Distribution of tritium-labelled tofenacine hydrochloride in the pregnant mouse

The distribution of tritium-labelled tofenacine hydrochloride after oral administration to pregnant mice was studied by means of a macroautoradiographic procedure. The distribution of radioactivity showed many points of resemblance with that in nonpregnant female mice, such as retention of the administered radioactivity in the stomach resulting from its atropine-like activity and a lower concentration of absorbed radioactivity in blood than in practically all the other organs. High levels were especially reached in the lungs, Harder's glands, thymus, lymph nodes, certain zones in the kidneys and adrenals, and to a lesser extent in the liver, salivary glands and bone marrow. A distinct penetration of radioactivity into the foetus was observed at the three periods gestation studied, namely 15, 17, and 19 days, although no correlation between these periods and the measure of penetration could be established. The placenta and especially the foetal membranes also showed a marked concenration of radioactivity. In mice pregnant for 19 days a foetal distribution pattern of radioactivity similar to that of the mother, was particularly striking. In the foetus of mice pregnant for 15 and 17 days, the differences in radioactivity between the various foetal organs were less pronounced. Various aspects of these findings are discussed.