Effects of two antiprogestins on early pregnancy in the long-tailed macaque (Macaca fascicularis)

Alice F Tarantal, Andrew G Hendrickx, Stephen A. Matlin, Bill L. Lasley, Quin Quin Gu, Charles A A Thomas, Pamela M. Vince, Paul F A Van Look

Research output: Contribution to journalArticle

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Abstract

The abortifacient effects of mifepristone and HRP 2000 were compared in gravid long-tailed macaques. Thirty-six animals were studied with treatment administered either by the oral (0.5 or 5.0 mg/kg; N = 5 per antiprogestin per dose) or intramuscular (IM) routes (0.5 mg/kg; N = 5 per antiprogestin) on gestational days (GD) 23-26; six vehicle controls were included. Blood samples were collected for assay of progesterone (P4) and each of the antiprogestins (pre-treatment, daily GD 23-28, every other day GD 30-40), and animals were monitored sonographically throughout gestation. Results of these studies indicated high rates of abortion with IM administration (3/5 mifepristone, 4/5 HRP 2000) and 5.0 mg/kg oral route (4/5, 2/5, respectively), with less effects noted at oral doses of 0.5 mg/kg (2/5, 0/5, respectively). No early abortions were observed in the control groups. Following daily IM treatment, peak levels of 8-16 ng/ml mifepristone were detected whereas 6-10 ng/ml of HRP 2000 were noted (GD 26-27), No serum levels of mifepristone were detected following either of the oral doses whereas serum levels 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 more efficacious when administered IM whereas mifepristone may be more effective when administered orally; (2) similar levels of biological activity are seen with the IM and high dose oral dosing regimens, with little or no activity with the oral low dose; and (3) infants resulting from surviving pregnancies were not affected by early gestation exposure.

Original languageEnglish (US)
Pages (from-to)107-115
Number of pages9
JournalContraception
Volume54
Issue number2
DOIs
StatePublished - Aug 1996

Fingerprint

Mifepristone
Macaca fascicularis
Macaca
Pregnancy
Abortifacient Agents
Induced Abortion
Serum
Progesterone
Oral Administration
Therapeutics
ulipristal
Control Groups

Keywords

  • abortion
  • HRP 2000
  • mifepristone
  • monkey
  • pregnancy
  • progesterone
  • RU 486

ASJC Scopus subject areas

  • Medicine(all)
  • Obstetrics and Gynecology

Cite this

Tarantal, A. F., Hendrickx, A. G., Matlin, S. A., Lasley, B. L., Gu, Q. Q., Thomas, C. A. A., ... Van Look, P. F. A. (1996). Effects of two antiprogestins on early pregnancy in the long-tailed macaque (Macaca fascicularis). Contraception, 54(2), 107-115. https://doi.org/10.1016/0010-7824(96)00134-5

Effects of two antiprogestins on early pregnancy in the long-tailed macaque (Macaca fascicularis). / Tarantal, Alice F; Hendrickx, Andrew G; Matlin, Stephen A.; Lasley, Bill L.; Gu, Quin Quin; Thomas, Charles A A; Vince, Pamela M.; Van Look, Paul F A.

In: Contraception, Vol. 54, No. 2, 08.1996, p. 107-115.

Research output: Contribution to journalArticle

Tarantal, AF, Hendrickx, AG, Matlin, SA, Lasley, BL, Gu, QQ, Thomas, CAA, Vince, PM & Van Look, PFA 1996, 'Effects of two antiprogestins on early pregnancy in the long-tailed macaque (Macaca fascicularis)', Contraception, vol. 54, no. 2, pp. 107-115. https://doi.org/10.1016/0010-7824(96)00134-5
Tarantal, Alice F ; Hendrickx, Andrew G ; Matlin, Stephen A. ; Lasley, Bill L. ; Gu, Quin Quin ; Thomas, Charles A A ; Vince, Pamela M. ; Van Look, Paul F A. / Effects of two antiprogestins on early pregnancy in the long-tailed macaque (Macaca fascicularis). In: Contraception. 1996 ; Vol. 54, No. 2. pp. 107-115.
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