Oral Contraceptives and Breast Cancer (1991) / Chapter Skim
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Appendix C: The Evolving Formulations of Oral Contraceptives
Appendix C: The Evolving Formulations of Oral Contraceptives
Pages 143-151
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From page 143... ...
The changing formulations also brought a change in the prescribing preferences and practices of physicians. Today, the most commonly prescribed oral contraceptive for new users in the United States is Ortho 7/7/7, which combines 35 ,ug of ethinyl estradiol with 0.5 to 1 mg of norethindrone (Contraceptive Technology Update, 1989~.
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From page 144... ...
It should be noted, however, that the triphasic formulations containing norethindrone are actually slightly higher in total hormone dose than the two lowest-dose monophasic formulations that contain the same two hormones (Ovcon 35, and Brevicon/Modicon/ Genora 0.5/35; Tables C-1 and C-3~. Over the next five years, a number of new oral contraceptive formulations are likely to become available in the American market.
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From page 145... ...
is 0.5 ma; however, 50 percent is the inactive enantiomer dextronorgestrel. TABLE C-3 Summary of Estrogen and Progestin Contents of Phasic Formulations of Oral Contraceptives Available in the United States Estrogen Progestin Approximate per Total per Total Norethindrone Brand Tableta Estrogen Progestin Tableta Progestin Equivalentsb Name (,ug)
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From page 146... ...
The contraceptive effectiveness of these formulations is high generally less than one pregnancy per 100 woman-years. Cycle control may be slightly better with the gestodene preparation, and slightly poorer with the desogestrel formulation, than is possible with the currently available triphasics TABLE C-4 Summary of Estrogen and Progestin Contents of Potential New U.S.
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From page 147... ...
In both animal and human studies, gestodene has been shown to be the most progestogenic steroid, followed by 3-keto-desogestrel, levonorgestrel, norgestimate, and norethindrone. Many of the unwanted side effects of oral contraceptives relate to the inherent androgenic activity of their components (both through a direct effect and indirectly, by displacing endogenous androgens from SHBG)
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From page 148... ...
There is insufficient clinical experience to confirm or refute these hypotheses. IMPLICATIONS FOR RESEARCH Most of the epidemiological studies to date have provided information exclusively on long-term use of older oral contraceptive formulations that had high total steroid doses.
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From page 149... ...
In addition, although new biological indicators are being studied in an attempt to unravel the etiology of breast cancer, and the potential linkage of oral contraceptive use with breast cancer, pharmacokinetic and pharmacodynamic differences in the way individual women handle steroids should not be overlooked and merit further research. Second, one of the features suggested as a major advantage of the new progestins is that their total steroid content is generally lower than that- of many currently available formulations.
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From page 150... ...
In summary, four questions related to oral contraceptive formulation stand as top research priorities for the 1990s. Do individual variations in blood levels in ethinyl estradiol and the progestin component of oral contraceptives affect risk of breast cancer?
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From page 151... ...
1990. Regulation of progesterone-binding breast cyst protein GCDFP-24 secretion by estrogens and androgens in human breast cancer cells: A new marker of steroid action in breast cancer.
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