Ethinylestradiol administered by oral and sublingual routes: a comparative study in ovariectomized women

Eight ovariectomized women with an intact uterus received 12.5 micrograms ethinylestradiol for 14 days, in a cross over fashion. Ethinylestradiol was administered as a paper disc for sublingual application or as a tablet for oral administration. The parameters studied were FSH secretion, plasma protein synthesis, endometrial morphology, cervical mucus properties and the karyopyknotic index. Both types of treatment resulted in estrogenic effects with a more pronounced effect on sperm penetration and the Spinnbarkeit test after paper disc treatment than after conventional tablet treatment. The post-treatment FSH concentration 20 h after ethinylestradiol administration was significantly lower than the pretreatment value only in the case of the paper disc treatment. There was no evidence of any difference in effects on protein synthesis. The results indicate that the availability of ethinylestradiol for peripheral tissues may be increased by sublingual administration compared to oral tablet administration, whereas the effects on liver protein synthesis may remain unchanged.