What is the equivalent dose of Estrogel (estradiol) for a postmenopausal woman currently using Estradot 25 (estradiol) for menopausal symptoms or osteoporosis prevention?

Estradot 25 to Estrogel Dose Conversion

For a postmenopausal woman currently using Estradot 25 mcg/day (transdermal patch), the equivalent dose of Estrogel is 0.75 mg estradiol gel applied daily, which delivers approximately 25-30 mcg/day of estradiol systemically. 1, 2

Direct Dose Equivalence

Estradot 25 mcg/day patch = Estrogel 0.75 mg (approximately 1.25 grams of 0.06% gel) applied once daily 1, 2

• Both formulations are transdermal 17β-estradiol, avoiding hepatic first-pass metabolism and maintaining physiological estradiol levels 1
• Target serum estradiol levels for symptom control range from 35-55 pg/mL, which both the 25 mcg patch and 0.75 mg gel achieve 3, 2
• The 0.75 mg Estrogel dose was demonstrated in phase 3 trials to significantly reduce moderate to severe hot flushes by 75% and improve vaginal maturation index compared to placebo 2

Bioequivalence Considerations

• Transdermal estradiol patches and gels produce comparable serum concentrations of estradiol and estrone when delivering equivalent daily doses 4
• The 0.75 mg Estrogel formulation maintains steady-state estradiol plasma concentrations between 35-100 pg/mL, similar to the Estradot 25 mcg patch 3, 2
• Both delivery systems bypass hepatic metabolism, resulting in more favorable cardiovascular and thrombotic risk profiles compared to oral estrogen 1

Critical Progestin Requirement

If this patient has an intact uterus, she MUST receive concurrent progestin therapy with either formulation to prevent endometrial cancer 1, 5

• Unopposed estrogen increases endometrial cancer risk 10- to 30-fold after 5 years of use 1
• Recommended progestin: micronized progesterone 200 mg orally at bedtime (preferred for breast safety) OR medroxyprogesterone acetate 2.5 mg daily continuous or 10 mg for 12-14 days per month 1
• Women who have had a hysterectomy can use estrogen-alone therapy safely 1, 5

Practical Switching Instructions

• Apply Estrogel 0.75 mg (one pump actuation or 1.25 grams of 0.06% gel) once daily to clean, dry skin on the arm or thigh 2
• Remove the final Estradot patch and begin Estrogel the following day—no washout period is needed 1
• Allow gel to dry for 2-5 minutes before dressing; avoid washing the application site for at least 1 hour 2
• Rotate application sites to minimize skin irritation 2

Monitoring and Reassessment

• Reassess symptom control at 4-6 weeks after switching formulations 1, 5
• No routine estradiol level monitoring is required—management is symptom-based 1
• Reevaluate necessity of continued therapy every 3-6 months, using the lowest effective dose for the shortest duration consistent with treatment goals 1, 5
• For women over 60 or more than 10 years past menopause, the risk-benefit profile is less favorable, and attempts to discontinue should be made 6, 1

Common Pitfalls to Avoid

• Do not assume the 0.375 mg or 0.27 mg Estrogel doses are equivalent to Estradot 25—these lower doses did not consistently demonstrate efficacy for moderate to severe vasomotor symptoms in clinical trials 2
• Do not prescribe estrogen without progestin in women with an intact uterus—this dramatically increases endometrial cancer risk 1, 5
• Do not continue HRT beyond symptom management needs, as breast cancer risk increases with duration beyond 5 years 6, 1
• Avoid using HRT solely for osteoporosis prevention—bisphosphonates are preferred first-line therapy with superior safety profiles 7