Transitioning from Oral Estrogen to Transdermal Estrogen Patch

Dosing Recommendations

The recommended approach for switching from oral estrogen to a transdermal estrogen patch is to discontinue oral estrogen and immediately start with a transdermal patch delivering 50-100 μg of 17β-estradiol daily, applied to dry, intact skin, which provides physiological estrogen levels while avoiding first-pass hepatic metabolism, as per the guidelines from Blood Reviews 1
Peak estradiol levels occur approximately 6-8 hours after patch application, according to Praxis Medical Insights 2

Apply to clean, dry, intact skin on the lower abdomen, upper buttocks, back, or upper arms, as recommended by Praxis Medical Insights 2
Avoid areas with excessive hair, oily skin, irritation, or that are subject to friction from clothing, as advised by Praxis Medical Insights 2

Transdermal delivery avoids first-pass hepatic metabolism, allowing for lower doses while maintaining therapeutic levels, and provides more stable hormone levels compared to oral administration, as noted by Praxis Medical Insights 2
Transdermal estrogen is associated with a lower risk of venous thromboembolism compared to oral estrogen, according to the Annals of Internal Medicine 3
Transdermal estrogen may have less negative impact on lipid metabolism, as reported by Blood Reviews 1

For women with an intact uterus, progestogen must be added for endometrial protection, with first choice being Micronized progesterone 200 mg daily for 12-14 days per month, as recommended by Blood Reviews and Praxis Medical Insights 1, 4
Alternative options include Medroxyprogesterone acetate 10 mg daily or dydrogesterone 10 mg daily for 12-14 days per month, according to Blood Reviews and Praxis Medical Insights 1, 4

Evaluate treatment effect after 3-6 months, as suggested by Praxis Medical Insights 2
Annual clinical review is recommended, with particular attention to compliance, as advised by Human Reproduction Update 5
No routine laboratory monitoring is required but may be prompted by specific symptoms or concerns, according to Human Reproduction Update and Praxis Medical Insights 5, 4

For women with contraindications to transdermal delivery, oral 17β-estradiol can be considered as an alternative, as reported by Blood Reviews 1
Transdermal estrogen patches may worsen urinary incontinence in some women, according to the Annals of Internal Medicine 3

Ethinyl estradiol should not be used for HRT; HRT should use bioidentical 17β-estradiol instead 6, 7
If transdermal delivery is contraindicated, oral 17β-estradiol 1 mg daily can be considered as second-line therapy 7
Vaginal 17β-estradiol is not appropriate for systemic HRT, only for local genitourinary symptoms 8