A point of clarification.

"Some drugs do contain fluorides..prozac for one."

Some drugs, like Prozac and the fluoroquinolone class of antibiotics contain the element fluorine (F) linked in a covalent bond to the element carbon (C). The C-F bond is very strong - it is very unlikely that it will be cleaved during drug metabolism.

The anion fluoride (F-) is a controversial additive to drinking water in some places. The fluoride anion and a fluorine atom linked in a covalent bond to a carbon atom have very different chemical properties - fluorine and fluoride are not the same thing.