WARNINGS
Included as part of the PRECAUTIONS section.
PRECAUTIONS
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 or family
history of VTE, obesity, and systemic lupus erythematosus) should be managed
appropriately.
Stroke
In the WHI estrogen-alone substudy, 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 [see Clinical Studies]. 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).1
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) [see
Clinical Studies]. The increase in risk was demonstrated after the first
year and persisted.1 Should a stroke occur or be suspected, estrogen
plus progestin therapy should be discontinued immediately.
Coronary Heart Disease
In the WHI estrogen-alone substudy, no overall effect on
coronary heart disease (CHD) events (defined as nonfatal MI, silent MI, or CHD
death) was reported in women receiving estrogen-alone compared to placebo2
[see Clinical Studies].
Subgroup analyses of women 50 to 59 years of age suggest
a statistically non-significant reduction in CHD events (CE [0.625 mg]-alone
compared to placebo) in women with less than 10 years since menopause (8 versus
16 per 10,000 women-years).1
In the WHI estrogen plus progestin substudy, there was a
statistically non-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).1 An increase in
relative risk was demonstrated in year 1, and a trend toward decreasing
relative risk was reported in years 2 through 5 [see Clinical Studies].
In postmenopausal women with documented heart disease (n
= 2,763, average 66.7 years of age), in a controlled clinical trial of
secondary prevention of cardiovascular disease (Heart and Estrogen/Progestin
Replacement Study; HERS), treatment with daily CE (0.625 mg) plus 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 CHD. There were more CHD events in the
CE plus MPA-treated group than in the placebo group in year 1, 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 (0.625 mg) plus MPA (2.5 mg) group and the placebo group in HERS,
HERS II, and overall.
Venous Thromboembolism (VTE)
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
years3 [see Clinical Studies]. 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 persisted4 [see
Clinical Studies]. Should a VTE occur or be suspected, estrogen plus
progestin therapy should be discontinued immediately.
If feasible, estrogens should be discontinued at least 4
to 6 weeks before surgery of the type associated with an increased risk of
thromboembolism, or during periods of prolonged immobilization.
Malignant Neoplasms
Endometrial Cancer
An increased risk of endometrial cancer has been reported
with the use of unopposed estrogen therapy in a woman 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 estrogens 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.
Clinical surveillance of all women using estrogen-alone
or estrogen plus progestin therapy is important. Adequate diagnostic measures,
including directed or random endometrial sampling when indicated, should be
undertaken to rule out malignancy in postmenopausal women with undiagnosed persistent
or recurring abnormal genital 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.
Breast Cancer
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 (RR) 0.80]5 [see
Clinical Studies].
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.6 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 [see Clinical Studies].
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.
Ovarian Cancer
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.7
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 0.83-2.66). The absolute risk of probable
dementia for CE-alone versus placebo was 37 versus 25 cases per 10,000
women-years8 [see Use in Specific Populations, and Clinical
Studies].
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
1.21-3.48). The absolute risk of probable dementia for CE plus MPA versus
placebo was 45 versus 22 cases per 10,000 women-years8 [see Use
in Specific Populations, and Clinical Studies].
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 1.19-2.60). Since both ancillary studies were
conducted in women 65 to 79 years of age, it is unknown whether these findings
apply to younger postmenopausal women8 [see Use in Specific
Populations, and Clinical Studies].
Gallbladder Disease
A 2-to 4-fold increase in the risk of gallbladder disease
requiring surgery in postmenopausal women receiving 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 estrogens. 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, estrogens should be permanently discontinued.
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.
Addition Of A Progestin When A Woman Has Not Had A Hysterectomy
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 that may be associated
with the use of progestins with estrogens compared to estrogen-alone regimens.
These include an increased risk of breast cancer.
Elevated Blood Pressure
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.
Hypertriglyceridemia
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.
Hepatic Impairment And/Or Past History Of Cholestatic
Jaundice
Estrogens may be poorly metabolized in patients 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.
Hypothyroidism
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
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.
Fluid Retention
Estrogens may cause some degree of fluid retention. Women
with conditions that might be influenced by this factor, such as cardiac or
renal dysfunction, warrant careful observation when estrogen alone is
prescribed.
Hypocalcemia
Estrogen therapy should be used with caution in
individuals with hypoparathyroidism as estrogen-induced hypocalcemia may occur.
Hereditary Angioedema
Exogenous estrogens may exacerbate symptoms of angioedema
in women with hereditary angioedema.
Exacerbation Of Endometriosis
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.
Exacerbation Of Other Conditions
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.
Laboratory Tests
Serum follicle stimulating hormone (FSH) and estradiol
levels have not been shown to be useful in the management of moderate to severe
vasomotor symptoms and moderate to severe symptoms of vulvar and vaginal
atrophy.
Laboratory parameters may be useful in guiding dosage for
the treatment of hypoestrogenism due to hypogonadism, castration and primary
ovarian failure.
Drug-Laboratory Test Interactions
Accelerated prothrombin time, partial thromboplastin
time, and platelet aggregation time; increased platelet count; increased
factors II, VII antigen, VIII antigen, VIII coagulant activity, IX, X, XII,
VII-X complex, II-VII-X complex, and beta-thromboglobulin; decreased levels of
antifactor Xa and antithrombin III, decreased antithrombin III activity;
increased levels of fibrinogen and fibrinogen activity; increased plasminogen
antigen and activity.
