Synthetic Progestins and Natural Progesterone, A Pharmacist Explores
by Pete Hueseman, RPh, PharmD
brought to you by Bellevue Pharmacy, a ProjectAWARE
We live in an era when more and more emphasis is being placed on
the importance of natural substances. Natural food supplements and
herbal formulations are in demand. Homeopathic physicians and caregivers
are gaining popularity. Everyone seems to be asking, "What
can we do to help the body repair itself in a more natural fashion?"
Many women who take hormone replacement supplements are also asking
the "natural vs. synthetic" question. Is natural always
better? What is the difference between natural micronized progesterone
and the synthetic progestin, medroxyprogesterone, also commonly
prescribed as Provera?
The most outstanding difference...
between the two is that medroxyprogesterone is an analog, a "look
alike", of progesterone, not truly a progesterone at all, but
rather a progestin. The chemical structure of medroxyprogesterone
closely resembles the chemical structure of progesterone as it is
produced naturally in the human body. But, even a slight difference
in the molecular configuration of a compound can produce a totally
different response from its natural counterpart.
Progesterone is the oldest steroid hormonesome 500 million
years old on the evolutionary scale. All vertebrates produce progesterone,
although it is only in higher vertebrates that this hormone is instrumental
in the reproductive cycle. In lower vertebrates progesterone functions
in relation to glucose metabolism, the development of intelligence
and bone formation.
The process of producing natural progesterone, which is made from
yams and soybeans, was discovered by Russell Marker, a Pennsylvania
State College chemistry professor. While experimenting with sapogenins,
a group of plant steroids, in the jungles of Mexico in the 1930s,
Marker realized that progesterone could be transformed by chemical
process from the sapogenin, diosgenin, which is found naturally,
Unlike medroxyprogesterone, natural micronized progesterone is
an exact chemical duplicate of the progesterone that is produced
by the human body.
Another immediate difference...
between medroxyprogesterone and natural progesterone is that the
synthetic hormone can actually lower a patient's blood level of
progesterone. Some women who take medroxyprogesterone to combat
PMS or oppose estrogen in menopause report headaches, mood swings
and fluid retention.
On the other hand, women who take natural micronized progesterone
often say their mood swings diminish. Women who suffer from migraines
as their main complaint with PMS also find that this situation may
be corrected by natural progesterone. In its natural micronized
form, progesterone acts as a diuretic, which means the women who
take these supplements may have to go to the bathroom more frequently,
but they are spared the fluid retention and weight gain experienced
by women on synthetic progestin.
Prescribed dosages also differ in regard to natural and synthetic
progesterone. Synthetic progestin is 10 to 100 times as potent as
the natural progesterone. This appears to be a tremendous range,
but the doses fall well within those limits.
Medroxyprogesterone is sold in 2.5 milligram, 5 milligram and 10
milligram tables. For example, a woman who is using five milligrams
of synthetic progestin would find the corresponding dose of natural
progesterone to be between 50 and 500 milligrams. A dosage of 100
milligrams twice a day or 200 milligrams per day of natural progesterone
will usually produce endometrial conversion or prevent hyperplasia.
Synthetic progestins were developed with the advent of the birth
control pill. The half life of natural progesterone was very short
and researchers were looking for an agent that would give a longer
half life and yet produce or mimic the effects of progesterone.
Birth control pills contain, in most cases, a synthetic progestin
and a synthetic estrogen. The very potent synthetic progestins prevent
ovulation in a very low dose and, therefore, accomplish their function
of birth control.
Conversely, natural progesterone has been use for many years in
pregnancy, luteal phase defect and postpartum depression. When a
woman is pregnant, her progesterone levels are 30 to 50 times higher
than normal. A nursing mother should not be concerned that taking
natural progesterone for postpartum depression will affect the baby.
After all, the baby has been exposed to tremendous levels of progesterone
during its development.
Significant differences exist between
synthetic and natural progesterone. Natural progesterone
duplicates the body's progesterone exactly, causes fewer side effects
and can be more consistently utilized by the body. In the case of
natural progesterone versus synthetic progestins in hormone replacement,
natural does appear to be better.
For questions and further information, contact Bellevue