Estriol

What is estriol?

Estriol is a steroid hormone that is the main estrogen in pregnant women, and is only present at very low levels in non-pregnant women. It has historically been considered a much weaker estrogen than estradiol (R).

Is estriol stable?

Formulations containing 2% estriol in addition to 1% estradiol, 1% estrone, 20% progesterone and 5% testosterone have been demonstrated to remain stable when incorporated in 3 different cream bases and refrigerated or stored at room temperature for 6 months (R).

Does estriol get absorbed?

Estriol penetrates the skin more slowly and to a smaller extent than estradiol, estrone and progesterone (R, R, R). In an experiment on mouse skin, less than 3% of the applied estriol had penetrated the skin after 16 hours, compmared to 18% for estradiol and 11% for estrone (R). Moreover, only low concentrations of estriol reaches the dermis of human skin (R).

What happens after estriol is absorbed?

Unlike estrone and estradiol, only a small amount of the absorbed estriol is metabolised in mouse skin (R).