Women who were given a bio-equivalent form of estrogen to relieve menopausal symptoms had fewer blood-clot-related events than those taken estrogen derived from horse urine, a study has shown.
Women can choose among several types of estrogen pills, which are considered equally effective at relieving menopausal symptoms.
But in an observational study of comparative safety, use of estradiol was associated with less risk of developing blood clots in leg veins (deep vein thrombosis) and clots in the lungs (pulmonary emboli) than was use of conjugated equine estrogens.
According to a joint University of Washington study, the findings of which were published in JAMA Internal Medicine, women patients in the study prescribed a generic version of estradiol — a bio-equivalent estrogen — experienced fewer adverse vascular events than did those prescribed conjugated equine estrogens, a patented drug marketed as Premarin.
“Although oral estrogens are effective for managing menopause symptoms, not enough is known about the cardiovascular safety of different oral hormone therapy products relative to each other,” first author Dr Nicholas Smith said.
Smith is a professor of epidemiology at the University of Washington School of Public Health.
To further understand the differences in risk, the researchers also measured clotting factors in the blood of women who did not develop a clot.
The researchers found that, compared with estradiol users, conjugated equine estrogen users had levels of blood factors that made them more prone to form blood clots.
The researchers also investigated other cardiovascular events: The risk of having a heart attack was somewhat — but not significantly — higher in women using oral conjugated equine estrogens than in those using oral estradiol. No difference was seen in the risk of stroke.
“If our results are confirmed,” Smith added, “women seeking menopausal treatment and their providers would find this information helpful when selecting a drug.”
Menopausal symptoms include hot flashes, night sweats, and vaginal dryness, burning, and irritation.
The research, part of a heart and vascular health study, involved 384 people aged 30 to 79, who were taking oral estrogen for menopause symptoms from 2003 to 2009.