The safety of oral versus transdermal estrogen

A phase 1/2, open-label, parallel group study to evaluate the safety and pharmacokinetics of DARE-HRT1 (80 μg estradiol/4 mg progesterone and 160 μg estradiol/8 mg progesterone intravaginal rings) over 12 weeks in healthy postmenopausal women

OBJECTIVES

Primary objectives were to evaluate the safety and systemic pharmacokinetics (PK) of DARE-HRT1, an intravaginal ring (IVR), which releases 17β2-Estradiol (E2) with progesterone (P4) for 28 days in healthy postmenopausal women.

METHODS

This was a randomized, open-label, 2-arm, parallel group study in 21 healthy postmenopausal women with an intact uterus. Women were randomized (1:1) to either DARE-HRT1 IVR1 (E2 80 μg/d with P4 4 mg/d) or DARE-HRT1 IVR2 (E2 160 μg/d with P4 8 mg/d). They used the IVR for three 28-day cycles, inserting a new IVR monthly. Safety was measured by treatment emergent adverse events and changes in systemic laboratories and the endometrial bilayer width. Baseline adjusted plasma PK of E2, P4, and estrone (E1) was described.

RESULTS

Both DARE-HRT1 IVR were safe. All treatment emergent adverse events were mild or moderate and were distributed similarly among IVR1 versus IVR2 users. Month 3 median maximum plasma (Cmax) P4 concentrations were 2.81 and 3.51 ng/mL and Cmax E2 was 42.95 and 77.27 pg/mL for IVR1 and IVR2 groups, respectively. Month 3 median steady state (Css) plasma P4 concentrations were 1.19 and 1.89 ng/mL, and Css E2 was 20.73 and 38.16 pg/mL for IVR1 and IVR2 users, respectively.

CONCLUSIONS

Both DARE-HRT1 IVRs were safe and released E2 in systemic concentrations, which were in the low, normal premenopausal range. Systemic P4 concentrations predict endometrial protection. Data from this study support further development of DARE-HRT1 for the treatment of menopausal symptoms.

Transdermal estrogen therapy in menopausal women at increased risk for thrombotic events: a scoping review

IMPORTANCE AND OBJECTIVE

It is estimated that over 45% of women in the United States are menopausal. Many of these women suffer from vasomotor symptoms of menopause, for which the gold standard treatment is menopause hormone therapy (MHT). However, MHT use has been controversial since the Women's Health Initiative (WHI) study in 2001. Transdermal MHT has been shown to be effective for treatment of vasomotor symptoms and does not increase the risk of venous thromboembolism (VTE) when used in healthy postmenopausal women. However, there is little data on its safety in women at increased risk for VTE such as women with prior VTE, increased body mass index, thrombophilia, tobacco use, autoimmune disease, chronic inflammatory disorders, recent surgery, trauma, or immobilization. This scoping review of the literature provides clinicians with an overview of the evidence on the risk profile of transdermal MHT use in these postmenopausal women at increased risk of VTE.

METHODS

We searched all published studies from 2000 to 2020 and included 13 primary articles on transdermal MHT use in postmenopausal women at increased risk of VTE.

DISCUSSION AND CONCLUSION

In women with prior VTE, two studies found a decrease in coagulability and no increased risk of recurrent VTE with transdermal MHT use. In women with increased body mass index, three studies found no increased VTE risk in transdermal MHT users. In women with prothrombotic genetic polymorphisms, three studies found minimal to no increased VTE risk in transdermal MHT users. In women with various proinflammatory comorbidities, five studies found an improved thrombotic profile and no increased VTE risk with transdermal MHT use. This scoping review provides data regarding the safety of transdermal MHT use in postmenopausal women with risk factors for VTE, and clinicians should have risk versus benefit discussions with each patient regarding its use.