Effect of Centchroman (67/20) and 78/224 on nucleic acid and protein biosynthesis during implantation in rats

Centchroman, a selective estrogen receptor modulator, as a contraceptive and for the management of hormone-related clinical disorders

DL-Centchroman (67/20; INN: Ormeloxifene) synthesized at the Central Drug Research Institute, Lucknow, is a nonsteroidal once-a-week oral contraceptive. It was introduced in Delhi in July, 1991, marketed in India in 1992 as Saheli and Choice-7 (Hindustan Latex Ltd., Thiruvananthapuram) and Centron (Torrent Pharmaceuticals India Ltd., Ahmedabad), and included in the National Family Welfare Programme in 1995.5 According to post-marketing surveillance, approximately 100,000 women were using this pill and approximately 1100,000 menstrual cycles were covered until 1996. It is a unique need-oriented contraceptive being effective when taken immediately after coitus or routinely as a weekly pill and has the advantage of less frequent administration. Its contraceptive action is quickly reversible. It has long terminal serum halflife of 168 hr in women and exhibits duration of anti-implantation/estrogen antagonistic action of 120 hr, despite a short (24.1 hr) serum halflife, in the rat. In lactating women, it is excreted in milk in quantities considered unlikely to cause any deleterious effect on suckling babies. In phase II and III multicentric trials as a contraceptive, children born of method-and-user failure pregnancies showed normal milestones, without any congenital anomaly. Reports of its promising action in the management of certain hormone-related clinical disorders are available. It has an excellent therapeutic index and is considered safe for chronic administration.

Effect of a pure nonsteroidal antiestrogen, CDRI-85/287, on implantation--associated histological and biochemical changes in the rat uterus

The effect of compound CDRI-85/287, a pure, nonsteroidal antiestrogen, on implantation-associated changes in rat uterus were studied. Results provide a clear correlation between the antideciduogenic action of 85/287 (0.05 mg/kg in days 1-5 post-coitum or 2.5 mg/kg on day 1 post-coitum) and the time of its administration in relation to the secretion of prenidatory luteal phase estrogen. The antiestrogenic nature of the compound is further highlighted by inhibition of estradiol-induced increase in vascular permeability. In the present study, differences in the pattern of biochemical maturation of the pregnant, pseudopregnant and 85/287-treated rat uterus have also been illustrated. As compared to the pregnant rat uterus, absence of (the blastocyst and) decidualizing tissue in the pseudopregnant rat uterus accounts for the low uterine weight, protein, RNA, phospholipids and alkaline phosphatase at the time of implantation. Post-coital treatment with 85/287 (2.5 mg/kg, oral) inhibited increase in these parameters at the time of implantation. Glycogen levels which were lowered in the pregnant rat uterus on days 5 and 6, remain unaltered in the pseudopregnant and 85/287-treated rat uteri, suggesting nonutilization of this energy substrate. These findings provide sufficient evidence that the antiimplantation activity of 85/287 is due to its antiestrogenic property.