Progesterone is a natural hormone produced by the ovary during the second
half of the menstrual cycle.
It provides natures way to change the lining of the uterus so that the cells
which line the uterus can provide nutrition to the developing embryo during
the earliest phases of development after conception.
If conception fails to occur, then lower levels of progesterone and estrogen
in the blood leads to menstruation which is a shedding of the lining of the
uterus. This natural periodic shedding is an important prevention of the
development of uterine cancer.
Women lacking adaquate progesterone and who produce or are exposed to persistent
levels of estrogen are at greater risk for this form of cancer.
Other benefits of progesterone include assisting in the final development
of the female breast during puberty.
As progesterone has a mild sedative effect, many clinicians feel Premenstrual
Syndrome (PMS) is related to progesterone but not well understood.
Side effects when progesterone is administered may include fluid retention,
irritability, depression, and hypoglycemia attacks.
The two general forms of progesterone available pharmacologically in the
United States are progesterone and progestins. Progesterone has 21 carbon
Progestogins are derived from a powerful male hormone, testosterone, which
has 19 carbon atoms. Their chemical structures are very similar.
There were two reasons why it was necessary to develop these synthetic
1. Progesterone has unpredictable adsorption except when micronized for oral
use or made into vaginal suppositories.
2. There are good natural sources for the progesterone molecule from the
same molecules used to manufacture progestogins which is found in many plant
sources such as Mexican sweet potatoes.
The progestogens most commonly used for menopause management is
Medroxyprogesterone acetate (Provera, Amen, Cycrin) which comes in 2.5 mg,
5.0 mg, and 10.0 mg tablets.
Unfortunately, many women have side effects to this preparation, particularly
the 10mg dose.
There are other progestogens including:
Norethindrone acetate (Aygestin) 5 mg (which is a bit too potent for most
Norethindrone (NorQD, Micronor) 0.35 mg and dl-Norgestrel (Ovrette) 0.075
mg are birth control pills and potent enough to reverse the effects of estrogen
on the uterus when given 2 or 3 tablets daily.
Megestrol acetate (Megace ) 20 mg, 40 mg is also a progestogen used in the
treatment of cancer and endometriosis with dosages of 20-40 mg daily which
is potent enough for menopause management.
Other forms of progesterone include micronized progesterone capsules and
vaginal suppositories (manufactured by pharmacists) in 25 mg, 50 mg, 100
mg, 200 mg, and progesterone in oil injection 50 mg/ml, and
Ingestible progesterones are not appropriate for menopause management.