatment should be re-evaluated.

Hematologic

Venous thromboembolism
Available epidemiological data indicate that use of estrogen with or without progestin by postmenopausal women is associated with an increased risk of developing venous thromboembolism (VTE).

In the estrogen plus progestin arm of the WHI trial, among 10,000 women on combined HRT over a one-year period, there were 18 more cases of venous thromboembolism, including 8 more cases of pulmonary embolism.

In the estrogen-alone arm of the WHI trial, among 10,000 women on estrogen therapy over a one-year period, there were 7 more cases of venous thromboembolism, although there was no statistically significant difference in the rate of pulmonary embolism.

Generally recognized risk factors for VTE include a personal history, a family history (the occurrence of VTE in a direct relative at a relatively early age may indicate genetic predisposition), severe obesity (body mass index > 30 kg/m2) and systemic lupus erythematosus. The risk of VTE also increases with age and smoking.

The risk of VTE may be temporarily increased with prolonged immobilization, major surgery or trauma. In women on HRT, attention should be given to prophylactic measures to prevent VTE following surgery. Also, patients with varicose veins should be closely supervised. The physician should be alert to the earliest manifestations of thrombotic disorders (thrombophlebitis, retinal thrombosis, cerebral embolism and pulmonary embolism). If these occur or are suspected, PREMARIN should be discontinued immediately, given the risks of long-term disability or fatality.

If feasible, PREMARIN should be discontinued at least 4 weeks before major surgery which may be associated with an increased risk of thromboembolism, or during periods of prolonged immobilization.

Hepatic/Biliary/Pancreatic

Liver disorders
Patients who have previously had liver disorders such as liver adenoma should be closely supervised as this condition may recur or be aggravated during treatment with PREMARIN.

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

Hepatic hemangiomas
Particular caution is indicated in women with hepatic hemangiomas, as HRT may cause an exacerbation of this condition.

Jaundice
Caution is advised in patients with a history of liver and/or biliary disorders. If cholestatic jaundice develops during treatment, the treatment should be discontinued and appropriate investigations carried out. Estrogens may be poorly metabolized in patients with impaired liver function.

Liver function tests
Liver function tests should be done periodically in subjects who are suspected of having hepatic disease. For information on endocrine and liver function tests, see Monitoring and Laboratory Tests.

Immune

Systemic lupus erythematosus
Particular caution is indicated in women with systemic lupus erythematosus, as HRT may cause an exacerbation of this condition.

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

Anaphylactic Reaction and Angioedema
Cases of anaphylaxis, which developed within minutes to hours after taking PREMARIN 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 taking PREMARIN. 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 should not receive PREMARIN again.

Exogenous estrogens may exacerbate symptoms of angioedema in women with hereditary angioedema.

Neurologic

Cerebrovascular insufficiency
Patients who develop visual disturbances, classical migraine, transient aphasia, paralysis or loss of consciousness should discontinue medication.

Patients with a previous history of classical migraine and who develop a recurrence or worsening of migraine symptoms should be reevaluated.

Ophthalmologic
If visual abnormalities develop: Discontinue PREMARIN 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, PREMARIN should be withdrawn. Retinal vascular thrombosis has been reported in patients receiving estrogens with or without progestins.

Dementia
Available epidemiological data indicate that the use of combined estrogen plus progestin in women age 65 and over may increase the risk of developing probable dementia.

The Women's Health Initiative Memory Study (WHIMS), a clinical substudy of the WHI, was designed to assess whether postmenopausal hormone replacement therapy (oral estrogen plus progestin or oral estrogen-alone) reduces the risk of dementia in women aged 65 and over (age range 65-79 years) and free of dementia at baseline.

It is unknown whether these findings apply to younger postmenopausal women (see Special Populations, Geriatrics).

In the estrogen plus progestin arm of the WHIMS (n=4532), women with intact uteri were treated with daily 0.625 mg conjugated equine estrogens (CEE) plus 2.5 mg medroxyprogesterone acetate (MPA) or placebo for an average of 4.05 years. The results, when extrapolated to 10,000 women treated over a one-year period showed:

  • 23 more cases of probable dementia (45 on combined HRT versus 22 on placebo).

In the estrogen-alone arm of the WHIMS (n=2947), women with prior hysterectomy were treated with daily 0.625 mg CEE or placebo for an average of 5.21 years. The results, when extrapolated to 10,000 women treated over a one-year period showed:

  • 12 more cases of probable dementia (37 on estrogen-alone versus 25 on placebo), although this difference did not reach statistical significance.

