How estradiol works
The hormone estradiol (also called 17-beta-estradiol) is naturally produced in the human body. In women, the largest amount is produced in the ovaries. In men, who have much lower levels of estradiol in their bodies, it is produced in the adrenal cortex and testes.
The term “estrogen” covers the hormones estradiol, estrone and estriol.
Estrogens are not only very important for the formation of female sexual characteristics (such as ovaries, uterus, vagina and breasts), but also for their function.
Menstrual cycle & hormonal fluctuations
The menstrual cycle, which lasts about 28 days, is largely dependent on the changing hormone levels in a woman’s blood:
Ovulation is followed by the luteal phase: The blood levels of estrogen, LH and FSH now decrease, while the concentration of the corpus luteum hormone (progesterone) increases. The corpus luteum is formed from the follicle that remains in the ovary after ovulation. The corpus luteum hormone it produces further prepares the uterine lining for the possible implantation of the fertilized egg.
Estradiol for contraception
By taking estradiol (as the “pill”), the release of FSH is suppressed – ovulation no longer occurs, making fertilization and subsequently pregnancy impossible.
In adaptation to the natural hormonal fluctuations, the “pill” is only taken for 21 days. Then you stop for seven days or take only one tablet without active ingredients.
Estradiol for hormone replacement therapy in menopause
These include mood swings, fatigue, hot flashes, vaginal dryness and bone loss. These symptoms can often be alleviated, if not completely eliminated, with estradiol therapy.
In the past, women were given very large doses of hormones for this purpose, which sometimes led to side effects such as breast cancer and ovarian cancer. In the meantime, lower-dose and thus safer hormone preparations are in use.
Absorption, degradation and excretion
The highest active substance level in the blood is reached after about four to six hours. In the liver, estradiol is then converted into estrone, which is about ten times weaker. It is then excreted mainly via the kidneys (i.e. with the urine).
Do not confuse with 17-alpha-estradiol!
However, it is used locally on the scalp for hair loss caused by excessive levels of DHT (dihydrotestosterone, a substance related to testosterone). Here it inhibits the production of DHT and thus its negative effect on hair growth.
When is estradiol used?
The related active ingredient ethinylestradiol is used far more frequently for contraception, as it has an even more targeted effect and can therefore also be taken in smaller quantities. Very often, combined tablets consisting of an estrogen (ethinylestradiol or estradiol) and a progestogen (for example, norethisterone or drospirenone) are used for contraception, as this makes contraceptive protection even safer.
In addition to tablets, other dosage forms of estradiol are commercially available: transdermal patches for sticking to the skin, vaginal rings, solutions and sprays for application to the skin, and gels for topical use.
How estradiol is used
In hormone replacement therapy, the physician decides whether estradiol should be used continuously or in cycles. In the latter case, there is also a therapy-free week after three weeks of treatment. Other forms of estradiol for hormone replacement therapy are estradiol gel and estradiol patches. The patches usually release the hormone evenly through the skin into the body over a few days. It therefore only needs to be changed every three to four days.
What are the side effects of estradiol?
Estradiol side effects in one in ten to one hundred people treated are headache, depression, abdominal pain, nausea, leg cramps, weight gain, tender chest, or breast pain. In case of occurrence of chest pain, one should inform the doctor – eventually he/she will decrease the dosage.
What should be considered while using estradiol?
Contraindications
Estradiol should not be used in:
- existing or previous breast cancer
- unexplained bleeding in the vaginal area
- previous or existing thrombotic disease (e.g. venous thrombosis)
- genetic or acquired tendency to form thromboses (blood clots)
- recent arterial thromboembolic disease (e.g., myocardial infarction)
- severe liver dysfunction or liver disease
- porphyria (a group of metabolic diseases involving disorders in the formation of the red blood pigment hemoglobin)
Interactions
These include, for example, drugs against convulsions and epilepsy (phenobarbital, phenytoin, carbamazepine), the tuberculosis drug rifampicin, certain drugs against HIV (nevirapine, efavirenz) and the herbal antidepressant St. John’s wort.
Likewise, estradiol use may increase the risk of blood clots forming, which may then clog a vessel (as in pulmonary embolism). This is especially true if a woman smokes or has other risk factors (high cholesterol, obesity, etc.).
Age restriction
Hormone replacement therapies are used in women with declining hormone production after menopause. This is usually in the late forties to fifties.
Pregnancy and breastfeeding
The active substance estradiol should only be used in girls and women from the onset of menstruation, but not in pregnant or breastfeeding women. If pregnancy occurs during treatment, treatment must be stopped immediately and a doctor contacted.
How to get medication with estradiol
Since when has estradiol been known?
Steroid hormones, which include estrogens such as estradiol, but also testosterone and cortisone, were recognized very early as important functional carriers in the body. As early as 1929, the first estrogens were isolated and their structure elucidated by the chemist Adolf Butenandt. In 1939, he was awarded the Nobel Prize in Chemistry together with the steroid researcher Leopold Ruzicka.
Worthwhile chemical manufacturing processes for the active ingredient estradiol were not developed until the second half of the 20th century.
