My thought is that this is total bull****. You by far get more fluoride from drinking water, than taking prozac.
Reason is it depends on how the fluorine is attached and in the molecule. Unless you know the exact reaction that Prozac has in the liver, etc. that it is metabolized by, and then that fluorine is released into the body, then this has no weight.
In order for fluoride poisoning to occur, a compound must release fluoride (F−) ions. Whereas most organofluorine compounds may not release F− because of the strength of the carbon–fluorine bond and its tendency to strengthen as more fluorine atoms are added to a carbon, others do, such as methoxyflurane. The fluorine atom is pervasive in drugs, e.g. Prozac, and many other substances such as freon, Teflon, and blood serum (PFOS, PFOA, and PFNA). Organofluorine compounds, however, that are fluoroalkane based do not release F− under biological conditions because of their stability.
Basically because there are 3 fluorine attached to the carbon, they're not coming off. You don't have anything to worry about.