Randomised trial, 1995
Is a lower dose of estradiol patch as effective as a higher dose for severe PMS?
Yes. The lower 100 microgram dose was equally effective as 200 micrograms but better tolerated with fewer side effects and less dropout.
What they did
This was an 8-month randomized controlled trial comparing two doses of transdermal estradiol. Women were assigned to either 100 or 200 micrograms of Estraderm TTS (an estradiol skin patch) applied twice weekly continuously, combined with a progestin (either dydrogesterone 10 mg or medroxyprogesterone acetate 5 mg) given from day 17 to day 26 of each cycle.
What they found
Both doses reduced symptoms equally and showed no significant difference in the primary symptom score. The higher dose group had a significantly higher dropout rate and more side effects attributed to estrogen. Satisfaction with treatment was 45% to 57% at 8 months. The 100 microgram dose produced a mean blood estradiol level of 300 pmol/l while the 200 microgram dose produced 573 pmol/l. The 100 microgram dose suppressed midluteal progesterone from a mean of 35.5 to 3.4, confirming it stops ovulation.
What it means for you
Lower-dose estradiol patches are just as effective as higher doses but are better tolerated with fewer dropouts. Both doses suppress ovulation and prevent the hormonal cycle that triggers PMS. However, less than half of women were satisfied, suggesting estradiol works for some but not all.
8 months
Trial duration
45-57%
Satisfaction rate at 8 months
100 or 200 mcg
Estradiol patch doses
About the study
- Original title
- A randomised comparison over 8 months of 100 micrograms and 200 micrograms twice weekly doses of transdermal oestradiol in the treatment of severe premenstrual syndrome
- Authors
- Smith RN, Studd JW, Zamblera D et al.
- Journal
- British journal of obstetrics and gynaecology
- Year
- 1995
- Study design
- Randomised trial
- What was tested
- Estraderm TTS at 100 or 200 micrograms twice weekly, each combined with a progestin
- Read the paper
- doi.org/10.1111/j.1471-0528.1995.tb11321.x
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