Delivery systems for hormone replacement therapy

The steroid hormones used for hormone replacement therapy in the menopausal transition and postmenopause can be administered by several different routes using a variety of delivery systems. The conventional approach to administration has been oral, and this is still the standard against which other routes are compared. However, there is a steadily increasing research development and popularity for alternative systems. Such systems can be geared to ultra low-dose delivery for local vaginal effect or higher dosages for systemic effect. Different delivery systems have a range of attributes with varying appeal to different individual women. Such a range of choices can be important for acceptability and compliance. One of the most important attributes of many newer delivery systems is the potential to deliver hormones in a controlled manner over prolonged periods of time, allowing constant low dosages, as well as constant blood and tissue levels. They also have the potential for reducing side effects and metabolic effects. Transdermal, subdermal, intravaginal and intrauterine systems are particularly likely to undergo refinement and further development in the foreseeable future with subsequent increases in popularity.