Abstract
Summary
The intestinal absorption of 3 natural pyrimidines and of 17 2-thiopyrimidines was studied in intact rats, and the antithyroid activity of 12 of the latter compounds tested by subcutaneous injection. With the possible exception of uracil, all compounds tested were passively absorbed. No relation was found between intestinal absorption and adsorption, and among compounds showing oral antithyroid activity, no relation was found between this activity and absorption. Both absorption and antithyroid activity were decreased by ionization or by polar groups, while small, non-polar groups had little or no effect on absorption. The position of the groups was of minor importance. It is suggested that the rate of intestinal absorption, for any series of similar, water-soluble compounds, is inversely related to polarity.
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