When data from the estrogen plus progestin arm of the WHIMS and the estrogen-alone arm of the WHIMS were combined, as per the original WHIMS protocol, in 10,000 women over a one- year period, there were:

  • 18 more cases of probable dementia (41 on estrogen plus progestin or estrogen-alone versus 23 on placebo).

Epilepsy
Particular caution is indicated in women with epilepsy, as HRT may cause an exacerbation of this condition.

Ear/Nose/Throat

Otosclerosis
Estrogens should be used with cautions in patients with otosclerosis.

Psychiatric

Depression
Patients who are taking progestogens and have a history of depression should be observed. If the depression occurs to a serious degree, the drug should be discontinued.

Renal

Fluid retention
Estrogens may cause fluid retention.

Therefore, particular caution is indicated in cardiac, renal dysfunction, or asthma. If, in any of the above-mentioned conditions, a worsening of the underlying disease is diagnosed or suspected during treatment, the benefits and risks of treatment should be reassessed based on the individual case.

Special Populations

Pregnant Women: PREMARIN is contraindicated during pregnancy (see CONTRAINDICATIONS). If pregnancy occurs during medication with PREMARIN treatment should be withdrawn immediately.

Nursing Women: Estrogen administration to nursing mothers has been shown to decrease the quantity and quality of breast milk. Detectable amounts of estrogens have been identified in the milk of mothers receiving the drug. Where an assessment of the risk to benefit ratio suggests the use of this product in nursing women is unfavourable, formula feeding should be substituted for breast feeding.

Pediatrics (< 16 years of age): PREMARIN is not indicated for use in children. Safety and effectiveness in pediatric patients have not been established.

Large and repeated doses of estrogens over an extended time period have been shown to accelerate epiphyseal closure, which could result in short stature if treatment is initiated before the completion of physiologic puberty in normally developing children. If estrogens are administered to patients whose bone growth is not complete, periodic monitoring of bone maturation and effects on epiphyseal centers is recommended during administration of estrogens.

Estrogen treatment of prepubertal girls also induces premature breast development and vaginal cornification, and may induce vaginal bleeding. (See INDICATIONS AND CLINICALUSE and DOSAGE AND ADMINISTRATION).

Geriatrics (> 65 years of age): There have not been sufficient numbers of geriatric women involved in clinical studies utilizing PREMARIN to determine whether those over 65 years of age differ from younger subjects in their response to PREMARIN.

The Women’s Health Initiative Study
In the Women’s Health Initiative (WHI) estrogen-alone substudy (daily [0.625 mg] versus placebo), there was a higher relative risk of stroke in women greater than 65 years of age.

In the WHI estrogen plus progestin substudy (daily CE [0.625 mg] plus MPA [2.5 mg] versus placebo), there was a higher relative risk of nonfatal stroke and invasive breast cancer in women older than 65 years of age.

The Women’s Health Initiative Memory Study
In the WHIMS ancillary studies of postmenopausal women 65 to 79 years of age, there was an increased risk of developing probable dementia in women receiving estrogen-alone or estrogen plus progestin when compared to placebo.

Since both ancillary studies were conducted in women 65 to 79 years of age, it is unknown whether these findings apply to younger postmenopausal women.

Information for Patients

No studies on the effect of ability to drive or use machines have been performed.

Monitoring and Laboratory Tests

Before PREMARIN is administered, the patient should have a complete physical examination including blood pressure determination. Breasts and pelvic organs should be appropriately examined and a Papanicolaou smear should be performed. Endometrial biopsy should be done only when indicated. Baseline tests should include mammography, measurements of blood glucose, calcium, triglycerides and cholesterol, and liver function tests. Before starting treatment pregnancy should be excluded. Periodic check-ups and careful benefit/risk evaluations should be undertaken in women treated with ERT/HRT therapy. The first follow-up examination should be done within three to six months of initiation of treatment to assess response to treatment. Thereafter, examinations should be made at intervals of at least once a year. Appropriate investigations should be arranged at regular intervals as determined by the physician.

Mammography examinations should be scheduled based on patient age, risk factors and prior mammogram results.

The importance of regular self-examination of the breasts should be discussed with the patient.

Adverse Reactions

Adverse Drug Reaction Overview

See Warnings/Precautions regarding potential induction of malignant neoplasia and other adverse effects similar to those observed with oral contraceptives.

The following additional adverse reactions have been reported with estrogen replacement therapy or are undesirable effects associated with hormone replacement therapy:

Blood and lymphatic system disorders

Altered coagulation tests (see WARNINGS AND PRECAUTIONS, Drug-Laboratory Tests Interactions).

Cardiac disorders

Palpitations; increase in blood pressure (see WARNINGS AND PRECAUTIONS); coronary thrombosis, myocardial infarction.

