EFFECTS OF 2 ANTIPROGESTINS ON EARLY-PREGNANCY IN THE LONG-TAILED MACAQUE (MACACA-FASCICULARIS)

Citation
Af. Tarantal et al., EFFECTS OF 2 ANTIPROGESTINS ON EARLY-PREGNANCY IN THE LONG-TAILED MACAQUE (MACACA-FASCICULARIS), Contraception, 54(2), 1996, pp. 107-115
Citations number
18
Categorie Soggetti
Obsetric & Gynecology
Journal title
ISSN journal
00107824
Volume
54
Issue
2
Year of publication
1996
Pages
107 - 115
Database
ISI
SICI code
0010-7824(1996)54:2<107:EO2AOE>2.0.ZU;2-G
Abstract
The abortifacient effects of mifepristone and HRP 2000 were compared i n gravid long-tailed macaques. Thirty-six animals were studied with tr eatment administered either by the oral (0.5 or 5.0 mg/kg; N = 5 per a ntiprogestin par dose) or intramuscular (IM) routes (0.5 mg/kg; N = 5 per antiprogestin) on gestational days (GD) 23-26; six vehicle control s were included. Blood samples were collected for assay of progesteron e (P-4) and each of the antiprogestins (pre-treatment, daily GD 23-28, every other day GD 30-40), and animals were monitored sonographically through out gestation. Results of these studies indicated high rates of abortion with IM administration (3/5 mifepristone, 4/5 HRP 2000) an d 5.0 mg/kg oral route (4/5, 2/5, respectively), with less effects not ed at oral doses of 0.5 mg/kg (2/5, 0/5, respectively). No early abort ions were observed in the control groups. Following daily IM treatment , peak levels of 8-16 ng/ml mifepristone were detected whereas 6-10 ng l mi of HRP 2000 were noted (GD 26-27). No serum levels of mifepriston e were detected following either of the oral doses whereas serum level s of 2-6 ng/ml HRP 2000 were noted with high dose oral administration. Results of these studies suggest: (1) both antiprogestins are roughly comparable in terminating early pregnancy although HRP 2000 may be mo re efficacious when administered IM whereas mifepristone may be more e ffective when administered orally; (2) similar levels of biological ac tivity are seen with the IM and high dose oral dosing regimens, with l ittle or no activity with the oral low dose; and (3) infants resulting from surviving pregnancies were not affected by early gestation expos ure.