Overall, the diffference between estrogen and
progestin potencies had no impact on endometrial cancer incidence.
The revised label states that women who choose to take estrogens or an estrogen and
progestin combination after talking to their physician should have annual breast exams and periodic mammograms based on their age and risk factors.
Natazia is formulated as a four-phase estrogen step-down (from 3 mg to 1 mg),
progestin step-up (from 2 mg to 3 mg) regimen (TABLE).
Hormone replacement therapies using estrogen alone or in combination with sequential
progestin supplementation may put women at significantly increased risk of epithelial ovarian cancer, reported Dr.
Grapefruit juice decreases the activity of the enzyme CYP3A4, thus reducing degradation and increasing the concentrations of
progestins and ethinyl estradiol.
Some birth control pills, called mini-pills,contain only
progestin. These pills do not always suppress ovulation, but they make the cervical mucus thick and inhospitable to sperm, preventing entry to the uterus.
A more important unresolved question involves the effect of
progestins on cardiovascular risk.
Interestingly, some studies of the Norplant System suggested small, potential improvement of breakthrough bleeding after treatment with
progestin; however, these effects were weaker than those seen with use of nonsteroidal anti-inflammatory drugs (NSAIDs).
Because of their ability to inhibit bleeding,
progestins are used to manage excessive or abnormal uterine bleeding (AUB).
The side effects that women list as most troublesome are those associated with the
progestin component in combination regimens.
These results implicate
progestins in the pathogenesis of breast cancer and heart disease in postmenopausal women who take estrogen.
Natural progesterone (non-micronized) is not effective orally and natural progesterone used in over-the-counter creams are not as effective as
progestins or micronized progesterone.
In this study from France, the association between estrogen-progestin regimens and breast cancer varied significantly, depending on the
progestin. The relative risk of invasive breast cancer was 1.08 for progesterone (95% confidence interval 0.89-1.31), 1.16 for dydrogesterone (0.94-1.43), and 1.69 for other
progestins (1.50-1.91).
Endrikat et al (12) conducted a study to compare two 20 [micro]g EE pills containing different
progestins, and to compare 2 levonorgestrel-based formulations with differing EE amounts.
This monograph will describe the uses of progesterone and
progestins in several key areas across a woman's reproductive life.