Increased thyroid-binding globulin (TBG) levels leading
to increased circulating total thyroid hormone levels as measured by
protein-bound iodine (PBI), T4 levels (by column or by radioimmunoassay) or T3 levels
by radioimmunoassay. T3 resin uptake is decreased, reflecting the elevated TBG.
Free T4 and free T3 concentrations are unaltered. Women on thyroid replacement
therapy may require higher doses of thyroid hormone.
Other binding proteins may be elevated in serum, for
example, corticosteroid binding globulin (CBG), sex hormone-binding globulin (SHBG),
leading to increased total circulating corticosteroids and sex steroids,
respectively. Free hormone concentrations, such as testosterone and estradiol,
may be decreased. Other plasma proteins may be increased (angiotensinogen/renin
substrate, alpha-1-antitrypsin, ceruloplasmin).
Increased plasma high-density lipoprotein (HDL) and HDL2 cholesterol
subfraction concentrations, reduced low-density lipoprotein (LDL) cholesterol
concentrations, increased triglyceride levels.
Impaired glucose tolerance.
Patient Counseling Information
See FDA-approved patient
labeling (PATIENT INFORMATION).
Vaginal Bleeding
Inform postmenopausal women of
the importance of reporting vaginal bleeding to their healthcare provider as
soon as possible [see WARNINGS AND PRECAUTIONS].
Possible Serious Adverse
Reactions With Estrogens
Inform postmenopausal women of
possible serious adverse reactions of estrogen therapy including Cardiovascular
Disorders, Malignant Neoplasms, and Probable Dementia [see WARNINGS
AND PRECAUTIONS].
Possible Less Serious But
Common Adverse Reactions With Estrogens
Inform postmenopausal women of
possible less serious but common adverse reactions of estrogen therapy such as
headache, breast pain and tenderness, nausea and vomiting.
Nonclinical Toxicology
Carcinogenesis, Mutagenesis, Impairment Of Fertility
Long-term continuous administration of natural and
synthetic estrogens in certain animal species increases the frequency of
carcinomas of the breast, uterus, cervix, vagina, testis, and liver.
Use In Specific Populations
Pregnancy
PREMARIN should not be used during pregnancy [see CONTRAINDICATIONS].
There appears to be little or no increased risk of birth defects in children
born to women who have used estrogens and progestins as an oral contraceptive
inadvertently during early pregnancy.
Nursing Mothers
PREMARIN 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 mothers receiving estrogen-alone therapy.
Caution should be exercised when PREMARIN 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 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.
Geriatric 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.
The Women's Health Initiative Study
In the WHI estrogen-alone substudy (daily CE 0.625
mg-alone versus placebo), there was a higher relative risk of stroke in women
greater than 65 years of age [see Clinical Studies].
In the WHI estrogen plus progestin substudy (daily CE
[0.625 mg] plus MPA [2.5 mg]), there was a higher relative risk of nonfatal
stroke and invasive breast cancer in women greater than 65 years of age [see
Clinical Studies].
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 [see WARNINGS AND PRECAUTIONS, and Clinical Studies].
Since both ancillary studies were conducted in women 65
to 79 years of age, it is unknown whether these findings apply to younger
postmenopausal women8 [see WARNINGS AND PRECAUTIONS, and Clinical
Studies].
Renal Impairment
The effect of renal impairment on the pharmacokinetics of
PREMARIN has not been studied.
Hepatic Impairment
The effect of hepatic impairment on the pharmacokinetics
of PREMARIN has not been studied.
REFERENCES
1. Rossouw JE, et al. Postmenopausal Hormone Therapy and
Risk of Cardiovascular Disease by Age and Years Since Menopause. JAMA.
2007;297:1465-1477.
2. Hsia J, et al. Conjugated Equine Estrogens and
Coronary Heart Disease. Arch Int Med. 2006;166:357-365.
3. Curb JD, et al. Venous Thrombosis and Conjugated
Equine Estrogen in Women Without a Uterus. Arch Int Med. 2006;166:772-780.
4. Cushman M, et al. Estrogen Plus Progestin and Risk of
Venous Thrombosis. JAMA. 2004;292:1573-1580.
5. Stefanick ML, et al. Effects of Conjugated Equine
Estrogens on Breast Cancer and Mammography Screening in Postmenopausal Women
With Hysterectomy. JAMA. 2006;295:1647-1657.
6. Chlebowski RT, et al. Influence of Estrogen Plus
Progestin on Breast Cancer and Mammography in Healthy Postmenopausal Women. JAMA.
2003;289:3234-3253.
7. Anderson GL, et al. Effects of Estrogen Plus Progestin
on Gynecologic Cancers and Associated Diagnostic Procedures. JAMA.
2003;290:1739-1748.
8. Shumaker SA, et al. Conjugated Equine Estrogens and
Incidence of Probable Dementia and Mild Cognitive Impairment in Postmenopausal
Women. JAMA. 2004;291:29472958.