Endocrine disorders

Increased blood sugar levels; decreased glucose tolerance, carbohydrate tolerance

Eye disorders

Neuro-ocular lesions (e.g. retinal vascular thrombosis, optic neuritis); visual disturbances; steepening of the corneal curvature; intolerance to contact lenses.

Gastrointestinal disorders

Nausea; vomiting; abdominal discomfort (cramps, pressure, pain), bloating, pancreatitis, gallbladder disorder; ischemic colitis.

General disorders and administration site conditions

Fatigue; changes in appetite; changes in body weight; changes in libido, exacerbation of porphyria, hypocalcemia (in patients with disease that can predispose to severe hypocalcemia), exacerbation of asthma, angioedema, hypersensitivity; anaphylactic/anaphlactoid reactions, increased triglycerides.

Hepatobiliary disorders

Gallbladder disorder; cholestatic jaundice.

Musculoskeletal and connective tissue disorders

Musculoskeletal pain including leg pain not related to thromboembolic disease (usually transient, lasting 3-6 weeks) may occur, arthralgia, leg cramps.

Neoplasms, benign

Fibrocystic breast changes; enlargement of hepatic hemangiomas.

Nervous system disorders

Aggravation of migraine episodes; headaches; dizziness; cerebrovascular accident/stroke, exacerbation of epilepsy, stroke, exacerbation of chorea, somnolence, insomnia.

Psychiatric disorders

Mental depression; nervousness; irritability, anxiety, mood disturbances, dementia, fatigue.

Renal and urinary disorders

Cystitis; dysuria; sodium retention; edema.

Reproductive system and breast disorders

Breakthrough bleeding; spotting; change in menstrual flow and abnormal withdrawal bleeding or flow, dysmenorrheal/pelvic pain; vaginal itching/discharge; dyspareunia; endometrial hyperplasia; pre-menstrual-like syndrome; reactivation of endometriosis; changes in cervical erosion and amount of cervical secretion; vaginal candidiasis, amenorrhea, vaginitis, increase in size of uterine leiomyomata, breast swelling and tenderness, breast pain, enlargement, galactorrhea, breast discharge; growth potentiation of benign meningioma; leukorrhea.

Skin and subcutaneous tissue disorders

Chloasma or melasma, which may persist when drug is discontinued; erythema multiforme; erythema nodosum; haemorrhagic eruption; loss of scalp hair; hirsutism and acne, urticaria, pruritus, generalized rash, rash (allergic) with without pruritus, alopecia.

Vascular disorders

Isolated cases of: thrombophlebitis; thromboembolic disorders, venous thrombosis.

Clinical Trial Adverse Drug Reactions

Because clinical trials are conducted under very specific conditions the adverse drug reaction rates observed in the clinical trials may not reflect the rates observed in practice and should not be compared to the rates in the clinical trials of another drug. Adverse drug reaction information from clinical trials is useful for identifying drug-related adverse events and for approximating rates.

A phase III double-blind, randomized study was conducted to compare the efficacy and safety of various regimens of PREMARIN (conjugated estrogens) and medroxyprogesterone acetate (MPA). Efficacy was determined by the incidence of endometrial hyperplasia at the twelve month evaluation. A total of 1,724 generally healthy postmenopausal women (mean age, 54.0 years ± SD 4.6) participated in the study. The patients were considered as having completed the study if they participated in all 13 cycles (28 days/cycle). The five arms in the study were: 2 for Premplus®, 2 for Premplus Cycle®, and 1 for PREMARIN alone.

Prior to treatment, the following were performed: physical examinations, vital signs, papanicolaou smear, laboratory safety screen, mammography, follicle stimulating hormone (FSH), and endometrial biopsy. During the patient visit for Cycle 6, all but the mammography and FSH were performed. At the end of the study, Cycle 13, all but the FSH were performed.

No dose-dependent incidence of adverse experiences was seen in the multicenter efficacy and safety study. Significantly (p< 0.05) fewer (12%) PREMARIN treated patients reported breast pain than in the PREMARIN /MPA groups. Headache was the most common drug-related study event in the PREMARIN alone group, reported by 69 (20%) patients. Table 1 summarizes the treatment-emergent drug-related study events reported by 2% or more of the patients.

