Daily Estradiol Delivery from 50 µg Transdermal Patch
A 50 µg transdermal estradiol patch delivers 50 micrograms of estradiol per day (50 µg/day). 1, 2
Understanding Patch Nomenclature
The "50 µg" designation on transdermal estradiol patches refers to the daily delivery rate, not the total drug content in the patch. 1, 2, 3
- When a patch is labeled as "50 µg," this means it releases 50 micrograms of estradiol every 24 hours throughout its wearing period 1, 2
- This delivery rate remains constant whether the patch is designed for twice-weekly application (every 3-4 days) or once-weekly application (every 7 days) 1, 4, 5
Application Schedule Does Not Change Daily Delivery
The twice-weekly application schedule does not affect the daily delivery rate:
- Patches releasing 50 µg/day are typically applied twice weekly (every 3-4 days) or once weekly depending on the specific brand formulation 1, 2, 4
- Each patch continuously delivers 50 µg per 24-hour period until it is removed and replaced 6, 5, 7
- The total estradiol delivered over the wearing period equals: 50 µg/day × number of days worn (e.g., 200 µg total over 4 days for twice-weekly patches, or 350 µg total over 7 days for weekly patches) 5, 7
Clinical Context for Postmenopausal Women
For postmenopausal hormone replacement therapy:
- The standard starting dose is a patch delivering 50 µg/24 hours, applied twice weekly 2, 3
- This achieves therapeutic plasma estradiol levels of approximately 38-49 pg/mL at steady state 6, 8, 7
- If symptoms persist after 2-3 months, the dose can be increased to 100 µg/day patches 2, 3
- Women with an intact uterus require progestin supplementation (200 mg micronized progesterone for 12-14 days every 28 days) for endometrial protection 1, 2, 4
Common Pitfall to Avoid
Do not confuse the patch strength designation with weekly or per-application dosing. The "50 µg" always refers to the amount delivered per 24-hour period, not per patch or per week. 1, 2, 7