I have a hard time imagining any chain letting you carry at work, but as I don't work for any big chains, I have no idea whether their guidelines specifically state that you cannot carry. Imagine the news if the media found out..."pharmacists packing guns, not pills", it'd be ridiculous. Unless you owned your own pharmacy or worked for an independent, I highly doubt it would happen. And as for hospitals, I think even with a carry permit, it's still prohibited, kinda like how you can't be carrying to school or a courthouse. Regardless, you'd have to do a lot of research on that, as well as the fact that coworkers might find out, the responsibility of carrying a firearm day in and day out, being prepared to shoot someone threatening your life and others, the possibility of hitting a bystander in a crowded pharmacy...it's tough.
Even if CCW wasn't specifically prohibited, if you ever clear leather for any reason, you might have to find a new job. Of course if you ever do that I would think a job would be the least of your worries, at least not until you deal with the police, prosecutors, possible civil suits, etc.
2 years ago, when someone killed a pharmacist at Shands in Jacksonville, we were just told to just have higher situational awareness and how to contact security...as if we didn't know before. I've been in my fair share of patient arguments, and it was pretty disconcerting to think about how someone could just come back with a burner and start shooting at us.
Of course, I'm sure there are those who keep them really concealed regardless of legality or if it's a gray area. You know, better to be caught with one, than be caught without one. I value my job and not being sent to pound-me-in-the-*** prison too much to do that, but some feel differently and value their life more, which I can understand.