Estrogen in oral contraceptives

Women of reproductive potential prescribed efavirenz should be counseled on its potentially teratogenic effects and the importance of birth control. Additionally, nevirapine, nelfinavir, ritonavir, lopinavir/ritonavir, and tipranavir/ritonavir have been shown to decrease the concentrations of estrogens and/or progestins in oral contraceptives, which could lead to failure.2 For patients prescribed these drugs, barrier forms of contraception are preferred to prevent pregnancy. DepoProvera may be... 

The synthesis of Lp(a) can be influenced by hormones, as is reported by Albers et al. (A7), who observed a reduction of Lp(a) concentrations in nor-molipidemic postmenopausal women treated during 6 weeks with the anabolic steroid stanazolol. The same effect was reported for norethisterone (FI) and danazol (Cl2). Exogenous estrogens, as used in treatment of postmenopausal complaints and in oral contraceptives, induce a decrease of Lp(a) (D9, H27, K13, KAO, L21, S37). This effect is dose-related and dependent on Lp(a) levels before treatment (F2). Watanabe (W9) investigated the influence of progestogen (alone) and detected a decrease of Lp(a) during treatment. 

Contraceptives (oral) and estrogens Ascorbic acid increases serum levels of estrogen and estrogen contained in oral contraceptives, possibly resulting in adverse reactions. 

Synthetic steroid hormones retain the common steroid nucleus, but they may contain novel substituents that affect their pharmacological activity. The two most widely used synthetic steroid estrogens are ethinyl estradiol (Estinyl) and mestranol, found in oral contraceptives. Synthetic steroids containing an ethinyl substitution are metabolized more slowly. Thus, these synthetic steroid hormones have better oral absorption properties and extended biological half-lives than the natural estrogens. 

Mild hypertension and fluid retention frequently occur in oral contraceptive users. Systolic blood pressure is elevated 5 to 6 mm Hg diastolic blood pressure increases are on the order of 1 to 2 mm Hg. Hypertension is not commonly a problem in postmenopausal women receiving conjugated estrogens. 

Today, a variety of therapeutic estrogens are produced semisynthetically from estrogen intermediates synthesized from diosgenin and other natural precursors. Two semisynthetic, orally active estrogens are ethinyl estradiol (5.27) and its 3-methyl ether (5.28, mestranol). Both of these are used in oral contraceptives (see section 5.8.3). Quinestrol (5.29) is another semisynthetic estrogen. The most important property of the semisynthetic estrogens is their increased oral effectiveness. 

Important alterations in hepatic drug excretion and metabolism also occur. Estrogens in the amounts seen during pregnancy or used in oral contraceptive agents delay the clearance of sulfobromophthalein and reduce the flow of bile. The proportion of cholic acid in bile acids is increased while the proportion of chenodeoxycholic acid is decreased. These changes may be responsible for the observed increase in cholelithiasis associated with the use of these agents. 

Ampicillin [NP] Interruption of enterohepatic circulation of estrogen possible reduction in oral contraceptive efficacy. Some other oral antibiotics may have a similar effect. 

Phenytoin [NP] Increased estrogen metabolism possible reduction in oral contraceptive efficacy. 

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