| 摘要 |
A piperazine derivative of the formula: <IMAGE> wherein R1 is a hydrogen atom or a lower alkyl group; R2 is a hydroxyl group, an aralkyloxy group, a lower alkoxy group containing 1-5 carbon atoms or a lower alkenyloxy group containing 3-5 carbon atoms; R3 is a hydrogen atom, or an aralkyloxy group, a lower alkoxy group containing 1-5 carbon atoms or a lower alkenyloxy group containing 3-5 carbon atoms; and R4 is a hydrogen atom or a lower alkoxy group containing 1-5 carbon atoms, provided that R2 is a group other than the lower alkoxy group containing 1-5 carbon atoms when both R3 and R4 are hydrogen atoms; or a pharmaceutically acceptable salt is effectively useful as a cerebral circulation-improving agent. |
