Comparison of transdermal and oral hormone replacement therapy for postmenopausal women

Abstract:

The recent strategy in the prescription of hormone replacement therapy (HRT) follows the application of a minimum dose, thereby reducing the potential side effects and enabling for maximum efficiency and compliance. A transdermal route of administration has been increasing, due to a lower risk of short-term side effects such as vaginal bleeding and breast tension which are attributed to oral therapy. Transfer of bioactive hormones directly into subcutaneous circulation significantly reduces the risk of venous thromboembolism due to avoidance of the oral estrogens’ effect of the first passage through the liver. Skin administration allows for a much smaller portion of estradiol being metabolised to estrone and estrone-sulphate compared to the oral route of administration, thus achieving a circulating estradiol / estrone ratio more similar to the physiological one. In addition, due to the higher bioavailability of transdermal estrogen, lower concentrations are required compared to the oral administration. Therefore, therapeutic circulating levels of estrogen required for vasomotor symptoms are significantly lower when compared to the oral administration.

Key words:
metabolic profile; oral administration; replacement therapy, hormones; thromboembolism; transdermal administration