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Estring

Clinical Pharmacology
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Clinical Pharmacology

Estring

Endometrial overstimulation, as evaluated in non-hysterectomized patients participating in the U.S. study by the progestogen challenge test and pelvic sonogram, was reported for none of the 58 (0%) patients receiving ESTRING and 4 of the 35 patients (11%) receiving conjugated estrogens vaginal cream.

Of the U.S. women who completed 12 weeks of treatment, 95% rated product comfort for ESTRING as excellent or very good compared with 65% of patients receiving conjugated estrogens vaginal cream, 95% of ESTRING patients judged the product to be very easy or easy to use compared with 88% of cream patients, and 82% gave ESTRING an overall rating of excellent or very good compared with 58% for the cream.

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 either the use of oral conjugated estrogens (CE 0.625 mg) alone per day or in combination with medroxyprogesterone acetate (MPA 2.5 mg) per day compared to placebo in the prevention of certain chronic diseases. The primary endpoint was the incidence of coronary heart disease (CHD) (nonfatal myocardial infarction (MI), silent MI and CHD death), with invasive breast cancer as the primary adverse outcome studied. A “global index” included the earliest occurrence of CHD, invasive breast cancer, stroke, pulmonary embolism (PE), endometrial cancer (only in the CE/MPA substudy), colorectal cancer, hip fracture, or death due to other cause. The study did not evaluate the effects of CE or CE/MPA on menopausal symptoms.

The 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 age 63 years, 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 6.8 years are presented in Table2.

TABLE 2: RELATIVE AND ABSOLUTE RISK SEEN IN THE ESTROGEN ALONE SUBSTUDY OF WHI a

Eventc Relative Riska
CE vs. Placebo
(95% CIa)		 Placebo
n = 5,429		 CE
n = 5,310
Absolute Risk per 10,000 Women-Years
CHD eventsb 0.95 (0.79-1.16) 56 53
  Non-fatal MIb 0.91 (0.73-1.14) 43 40
  CHD deathb 1.01 (0. 71-1.43) 16 16
Strokec 1.39 (1.10-1.77) 32 44
Deep vein trombosisb,d 1.47 (1.06-2.06) 15 23
Pulmonary embolismb 1.37 (0.90-2.07) 10 14
Invasive breast cancerb 0.80 (0.62-1.04) 34 28
Colorectal cancerc 1.08 (0.75-1.55) 16 17
Hip fracturec 0.61 (0.41-0.91) 17 11
Vertebral fracturesc,d 0.62 (0.42-0.93) 17 11
Total fracturesc,d 0.70 (0.63-0.79) 195 139
Death due to other causesc,e 1.08 (0.88-1.32) 50 53
Overall mortalityc,d 1.04 (0.88-1.22) 78 81
Global index b,f 1.01 (0.91-1.12) 190 192
aNominal confidence intervals unadjusted for multiple looks and multiple comparisons.
b Results are based on centrally adjudicated data for an average follow-up of 7.1 years.
c Results are based on an average follow-up of 6.8 years.
d Not included in Global index.
e All deaths, except from breast or colorectal cancer, definite/probable CHD, PE or cerebrovascular disease.
f A subset of the events was combined in a “global index” defined as the earliest occurrence of CHD events, invasive breast cancer, stroke, pulmonary embolism, colorectal cancer, hip fracture, or death due to other causes.

Brand Name: Estring
Generic Name: Estradiol Vaginal Ring
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