Placental Transfer of Sulfamethazine in Mice and Rats

SimunekJ., A. B. Siddique, E. Hegerova: Placental Transfer of Suljamethazine in Mice and Rats. Acta Vet. Brno, 47,1978: 145-151. Placental transfer of sulfamethazine in mice was investigated in the second half of their pregnancy. The transfer was not free but only a part of the drug administered to mothers was found to pass from the maternal circulation to the fetus. Placental transfer of sulfamethazine in rats was investigated at two stages of gestation early (8th to 10th day) and late (18th to 20th day of gestation). Ther~ was free and rapid passage of the drug from the maternal circulation to the fetus at the early stage of gestation. But the passage was found to be greatly reduced at the late stage of gestation. The drug also appeared in the amniotic fluid. Mice, rat, placenta, fetus, transfer, suljamethazine~· The placenta in unique is its function. Its life time is short relative to the fetus, and its size and function change continually during the course of gestation (Wynn 1968). The study of the placental transfer of drugs is of paramount importance because much of intrauterine fetal welfare depends on the exchange processes of these substances through the placenta. Sulfonamides have been reported to easily pass through both human and animal placenta (Lee, Anderson and Chen 1938; Friesen 1951; Siddique and Simunek 1977). The possible use of these drugs for intrauterine therapy as well as for fetal prophylaxis and their effects on the fetus and newborn make it necessary to know and understand the degree. and extent of transplacental passage of these drugs. The present paper reports on the placental transfer of sulfamethazine in mice in their second half of pregnancy and in rats at two stages of pregnancy. Materials and Methods White mice and Wistar rats were obtained from the Biological Research Center, Konarovice near Prague. Sulfamethazine used was a product of Czechoslovak national pharmaceutical enterprise, Spofa. Procedure for mice 13 mice which were 15 to 18 days pregnant were divided into two groups and injected intramuscularly a freshly prepared 2 % solution of sodium-sulfamethazine at the dose of 0.2 g/kg body mass. One group of mice was killed after 2 hours and the other group after 24 hours of drug administration. Samples of blood, placenta and fetus of each group of mice were collected and their sulfamethazine concentrations measured. In all there were 70 fetal samples. Simultaneous control experiment with 5 nonpregnant adult female mice was carried out. Procedure for rats Two independent experiments were done. In both cases, transfer was studied at two stages of gestation.