[india-drug] Re: Drug Query-Centchroman (5)

["Man Mohan Singh" <singhmm@rediffmail.com>]

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Re: Drug Query-Centchroman (5)
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Dear Ms. Sampada Patwardhan,

This is with reference to your email dated 12 June 2005 regarding centchroman.  The overall picture of centchroman given and what differentiates it from steroidal contraceptive pills (OCs) is all right.  But the term "aborted" used in your communication is inappropriate. The correct terminology would be that centchroman prevents implantation of the blastocyst (or that centchroman is an anti-implantation agent).  The term "aborted" is used only when there is an arrest of the development of physiologically implanted embryo and the maternal uterine endometrium, resulting in expulsion of the products of implantation (both maternal and embryonic) from the uterus. The term used in the communication "aborted" in reference to centchroman is thus scientifically incorrect.  Since this note is going to be comprehensive, it may be more appropriate to give a complete and correct picture of this aspect, which is given below:
Centchroman does not prevent the user from ovulating and the egg can be fertilized but centchroman will not allow this fertilized egg to be implanted and prevents pregnancy. Steroidal contraceptives (OCs) prevent pregnancy by inhibiting ovulation and thus fertilization.  The distinction between steroidal oral contraceptive pills (OCs) and this nonsteroidal once-a-week pill (Saheli) lies in that centchroman neither prevents ovulation nor fertilization but prevents implantation. 

Centchroman is a selective estrogen receptor modulator (SERM) having both estrogenic and antiestrogenic effects, which are tissue selective.  Its action on the reproductive tissues is primarily antiestrogenic, which has been demonstrated in a number of test models.  It inhibits uterotrophic action of estrone in ovariectomized rats and mice.  In adult ovariectomized rhesus monkeys, centchroman markedly inhibits estradiol stimulated 130 K fallopian tube fluid glycoprotein. In estrogen-deficient women with gonadal dysgenesis, concurrent centchroman treatment prevents stimulation of vaginal epithelium and uterine withdrawal bleeding caused by stilbestrol.  Its estrogen antagonistic effect appears to be via inhibition of formation of ER-ERE complexes and nuclear localization of estrogen receptor a, functional in the uterus. 

I tried to send as attachment my 2001 review on centchroman (Medicinal Research Reviews(21,302-347, 2001) and one more recent article demonstrating its antiosteoporosis activity in estrogen deficiency states and its possible beneficial effect in subjects taking centchroman for contraception/other endocrine diorders (J Steroid Biochem Mol Biol 91, 67-78, 2004), which I feel might have been of help, but my email was returned.

With best wishes

Yours sincerely,

Man Mohan Singh, Ph.D., D.Sc., FNASc 
Deputy Director 
Head, Endocrinology Division 
Coordinator, Reproductive Health Research Program 
Central Drug Research Institute 
Lucknow-226 001 
Tel.: 0522-2613894 (O), 2310757 (R) 
Fax: 0522-2623405
Email: "Man Mohan Singh" <singhmm@rediffmail.com>