Action of midcycle contraceptive (R 2323) on the human endometrium.
Over 2,148 cycles of midcycle oral administration of R 2323 (50 mg. per day on Days 15,16, and 17), the authors recorded a drug-failure pregnancy rate of 5 per cent and an unusually regular cycle length of 28 +/- 2 days. During this trial, endometrial biopsies obtained in the luteal phase were examined by light and electron microscopy and compared to pretreatment biopsies. Light microscopy indicated a weakly secretory endometrium suggestive of some, albeit low, progesterone impregnation. Ultrastructural examination revealed deleterious changes in the development of the nucleolar channel system and giant mitochondria and a delay in the migration of glycogen granules. This low progesterone impregnation could be explained either by a direct effect of R 2323 on cell ultrastructure or by interference with progesterone availability. It would appear that R 2323 acts as a temporary substitute for progesterone at the receptor level but that it does not induce all the biological manifestations of this hormone, in particular, the endometrial changes required for implantation.
D001706:Biopsy; D002466:Cell Nucleolus / Q000187:drug effects; D002986:Clinical Trials as Topic; D003276:Contraceptives, Oral / Q000494:pharmacology*; D003280:Contraceptives, Oral, Synthetic / Q000494:pharmacology*; D004717:Endometrium / Q000187:drug effects* / Q000648:ultrastructure; D005260:Female; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D008598:Menstruation; D008928:Mitochondria / Q000648:ultrastructure; D009645:Norgestrienone / Q000031:analogs & derivatives* / Q000494:pharmacology; D009651:Norpregnatrienes / Q000031:analogs & derivatives*; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D013997:Time Factors
D003276:Contraceptives, Oral; D003280:Contraceptives, Oral, Synthetic; D006023:Glycoproteins; D009651:Norpregnatrienes; D011374:Progesterone; D009645:Norgestrienone