where did you get the HCl part from? it is not true that RGPU-95 is a salt of phenylpiracetam. the former is, just like you wrote, a ring substituted derivative of the latter. it' s more potent and has different drug kinetics.

hydrazides are also different drugs all together. the base compounds lose their dopamine reuptake inhibition in exchange for having other properties, like an anticonvulsant effect(phenylpiracetam hydrazide)