Estrogen Gel to Patch Conversion
Two pumps of estrogen gel (approximately 1.5-2 mg estradiol) converts to a 100 mcg/24-hour transdermal estradiol patch for equivalent systemic hormone replacement.
Dosing Equivalence
The conversion is based on standard formulation concentrations and delivery rates:
- Estrogen gel: Most commercially available estradiol gels deliver approximately 0.75-1 mg estradiol per pump actuation 1, 2
- Two pumps: This provides approximately 1.5-2 mg total estradiol dose 1
- Patch equivalent: A 100 mcg/24-hour transdermal patch is the appropriate conversion for this gel dose 3, 4
Rationale for Conversion
The 100 mcg/24-hour patch falls within the recommended maintenance dose range of 100-200 mcg/day for adult women requiring hormone replacement therapy 3. This dosing achieves therapeutic estradiol levels while minimizing risks associated with supraphysiologic dosing.
For patients requiring lower doses, a 50 mcg/24-hour patch may be considered if symptoms are adequately controlled, as transdermal delivery at 50-100 μg daily is recommended for initial hormone replacement 4.
Application Guidelines
- Patch frequency: Change patches either twice weekly or weekly depending on the specific brand formulation 3
- Application sites: Apply to clean, dry, intact skin on the lower abdomen, upper buttocks, back, or upper arms 4
- Endometrial protection: If the patient has an intact uterus, add progesterone (200 mg oral or vaginal micronized progesterone daily for 12-14 days every 28 days) for endometrial protection 3
Important Clinical Considerations
Transdermal delivery advantages: The patch formulation avoids first-pass hepatic metabolism, provides more stable hormone levels, and has a lower risk of venous thromboembolism compared to oral administration 4.
Monitoring: Evaluate treatment effect after 3-6 months and conduct annual clinical reviews to assess compliance and side effects 4. No routine laboratory monitoring is required unless specific symptoms develop 4.