Table 1: Treatment-Emergent Drug-Related Study Events With an Incidence of ≥2%

Study Event

PREMARIN
0.625 mg CE
(n=347)

No. (%) of Patients +

General disorders and administration site conditions 
Asthenia18 (5)

Chest pain

2 (<1)

Generalized edema

9 (3)

Edema

5 (1)

Peripheral edema

11 (3)

Pain

11 (3)

Vascular disorders 
Hypertension7 (2)

Vasodilatation

9 (3)

Gastrointestinal disorders 
Diarrhea

6 (2)

Dyspepsia

4 (1)

Flatulence

14 (4)b

Nausea

19 (5)

Abdominal pain

46 (13)

Musculoskeletal connective tissue,and bone disorders 
Leg cramps8 (2)

Back pain

13 (4)

Nervous system disorders 
Headache69 (20)

Depression

22 (6)

Migraine

7 (2)

Dizziness

10 (3)

Emotional lability

4 (1)

Insomnia

2 (<1)

Nervousness

1 (<1)b, d

Skin and subcutaneous tissue disorders 
Acne6 (2)
Pruritus6 (2)a, b
Rash5 (1)
Reproductive system and breast disorders 
Breast enlargement4 (1)a, b

Breast pain *

40 (12)a, b, d

Cervix disorder**

12 (3)

Dysmenorrhea

17 (5)d

Endometrial hyperplasia

57 (20)

Leukorrhea

24 (7)

Menstrual disorder

3 (<1)

Pelvic pain

16 (5)

Uterine spasm

0 (0)a, d

Vaginal bleeding ***

28 (8)b

Vaginitis

4 (1)a, b

Investigations 
Pap smear abnormal0 (0)a
Weight increased10 (3)
Psychiatric disorders 
Depression22 (6)

Emotional lability

4 (1)

Nervousness

1 (<1)b,d

+ Patients were counted only once for a particular study event.
* Breast pain also includes breast discomfort, breast soreness, breast tenderness, mastodynia, nipple soreness and nipple tenderness.
** Cervix disorder includes cervical dysplasia, cervical erosion, cervical hypersecretion.
† Pap smear abnormal refers to positive Pap smear class III through V.
*** Vaginal bleeding includes menorrhagia, metrorrhagia, uterine hemorrhage, and vaginal hemorrhage.
a, b, d, = Significant difference ( p < 0.05) from treatment group Premplus® (0.625/2.5 mg), Premplus® (0.625/5.0 mg), Premplus Cycle® (0.625/10.0 mg) and PREMARIN (0.625 mg) respectively.

The above Table 1 summarizes the treatment-emergent drug-related study events reported by greater than 2% of the patients. The number of patients with any study event is not necessarily the sum of the individual events since a patient might have reported two or more different study events. The addition of progestin to estrogen replacement therapy may contribute to breast pain. This is reflected by the greater percentage of patients with breast pain on combination therapy than on PREMARIN alone.

If adverse symptoms persist, the prescription of HRT should be re-considered.

Post Marketing Adverse Drug Reactions

The following adverse reactions have been reported with PREMARIN tablets. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate the frequency or establish a causal relationship to drug exposure.

Genitourinary System
Abnormal uterine bleeding, dysmenorrhea/pelvic pain, increase in size of uterine leiomyomata, vaginitis, including vaginal candidiasis, change in cervical secretion, ovarian cancer, endometrial hyperplasia, endometrial cancer, leucorrhea.

Breasts
Tenderness, enlargement, pain, discharge, galactorrhea, fibrocystic breast changes, breast cancer, gynecomastia in males.

Cardiovascular
Deep and superficial venous thrombosis, pulmonary embolism, thrombophlebitis, myocardial infarction, stroke, increase in blood pressure.

Gastrointestinal
Nausea, vomiting, abdominal pain, 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, loss of scalp hair, hirsutism, pruritus, rash.

Eyes
Retinal vascular thrombosis, intolerance to contact lenses.

Central Nervous System
Headache, migraine, dizziness, mental depression, nervousness, mood disturbances, irritability, 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, angioedema, anaphylactoid/anaphylactic reactions, exacerbation of asthma, increased triglycerides, hypersensitivity.

Additional postmarketing adverse reactions have been reported in patients receiving other forms of hormone therapy.

Drug Interactions

Overview

Data from a drug-drug interaction study involving conjugated estrogens and medroxyprogesterone acetate indicate that the pharmacokinetic disposition of both drugs are not altered when the drugs are co-administered. Other clinical drug-drug interaction studies have not been conducted with conjugated estrogens.

Estrogens may diminish the effectiveness of anticoagulant, antidiabetic and antihypertensive agents.

Drug-Drug Interactions

The following section contains information on drug interactions with ethinyl estradiol-containing products (specifically, oral contraceptives) that have been reported in the public literature. The clinical significance of these drugs is unknown; additionally, it is unknown whether such interactions occur with drug products containing other types of estrogens. Monitoring of patient response to therapy is recommended.

