| abstract |
A pharmaceutical composition for the prophylaxis and therapy of brain tissue impairment, which contains, as an active ingredient, a compound of formula (I) wherein R1 represents an alkyl group having 1-4 carbon atoms or an aryl group having 6-10 carbon atoms which is optionally substituted; R?2 and R3¿ may be the same or different and each represents hydrogen or an alkyl group having 1-4 carbon atoms or R?2 and R3¿ may jointly form a ring having 3-7 carbon atoms; and R4 represents a lower alkyl group which is optionally substituted by aryl, cycloalkyl, or aromatic heterocyclic residue, or a pharmaceutically acceptable salt thereof. |