Estrogen, antagonist

As noted previously, triarylethylenes substituted by a basic group, such as clomiphene, exhibit estrogen antagonist activity. Formal cyclization of that molecule to a more steroid-like, rigid conformation enhances potency in this series. 

Breast cancer is cancer of the breast tissues. The major part of this cancer in women is dependent on the female sex hormones for their growth. An estrogen antagonist can therefore be used in the treatment of breast cancer to limit the growth of the tumor. 

Several Grignard reactions are used on an industrial scale in drug synthesis.95 The syntheses of both tamoxifen and droloxifene, which are estrogen antagonists used in treatment of breast cancer and osteoporosis, respectively, involve Grignard addition... 

The answer is d. (Hardman, pp 1275-1276J Tamoxifen is an estrogen antagonist used in the treatment of breast cancer. Postmenopausal women with metastases to soft tissue and whose tumors contain an estrogen receptor are more likely to respond to this agent Little benefit is derived from tamoxifen if the tumor does not have estrogen receptors. 

Gallagher A, Chambers TJ, Tobias JH (1993) The estrogen antagonist ICI 182,780 reduces cancellous bone volume in female rats. Endocrinology 133 2787-2791... 

In summary, available scientific evidence on the effects of tamoxifen on human bone seems to parallel data collected in animal trials. Tamoxifen, acting as a partial estrogen agonist, seems to have beneficial effects on the preservation of bone mass in postmenopausal women, while in premenopausal women it might act as an estrogen antagonist. An alternative explanation could be that... 

Ke HZ, Simmons HA, Pirie CM, Crawford DT, Thompson DD (1995b) Droloxifene, a new estrogen antagonist/agonist, prevents bone loss in ovariectomized rats. Endocrinology 136 2435-2441... 

In preclinical models, arzoxifene exerts an estrogen agonistic effect on bone and on the lipid profile and an estrogen antagonistic effect in breast and endometrium (Sato et al. 1998 Russo et al. 1990 Ma et al. 1998). Thus, in both the ovariectomized rat and the ovary-intact rat arzoxifene did not stimulate uterine weight gain (Russo et al. 1990). 

This is a third-generation SERM. It binds with high affinity to human estrogen receptors and acts as a tissue-selective estrogen antagonist or agonist. 

Black LJ, Goode RL (1980) Uterine bioassay of tamoxifen, trioxifene and a new estrogen antagonist (LY117018) in rats and mice. Life Sci 26(17) 1453-1458... 

Tamoxifen, a first-generation SERM, is a nonsteroidal triphenylethylene derivate routinely used in clinical practice for the treatment and prevention of breast cancer in high-risk populations (Robertson 2004). This drug produces an estrogen antagonist effect on the breast and an estrogen agonist effect... 

Raloxifene hydrochloride is a synthetic nonsteroidal drug derived from the benzothiophene and afferent to SERMs. It is known that raloxifene acts on metabolism, the skeleton, and the cardiovascular system as an estrogenic agonist (Khovidhunkit et al. 1999 Ettinger et al. 1999 Walsh et al. 1998), whereas it shows an estrogenic antagonist effect on reproductive organs such as the... 

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