PROBLEM TO BE SOLVED: To obtain the subject therapeutic drug which can excert inhibitory effects on the formation of fibrous condensate and the apoptosis and is useful in the treatment of spinal and medullary muscular atrophy, Huntington chorea or the like by using a compound having transgulutaminase inhibitory activity.
SOLUTION: This therapeutic drug includes a compound A (e.g. cystamine or monodansyl cadaverine) showing inhibitory activity to transglutaminase as an active ingredient. The therapeutic drug is obtained by pharmaceutical manufacturing using a substrate or a medium, e.g. a physiological saline, a sterilized water, a vegetable oil, an emulsifying agent, a suspending agent, a stabilizer or the like, and is administrated to patients of CAG repeat expansion disease, e.g. dentatorubral-pallidoluysian atrophy(DRPLA), Machado Joseph disease or the like, by means of intraarterial administration, intravenous administration, subcutaneous administration or the like.