Hepatic metabolism
Interactions can occur with drugs that induce microsomal enzymes which can decrease ethinyl estradiol concentrations (eg., rifampin, barbiturates, phenytoin, carbamazepine, troglitazone).

Gastrointestinal wall
Sulfation of ethinyl estradiol has been shown to occur in the gastrointestinal (GI) wall. Therefore, drugs which act as competitive inhibitors for sulfation in the GI wall may increase ethinyl estradiol bioavailability (eg., ascorbic acid, acetaminophen).

Interference in the metabolism of other drugs
Ethinyl estradiol may interfere with the metabolism of other drugs by inhibiting hepatic microsomal enzymes or by inducing hepatic drug conjugation, particularly glucuronidation. Increased plasma concentrations of cyclosporin, prednisolone, and theophylline have been reported with concomitant administration of certain drugs containing ethinyl estradiol (eg., oral contraceptives containing ethinyl estradiol). In addition, products containing ethinyl estradiol may induce the conjugation of other compounds.

Decreased plasma concentrations of acetaminophen and increased clearance of temazepam, salicylic acid, morphine, and clofibric acid have been noted when these drugs were administered with certain ethinyl estradiol-containing drug products (eg., oral contraceptives containing ethinyl estradiol).

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, phenytoin, carbamazepine, rifampicin, and dexamethasone 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 cimetidine, erythromycin, clarithromycin, ketoconazole, itraconazole, ritonavir and grapefruit juice, may increase plasma concentrations of estrogens and may result in side effects.

Other interactions with ethinyl estradiol
Coadministration of atorvastatin and certain ethinyl estradiol-containing drug products (eg., oral contraceptives) increase AUC values for ethinyl estradiol by 20 percent.

Clinical pharmacokinetic studies have not demonstrated any consistent effect of antibiotics (other than rifampin) on plasma concentrations of synthetic steroids.

Drug-Food Interactions
CYP3A4 inhibitors such as grapefruit juice may increase plasma concentrations of 17 ß-estradiol and may result in side effects.

A single dose study in healthy, postmenopausal women was conducted to investigate any potential drug interaction when 2 x 0.625 mg PREMARIN(conjugated estrogens) and 2.5 mg medroxyprogesterone acetate (MPA) tablets were administered immediately following a high-fat breakfast. Administration with food slowed the absorption of the conjugated estrogens, thereby reducing the Cmax of the various estrogens by 25% to 30%, and increasing MPA Cmax by 89% and AUC0-∞ by 28%. Thus, food slightly lowered the Cmax, but did not affect the AUC, of the estrogens from a 0.625 mg PREMARIN tablet; food significantly increased the Cmax and AUC of MPA from a 2.5-mg tablet.

Drug-Herb Interactions
It was found that some herbal products (e.g., St. John’s wort), which are available as over-the- counter (OTC) products, might interfere with steroid metabolism, and therefore alter the efficacy and safety of estrogen/progestin products. Hot flashes and vaginal bleeding have been reported in patients taking estrogen replacement therapy (ERT) and combined estrogen plus progestin therapy (HRT) and St. John’s Wort (Hypericum perforatum) preparations. St. John’s Wort may induce hepatic microsomal enzymes, which theoretically may result in reduced efficacy of ERT and HRT.

Physicians and other health care providers should be made aware of other non-prescription products concomitantly used by the patient, including herbal and natural products, obtained from the widely spread Health Stores.

Drug-Laboratory Test Interactions
The results of certain endocrine and liver function tests may be affected by estrogen-containing products:

  • increased prothrombin time and partial thromboplastin time; increased levels of fibrinogen and fibrinogen activity, increased coagulation factors VII, VIII, IX, X; increased norepinephrine-induced platelet aggregability; decreased antithrombin III;
  • increased thyroid-binding globulin (TBG) levels leading to increased circulating total thyroid hormone (T4) as measured by column or radioimmunoassay;T3 resin uptake is decreased, reflecting the elevated TBG; free T4 concentration is unaltered;
  • impaired glucose tolerance;
  • increased plasma HDL and HDL2 cholesterol subfraction concentrations, reduced LDL cholesterol concentrations, increased serum triglycerides and phospholipids concentration;
  • other binding proteins may be elevated in serum i.e., corticosteroid binding globulin (CBG), sex-hormone binding globulin (SHBG), leading to increased circulating corticosteroids and sex steroids respectively,; free or biologically active hormone concentrations are unchanged;
  • The response to metyrapone may be reduced.

The results of the above laboratory tests should not be considered reliable unless therapy has been discontinued for two to four weeks.

