What are the risks of switching from Climara (estradiol) patch to oral estrogen therapy?

From the Guidelines

Switching from Climara patch to oral estrogen may increase the risk of venous embolism by 74% and should be done with caution, considering the potential benefits and risks, particularly in postmenopausal women who are less than 10 years post-menopause, where oral estrogen or estrogen plus progestin can reduce the risk of coronary heart disease by 24% and all-cause mortality by 30%. When considering this switch, it's essential to weigh the potential benefits against the risks, as noted in the study published in the Proceedings of the Nutrition Society 1. The main concerns with oral estrogen include a higher risk of blood clots and a greater impact on liver function compared to transdermal estrogen. The dosage adjustment is crucial since oral estrogen typically requires higher doses to achieve the same blood levels as transdermal estrogen, with common oral options including estradiol (Estrace), conjugated estrogens (Premarin), or estradiol valerate. Key points to consider when switching from Climara patch to oral estrogen include:

• Increased risk of venous embolism
• Potential reduction in coronary heart disease and all-cause mortality in postmenopausal women less than 10 years post-menopause
• Need for dosage adjustment due to differences in bioavailability between oral and transdermal estrogen
• Importance of medical supervision and hormone level monitoring during the transition
• Possible differences in side effects, such as nausea, headaches, or breast tenderness, due to the first-pass metabolism of oral estrogen. As highlighted in the Journal of the National Comprehensive Cancer Network 1, the choice between oral and transdermal estrogen should be individualized, considering the patient's specific risks and benefits, and alternatives to hormone therapy should be explored first.

From the FDA Drug Label

The Women’s Health Initiative (WHI) study reported increased risks of myocardial infarction, stroke, invasive breast cancer, pulmonary emboli, and deep vein thrombosis in postmenopausal women (50 to 79 years of age) during 5 years of treatment with oral conjugated estrogens (CE 0.625 mg) combined with medroxyprogesterone acetate (MPA 2. 5 mg) relative to placebo. Estrogens with or without progestins should be prescribed at the lowest effective doses and for the shortest duration consistent with treatment goals and risks for the individual woman.

There is no direct information in the provided drug labels about the specific harm of switching from Climara patch to oral estrogen. Key points:

• The labels discuss the risks associated with estrogen therapy, including cardiovascular and malignant neoplasms risks.
• They do not provide information on the safety of switching from a transdermal patch to oral estrogen.
• The decision to switch should be made on a case-by-case basis, considering the individual woman's treatment goals and risks 2, 2.

From the Research

Switching from Climara Patch to Oral Estrogen

• The Climara patch is a transdermal estradiol system used for estrogen replacement therapy 3.
• Switching from the Climara patch to oral estrogen may have different effects on the body, as oral estrogens are biologically transformed by first-pass metabolism in the liver, whereas transdermal preparations avoid first-pass metabolism 4.
• A study comparing oral versus transdermal estrogen replacement therapy found that transdermal ERT significantly reduced factor VII activity, while oral ERT had no effect, but oral ERT significantly reduced PAI 1 concentration, suggesting an improved fibrinolytic capacity 5.
• Another study found that oral conjugated equine estrogens (CEEs) use was associated with a higher risk of incident venous thrombosis and possibly myocardial infarction than oral estradiol use 6.
• The type of hormone used, as well as the route of administration, may affect the vascular benefits of hormone replacement therapy, with transdermal preparations potentially providing more benefits than oral estrogens 4.

Potential Risks and Benefits

• The risk of cardiovascular events may be lower with oral estradiol compared to oral conjugated equine estrogens 6.
• Transdermal estrogen replacement therapy, such as the Climara patch, may have a more favorable effect on blood coagulation and fibrinolysis compared to oral estrogen therapy 5.
• The choice of hormone replacement therapy should be individualized, taking into account the woman's age, cardiovascular condition, and other factors, to minimize risks and maximize benefits 4.