Studies on the effects of pharmacologic doses of cortisone acetate and several nonsteroidal anti-inflammatory compounds on ovo-implantation, early pregnancy, and the deciduomal response in the rat.

Cortisone acetate (10 mg/day), alone or in combination with progesterone (4 mg/day); progesterone (4 mg/day); progesterone (4 mg/day) plus estrone (1 microng/day); indomethacin (0.75 mg/day); phenylbutazone (20 mg/day); flufenamic acid (10 mg/day); and Compound 83161 (tetrazolo less than 1,5-alpha greater than s-triazolo less than 3,4-c greater than quinoxoline) (8 mg/day and 12 mg/day) were each given to intact rats during early pregnancy (days 1 and/or 2 through day 8). Only cortisone acetate treatment caused a true delay in ovo-implantation. Both progesterone treatment beginning on day 1 and cortisone acetate treatment beginning on day 1 or 2 caused an increased postimplantation fetal death rate. Compound 83161, at doses causing signs of general toxicity (12 mg/day), caused a marginal inhibition of implantation. Treatment with indomethacin, phenylbutazone, or flufenamic acid caused some inhibition of the traumatic deciduomal response in spayed rats treated with progesterone, while treatment with cortisone acetate and Compound 83161 did not.