Levonorgestrel (LNG) is a synthetic progestational hormone with actions similar to those of progesterone and about twice as potent as its racemic or (+-)-isomer (norgestrel). It is used for contraception, control of menstrual disorders, and treatment of endometriosis. It is usually supplied in a racemic mixture (Norgestrel, 6533-00-2). Only the levonorgestrel isomer is active. Within an Intrauterine device (IUD), sold as Mirena among others, it is effective for long term prevention of pregnancy. The local mechanism by which continuously released LNG enhances contraceptive effectiveness of Mirena has not been conclusively demonstrated. Studies of Mirena and similar LNG IUS prototypes have suggested several mechanisms that prevent pregnancy: thickening of cervical mucus preventing passage of sperm into the uterus, inhibition of sperm capacitation or survival, and alteration of the endometrium. Mirena has mainly local progestogenic effects in the uterine cavity. The high local levels of levonorgestrel lead to morphological changes including stromal pseudodecidualization, glandular atrophy, a leukocytic infiltration and a decrease in glandular and stromal mitoses. Ovulation is inhibited in some women using Mirena. In a 1-year study, approximately 45% of menstrual cycles were ovulatory, and in another study after 4 years, 75% of cycles were ovulatory. There has been much debate regarding levonorgestrel emergency contraception's (LNG-EC's) method of action since 1999 when the Food and Drug Administration first approved its use. Proponents of LNG-EC have argued that they have moral certitude that LNG-EC works via a non-abortifacient mechanism of action, and claim that all the major scientific and medical data consistently support this hypothesis. However, newer medical data serve to undermine the consistency of the non-abortifacient hypothesis and instead support the hypothesis that preovulatory administration of LNG-EC has significant potential to work via abortion. The implications of the newer data have important ramifications for medical personnel, patients, and both Catholic and non-Catholic emergency room protocols. In the future, technology such as the use of early pregnancy factor may have the potential to quantify how frequently preovulatory LNG-EC works via abortion. The latest scientific and medical evidence now demonstrates that levonorgestrel emergency contraception theoretically works via abortion quite often. The implications of the newer data have important ramifications for medical personnel, patients, and both Catholic and non-Catholic emergency room rape protocols.

Diethylstilbestrol is a synthetic non-steroidal estrogen. It is used in the treatment of menopausal and postmenopausal disorders, prostate cancer and in the prevention of miscarriage or premature delivery in pregnant women prone to miscarriage or premature delivery. Diethylstilbestrol is a very potent full agonist of the estrogen receptors. At the cellular level, estrogens increase the synthesis of DNA, RNA, and various proteins in target tissues. Pituitary mass is also increased. Estrogens reduce the release of gonadotropin-releasing hormone from the hypothalamus, leading to a reduction in release of follicle-stimulating hormone and luteinizing hormone from the pituitary. Adverse effects are: breast pain or tenderness, enlargement of breasts, gynecomastia, peripheral edema and others. Estrogens may interfere with the effects of bromocriptine. Dosage adjustment may be needed. Concurrent use with estrogens may alter the metabolism and protein binding of the glucocorticoids, leading to decreased clearance, increased elimination half-life, and increased therapeutic and toxic effects of the glucocorticoids.

Levormeloxifene (INN) is an experimental selective estrogen receptor modulator (SERM) that was being developed as an alternative to estrogen replacement therapy for the treatment and prevention of postmenopausal bone loss. Levormeloxifene is the levorotatory enantiomer of non-hormonal, non-steroidal oral contraceptive -- ormeloxifene (trade names Novex-DS, Centron, and Sevista). The development of Levormeloxifene was stopped because of a high incidence of gynecologic adverse events during clinical trials.

Nomegestrol acetate (NOMAC) is a 19-norprogesterone derivative with high biological activity at the progesterone receptor, a weak anti-androgenic effect, but with no binding to estrogen, glucocorticoid or mineralocorticoid receptors. Nomegestrol has been developed by the Monaco-based company Théramex SAM (a Teva subsidiary). Nomegestrol acetate has been used successfully for the treatment of some gynaecological disorders (menstrual disturbances, dysmenorrhoea, premenstrual syndrome) and as a component of hormone replacement therapy in combination with estradiol for the relief of menopausal symptoms; it has been approved in Europe as monotherapy for the treatment of the menopausal syndrome, uterine diseases and menorrhagia, and in combination with an estrogen for the treatment of menopausal symptoms. Nomegestrol acetate in combination with estradiol is used as an oral contraceptive.