My thread yesterday shows she was extremely drowsy & lethargic in the days and hours leading up to the massacre. As well as the months before.
Haldoperiodal is an extremeley powerful anti psychotic drug with dozens of side effects. One of them being that you become extremely lethagic, un cordinated and tired. Which would prevent psychotic outbursts.
The amount was reduced as the higher amount would have made her bedbound. As CC suggested. It was being injected so she could not skip taking tablets.