TY - JOUR T1 - THE DISTRIBUTION OF THIOPENTAL-2-C<sup>14</sup> IN MATERNAL AND FETAL TISSUES OF THE RAT JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 164 LP - 173 VL - 158 IS - 1 AU - Paul J. Schechter AU - Lloyd J. Roth Y1 - 1967/10/01 UR - http://jpet.aspetjournals.org/content/158/1/164.abstract N2 - Radioactivity in various maternal and fetal tissues of 21-day-pregnant rats following maternal i.v. injection of C14-thiopental has been measured and whole-body autoradiograms of these pregnant animals have been prepared. The placenta acts as a relative barrier to protect the fetus from the high maternal plasma concentration of thiopental which is anesthetic to the mother. Maternal blood levels of thiopental fall rapidly as the drug enters maternal tissue. The delay imposed by the placenta during the period of falling maternal plasma levels results in a lower fetal plasma concentration than that presented to the maternal central nervous system during the first few minutes following injection. Only unchanged thiopental-2-C14 has been found in methylene chloride extracts of the maternal and fetal tissues assayed. © 1967 by The Williams &amp; Wilkins Company ER -