Comparative bioequivalence studies with Estradot and Menorest transdermal systems

Area of Science:

• Endocrinology
• Dermatology
• Pharmacokinetics

Background:

• Menopause is associated with declining estrogen levels, necessitating hormone replacement therapy.
• Transdermal estradiol systems (ETS) offer a continuous delivery of estradiol for managing menopausal symptoms.
• Estradot is a novel, small-size estradiol transdermal system designed for improved patient compliance and efficacy.

Purpose of the Study:

• To evaluate the relative bioavailability of Estradot compared to Menorest in healthy postmenopausal women.
• To assess the pharmacokinetic profiles of estradiol and estrone following transdermal application of both systems.
• To compare the local skin tolerability of Estradot and Menorest.

Main Methods:

• Two open-label, randomized, crossover bioequivalence studies were conducted in healthy postmenopausal women (aged 40-65 years).
• Study 1 involved single-dose application of Estradot (5 cm(2) and 10 cm(2)) and Menorest (29 cm(2)) for 84 hours.
• Study 2 utilized multiple-dose application of Estradot (5 cm(2)) and Menorest (14.5 cm(2)) over four consecutive treatments, with blood sampling for estradiol and estrone level determination.

Main Results:

• Estradot demonstrated comparable C(max) values for estradiol and estrone to Menorest in both single-dose and multiple-dose studies.
• Mean maximum serum concentrations (C(max)) for estradiol were 56.7 pg/ml for Estradot and 52.7 pg/ml for Menorest in the multiple-dose study.
• While both systems showed minimal skin irritation, Estradot resulted in significantly less erythema and edema compared to Menorest.

Conclusions:

• Estradot is bioequivalent to Menorest in terms of achieving comparable serum estradiol and estrone concentrations.
• The novel Estradot system offers a favorable safety profile with reduced skin irritation.
• Estradot represents a viable and potentially improved therapeutic option for hormone replacement therapy in postmenopausal women.