17-beta Estradiol is the hormone most like the naturally produced estrogen of the ovary, thus making it the hormone of choice for estrogen replacement. The FDA has approved 17-beta Estradiol for use in many commercial preparations. Equally important is how this hormone is delivered to your bloodstream. Once taken, an oral tablet of 17-beta Estradiol is first metabolized in the liver. During which process, unfavorable compounds are created; it is these compounds that impose the vast majority of the risks associated with estrogen replacement. To avoid this first pass though the liver, trans-dermal (topical creams, gels and patches) and sub-dermal (pellet implants) applications are preferred.
There are many FDA approved preparations of bioidentical hormones. Creams, gels, patches and sprays rely on the ability of estrogen to be absorbed quickly through the skin. The rate at which the hormone is absorbed varies from individual to individual. Other local skin factors may influence absorption as well. This may result in suboptimal blood levels and in continued symptoms. Also, some patients may need higher doses than the patch is capable of delivering. That is where compounding pharmacists may be very helpful, provided the prescription is filled ethically and accurately. I have had very good experience with local compounding pharmacists.