The pathologist should be informed that the patient is receiving hormone replacement therapy (HRT) when relevant specimens are submitted.

Drug-lifestyle interactions
Acute alcohol ingestion during HRT may lead to elevations in circulating estradiol levels.

Drug-Food Interactions

The absorption of estrogens from the PREMARIN tablets 1.25 mg is not affected by food. PREMARIN tablets may be taken without regard to meals (see DOSAGE AND ADMINISTRATION).

Dosage And Administration

Dosing Considerations

The benefits and risks of HRT must always be carefully weighed, including consideration of the emergence of risks as therapy continues. Use of estrogens alone or in combination with progestins therapy should be prescribed at the lowest effective doses and for the shortest duration consistent with treatment goals and risks for the individual woman. Patients should be re- evaluated periodically as clinically appropriate to determine if treatment is still necessary (see boxed Serious Warnings and Precautions). For women who have intact uteri, adequate diagnostic measures, such as endometrial sampling, when indicated, should be undertaken to rule out malignancy in cases of undiagnosed persistent or recurring abnormal vaginal bleeding. In the absence of comparable data, the risks of HRT should be assumed to be similar for all estrogens and estrogen/progestin combinations.

Hormone replacement therapy (HRT) involving either estrogen alone or estrogen plus progestin combined therapy should only be continued as the benefits outweigh the risks for the individual.

Recommended Dose and Dosage Adjustment

PREMARIN therapy may be given continuously with no interruption in therapy, or in cyclical regimens (regimens such as 25 days on drug followed by five days off drug) as is medically appropriate on an individualized basis.

Continuous, non-cyclic therapy may be indicated in hysterectomized women or in cases where the signs and symptoms of estrogen deficiency become problematic during the treatment-free interval. In women with an intact uterus, a progestin should be coadministered for a minimum of 10, but preferably at least 12 to 14 days per cycle to avoid overstimulation of the endometrium. In addition, progestin should be administered to minimize the occurrence of endometrial hyperplasia. Unexpected or abnormal vaginal bleeding in such patients requires institution of prompt diagnostic measures, such as endometrial biopsy or curettage to rule out the possibility of uterine malignancy. Since progestins are administered to reduce the risk of hyperplastic changes of the endometrium, patients without a uterus do not require a progestin for this purpose.

In some cases, hysterectomized women with a history of endometriosis may need a progestin, see WARNINGS AND PRECAUTIONS, Endometriosis.

For maintenance therapy one should always use the lowest dose that still proves effective. The requirement for hormone replacement therapy for menopausal symptoms should be reassessed periodically.

PREMARIN may be taken without regard to meals. Tablets should be taken whole; do not divide, crush, chew, or dissolve tablets in mouth.

Usual Dosage Range

Menopausal symptoms
Patients should be treated with the lowest effective dose. Generally, women should be started at 0.3 mg PREMARIN daily, cyclically or continuously as is medically required. Adjust dosage according to severity of symptoms and response of the patient. For maintenance, adjust dosage to lowest level providing effective control.

Osteoporosis (loss of bone mass)
Patients should be treated with the lowest effective dose. Generally, women should be started at 1.3 mg PREMARIN daily. Subsequent dosage adjustments may be made based upon the individual clinical and bone mineral density responses. This dose should be periodically reassessed by the healthcare provider.

Hypoestrogenism due to

  1. Female hypogonadism: 0.3 mg to 0.625 mg daily, administered cyclically (e.g., 3 weeks on and 1 week off) or continuously as required. Doses are adjusted depending on the severity of symptoms and responsiveness of the endometrium.
  2. Female castration or primary ovarian failure: 1.25 mg daily, cyclically or continuously as required. Adjust dosage according to severity of symptoms and response of the patient. For maintenance, adjust dosage to lowest level that will provide effective control.

Atrophic Vaginitis
Patients should be treated with the lowest effective dose. Generally, women should be started at 0.3 mg PREMARIN daily depending upon the tissue response of the individual patient. Administer cyclically or continuously as required.

Vulvar Atrophy
Patients should be treated with the lowest effective dose. Generally, women should be started at 0.3 mg PREMARIN daily depending upon the tissue response of the individual patient. Administer cyclically or continuously as required.

Administration

Oral
PREMARIN should be prescribed with an appropriate dosage of a progestin for women with intact uteri in order to prevent endometrial hyperplasia/carcinoma. Progestin therapy is not required as part of hormone replacement therapy in women who have had a previous hysterectomy.

Missed Dose

If a patient misses a dose, advise them to take the dose as soon as possible. If it is almost time for the patient’s next dose, advise the patient to skip the missed dose and go back to their normal schedule. Patients should not take 2 doses at the same time.

