Biopharmaceutical studies on hydantoin derivatives. I. Physico-chemical properties of hydantoin derivatives and their intestinal absorption.
The physico-chemical properties of a series of hydantoin derivatives and their intestinal absorption from solution were studied. The introduction of the benzenesulfonyl group at the 1-position of the hydantoin ring greatly affects the physico-chemical properties: the acid dissociation constants were increased 1000-fold and the partition coefficients were increased 100- to 1000-fold in the chloroform/water system and 10- to 100-fold in the n-octanol/water system. The solubilities of 1-benzenesulfonylhydantoin derivatives increased with increasing pH of the solution  at pH more than 5, but the solubilities of the 1- unsubstituted hydantoin derivatives were scarcely dependent on the pH of the solution in the pH 1 to 8 region. The intestinal absorption from solution was found to be caused by the passive transport according to the first-order kinetics. The rate constants of absorption of 1-benzenesulfonylhydantoin derivatives were rather large even under the condition where they were 99% ionized in the solution than that of the corresponding 1-unsubstituted hydantoin derivatives which exist mainly as the unionized from under the same condition. The intestinal absorption from a solution and the partitioning to chloroform produced linear free energy relationships to each other for the 1-benzenesulfonylhydatoin derivatives and for the 1-unsubstituted hydantoin derivatives independently. However when the partition coefficients in the n-octanol/water system were applied, the hydroxyl derivatives were found to deviate from linear relationships. On  the basis of the results, a suggestion was made on the in vivo behavior and the bioavailability.
D000818:Animals; D001702:Biopharmaceutics; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004355:Drug Stability; D006827:Hydantoins / Q000097:blood / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007408:Intestinal Absorption; D051381:Rats; D011919:Rats, Inbred Strains; D012995:Solubility
D006827:Hydantoins