Critical period of pyrimethamine teratosis in swine

• Published in: Japanese journal of pharmacology 1983, Vol.33, p.160-160
• Main Authors: Yamamoto, Yuzuru, Kokue, Ei-ichi, Izumi, Hideakira, Hayama, Toyoaki, Kaneda, Masahiro, Teramoto, Shoji
• Format: Article
• Language: English
• ISSN: 0021-5198; 1347-3506
• DOI: 10.1016/S0021-5198(19)60453-1

The teratogenic activity of pyrimethamine(PY) in Goettingen mini pigs was demonstrated by Misawa et al.(1980), who showed that the dose of 3.6mg/kg/day in feed during gestational days 11-35 proved to be teratogenic to swine. The present study was done to examine the incidence of malformation from dams given 3.6mg/kg daily (p.o.) with mashed feed in each of the following 4 subdivided organogenetic periods of pregnancy; days ll-22(group I, Slitters, 24 newborns), days 23-35(group II, 3 litters, 20 newborns), days ll-16(group III, 6 litters, 27 newborns) and days 17-22(group IV, 3 litters, 16 newborns). At farrowing, the newborn piglets having major malformations such as cleft palate, clubfoot, micrognathus etc. were killed and examined for internal abnormalities. Other newborns were observed for one week. The incidence of major malformation «as higher in group 1(54% of newborns), but that in other groups was low (0 - 14%). Newborns which had died within a few days were frequently observed in group 111(41%) and IV(38%).Splayleg was found in many of them. From these findings,it may be suggested that the pig fetuses were susceptible to PY when they were exposed to more than 6 consecutive days during the first half of the organogenetic period.