what are neuroleptic thioxantene derivates?

Answer 1

these are medications used as antipsychotics or in neuroleptic anaesthesia

hmmm

looking at the list of them, I've never seen them used in neuroleptic anaesthesia - other antipsychotics have been used though

The derivatives are either metabolites or other drugs made by adding on functional side chains to the parent drug molecule. (Metabolites are much the same thing, just done by your liver)

Most metabolites are still metabolically active, although some are not. The laboratory produced derivatives are selected to have biological activity.