That's not what they're looking for in your checked luggage.
My only suggestion is don't make it a pharmacy, and don't try to hide it. Put them in a shaving kit or something. Do the vials LOOK illegal? I guarentee that noone at TSA is going to know what 2 vials of NPP are. But can they mistake them for something more suspicious?
You can keep firearms in your checked luggage. Do you think they're going to notice 4 pins and some clomid?
TSA is not the cops. They are looking for explosives in your checked luggage, and anything that could be used to compromise the security on a plane in your carry-on. If the pins were in your carry-on, they could be used to inject the pilots and crew with something dangerous. In your checked bag, however, nobody has access to it. So you can have just about whatever you want in there.
But as always, you're taking the chance. If you're going through Bumblefuck, Iowa, they may search everyones bag because they have nothing better to do. Will they catch it? I wouldn't bet on it. If you're going through someplace like Ohare or LaGuardia, they won't open a bag unless they absolutely have to.