The present invention provides a hypotoxic pharmaceutical composition having exellent effect of physical property and dynamics in vivo, and can reduce the number of peripheral blood cell and lymphocyte.A pharmaceutical composition having a compound of the following formula (I)[wherein, R1represents methyl group or ethyl groupR2represents methyl group or ethyl groupR3represents a phenyl group substituted by 1-3 substituents selected from a group consisting of a halogen atom, a lower alkyl group, a cycloalkyl group, a lower alkoxyl group, a lower halogenoalkyl group, a lower aliphatic acyl group and a cyano group〕, the pharmaceutically acceptable salt or the pharmaceutically acceptable ester thereof.
