Novel prodrugs of MPV-2426, methods for preparing said prodrug forms, pharmaceutical compositions containing such prodrug forms, and methods for using the prodrug forms. A compound of general formula (I), or pharmaceutically acceptable salts or hydrates thereof, wherein R represents unsubstituted or substituted lower alkyl, unsubstituted or substituted aryl, unsubstituted or substituted cycloalkyl, unsubstituted or substituted heteroaryl, unsubstituted or substituted lower alkylamino or a saturated five or six membered heterocyclic group containing one or two nitrogen atoms.