Overdosage

Symptoms of overdose

Numerous reports of ingestion of large doses of estrogen products and estrogen-containing oral contraceptives by young children have not revealed acute serious ill effects.

Overdosage with estrogen may cause nausea, breast discomfort, fluid retention, bloating or vaginal bleeding in women.

Treatment of overdose

There is no specific antidote and further treatment if necessary should be symptomatic.

For management of a suspected drug overdose, contact your regional Poison Control Centre.

Action And Clinical 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 μg 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 estrogens 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.

Pharmacodynamics

Conjugated estrogens used in therapy are soluble in water and are well absorbed through the skin, mucous membranes, and gastrointestinal tract after release from the drug formulation.

Effects on vasomotor symptoms associated with estrogen deficiency
Hot flushes, feelings of intense heat over the upper trunk and face, with flushing of the skin and sweating occur in approximately 80% of women as a result of the decrease in ovarian hormones. These vasomotor symptoms are seen in women whether menopause is surgically induced or spontaneous. However, hot flushes may be more severe in women who undergo surgical menopause. Hot flushes can begin before the cessation of menses.

Effects on Osteoporosis associated with estrogen deficiency
For several years following natural or induced menopause, the rate of bone mass decline is accelerated. Conjugated estrogens reduce bone resorption and retard postmenopausal bone loss. Case-control studies have shown a reduction of up to 60% in hip and wrist fractures in women whose estrogen replacement was begun within a few years of menopause. Studies also suggest that estrogen reduces the rate of vertebral fractures. One clinical study demonstrated that even when estrogen was started as late as fifteen years after menopause, further loss of bone mass was prevented, but was not restored to premenopausal levels. The effect on bone mass conservation is sustained only as long as conjugated estrogens therapy is continued.

Effects on female hypogonadism
In clinical studies of delayed puberty due to female hypogonadism, breast development was induced by doses as low as 0.15 mg. The dosage may be gradually titrated upward at 6 to 12- month intervals as needed to achieve appropriate bone age advancement and eventual epiphyseal closure. Available data suggest that chronic dosing with 0.625 mg is sufficient to induce artificial cyclic menses with sequential progestin treatment and to maintain bone mineral density after skeletal maturity is achieved.

Effects on the Endometrium
The use of unopposed estrogen therapy has been associated with an increased risk of endometrial hyperplasia, a possible precursor of endometrial adenocarcinoma. The results of clinical studies indicate that the addition of a progestin to an estrogen replacement regimen for more than 10 days per cycle reduces the incidence of endometrial hyperplasia and the attendant risk of adenocarcinoma in women with intact uteri. The addition of a progestin into an estrogen replacement regimen has not been shown to interfere with the efficacy of estrogen replacement therapy for its approved indications.

Effect on bleeding patterns
With a continuous therapy, several bleeding patterns may occur. These may range from absence of bleeding to irregular bleeding. If bleeding occurs, it is frequently light spotting or moderate bleeding.

Pharmacokinetics

Absorption
Conjugated estrogens are soluble in water and are well absorbed from the gastrointestinal tract after release from the drug formulation. The PREMARIN tablet releases conjugated estrogens slowly over several hours. Table 2-1 and 2-2 summarize the mean pharmacokinetic parameters for unconjugated and conjugated estrogens following administration of 1 x 0.625 mg and 1 x 1.25 mg tablets to healthy postmenopausal women.

The pharmacokinetics of PREMARIN 1.25 mg tablets was assessed following a single dose with a high-fat breakfast and with fasting administration. These data demonstrate that the absorption of estrogens from the 1.25 mg tablets is not affected by food and that it may be taken without regard to meals.

Table 2-1: Pharmacokinetic Profile of Unconjugated and Total Estrogens Following a Dose of 1 x 0.625 mg

PK Parameter Arithmetic
Mean (%CV)

Cmax
(pg/mL)

tmax
(h)

t1/2
(h)

AUC

(pg•h/mL)

Estrone

87 (33)

9.6 (33)

50.7 (35)

5557 (59)

Baseline-adjusted estrone

64 (42)

9.6 (33)

20.2 (40)

1723 (52)

Equilin

31 (38)

7.9 (32)

12.9 (112)

602 (54)

Total estrone

2.7 (43)

6.9 (25)

26.7 (33)

75 (52)

Baseline-adjusted total estrone

2.5 (45)

6.9 (25)

14.8 (35)

46 (48)

Total equilin

1.8 (56)

5.6 (45)

11.4 (31)

27 (56)

