[Bioavailability of 17 beta-estradiol after transdermal administration--dependence on the patch system]

Area of Science:

• Endocrinology
• Pharmacology
• Gynecology

Background:

• Postmenopausal hormone therapy aims to alleviate symptoms by restoring hormone levels.
• Transdermal estradiol delivery systems offer an alternative to oral administration, potentially with improved safety profiles.
• Comparing different delivery systems is crucial for optimizing therapeutic outcomes.

Purpose of the Study:

• To compare the pharmacokinetics of serum estradiol concentrations between two transdermal estradiol delivery systems.
• To evaluate estradiol absorption and serum levels over an 80-hour period.
• To assess the suitability of each system for postmenopausal hormone substitution.

Main Methods:

• Prospective randomized crossover study in ten postmenopausal women.
• Application of two transdermal estradiol patches: a reservoir system (4.0 mg E2) and a matrix system (1.8 mg E2).
• Measurement of serum estradiol concentrations over 80 hours with a 7-day washout period.

Main Results:

• The matrix system resulted in significantly higher mean serum estradiol concentrations over 80 hours (p < 0.05).
• Estradiol levels were notably higher with the matrix system at the end of the observation period and after patch removal.
• While fluctuations were greater with the matrix system, areas under the curve were not significantly different.

Conclusions:

• Both transdermal estradiol systems are suitable for postmenopausal hormone substitution, achieving stable serum estradiol levels around 50 pg/ml.
• The matrix system may offer an extended lifespan, potentially allowing for longer application periods.
• Further research could explore the clinical implications of the observed pharmacokinetic differences.