Regarding duloxetine (aka Cymbalta), I was always under the impression its appearance on the market was only due to the patent expiration of Prozac, and that the whole “pain relieving” aspect was just a new angle for marketing purposes.
Well, it is an SNRI. Sure, patent expirations are a motivator for drug R&D.
I agree, many patients say the pain relieving aspect doesn’t work so well.