Table 2-2: Pharmacokinetic Profile of Unconjugated and Total Estrogens Following a Dose of 1 x 1.25 mg

PK Parameter Arithmetic Mean
(%CV)

Cmax
(pg/mL)

tmax
(h)

t1/2
(h)

AUC

(pg•h/mL)

Estrone

124 (30)

10.0 (32)

38.1 (37)

6332 (44)

Baseline-adjusted estrone

102 (35)

10.0 (32)

19.7 (48)

3159 (53)

Equilin

59 (43)

8.8 (36)

10.9 (47)

1182 (42)

Total estrone

4.5 (39)

8.2 (58)

26.5 (40)

109 (46)

Baseline-adjusted total estrone

4.3 (41)

8.2 (58)

17.5 (41)

87 (44)

Total equilin

2.9 (42)

6.8 (49)

12.5 (34)

48 (51)

Distribution
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.

Metabolism
Metabolic conversion of estrogens occurs primarily in the liver (first pass effect), but also at local target tissue sites. Complex metabolic processes result in a dynamic equilibrium of circulating conjugated and unconjugated estrogenic forms which are continually interconverted, especially between estrone and estradiol and between esterified and non-esterified forms.

When given orally, naturally-occurring estrogens and their esters are extensively metabolized (first pass effect) and circulate primarily as estrone sulfate, with smaller amounts of other conjugated and unconjugated estrogenic species. This results in limited oral potency. By contrast, synthetic estrogens, such as ethinyl estradiol and the nonsteroidal estrogens, are degraded very slowly in the liver and other tissues, which results in their high intrinsic potency.

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.

Excretion
During this enterohepatic recirculation, estrogens are desulfated and resulfated and undergo degradation through conversion to less active estrogens (estriol and other estrogens), oxidation to nonestrogenic substances (catecholestrogens, which interact with catecholamine metabolism, especially in the central nervous system), and conjugation with glucuronic acids (which are then rapidly excreted in the urine).

Estradiol, estrone, and estriol are excreted in the urine, along with glucuronide and sulfate conjugates.

Special Populations and Conditions

No pharmacokinetic studies were conducted in special populations, including patients with renal or hepatic impairment.

Storage And Stability

Store at 15◦C - 30◦C.
Keep out of reach of children.

Special Handling Instructions

None required.

Dosage Forms, Composition And Packaging

PREMARIN (conjugated estrogens sustained release tablets) for oral administration contains a mixture of conjugated estrogens obtained exclusively from natural sources, occurring as the sodium salts of water-soluble estrogen sulfates blended to represent the average composition of material derived from pregnant mares’ urine. It is a mixture of sodium estrone sulphate and sodium equilin sulphate. It contains concomitant components, as sodium sulphate conjugates, 17β-dihydroequilin, 17β-estradiol, and 17α-dihydroequilin. Tablets for oral administration are available in 0.3 mg, 0.625 mg, and 1.25 mg strengths of conjugated estrogens.

PREMARIN 0.3 mg, 0.625 mg, and 1.25 mg tablets also contain the following non-medicinal ingredients: calcium phosphate tribasic, carnauba wax, hydroxypropyl cellulose, hypromellose, lactose monohydrate, magnesium stearate, microcrystalline cellulose, polyethylene glycol, sucrose, purified Water.

PREMARIN Tablets are available as :

0.3 mg (green) tablets in blister strips of 28;

0.625 mg (maroon) tablets in blister strips of 28;

1.25 mg (yellow) tablets in blister strips of 14.

The tablets come in different strengths and each strength tablet is a different color. The color ingredients are:

- 0.3 mg (green color tablet with “0.3” printed in white ink): hypromellose, quinoline yellow lake, macrogol, FD&C Blue No. 2, Indigo carmine aluminum lake, titanium dioxide, polysorbate 80. The white branding ink contains the following: titanium dioxide, purified water, isopropyl alcohol, propylene glycol, hypomellose.

- 0.625 mg (maroon color tablet with “0.625” printed in white ink): hypromellose, titanium dioxide, FD&C Red #40 aluminum lake, macrogol, FD&C Blue #2 aluminum lake. The white branding ink contains the following: titanium dioxide, purified water, isopropyl alcohol, propylene glycol, hypomellose

- 1.25 mg (yellow color tablet with “1.25” printed in black ink): hypromellose, titanium dioxide, quinoline yellow aluminum lake, macrogol, polysorbate, FD&C yellow #6 sunset yellow FCF aluminum lake. The black branding ink contains the following: purified water, iron oxide black, isopropyl alcohol, propylene glycol, hypromellose.

 

Control #: 177429
December 1, 2014

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