If they make people automatically do the right thing, then they stop being genuinely moral... Even if they drugs stopped people from murdering people, I think [Kant] would be opposed.
I can imagine, though, a drug that actually enhances morality. Maybe on your mental blackboard the moral law is getting faded and smudged and the drug improves matters. Maybe you’re too hyperactive to read the mental blackboard and it calms you down. I can see how there could be Kant-approved drugs that improve morality. I’m sure that should be included in the drug label…
I call 'bollocks' on this distinction. We automatically do the right thing all the time. It's right not to spit at passersby, not to use babies as footballs, not to stab the person sitting next to you, etc. More positively, it's also right to comfort your partner when she's upset, listen attentively to an interesting lecture, and respond promptly to emails. Many of us happily conform to these requirements "automatically". Some people don't, and are to this extent morally defective (mildly so in the case of lazy communication, more seriously for the spitting and stabbing psychopaths) -- even those who manage, after some internal struggle, to bring themselves into line with the 'moral law'.
Sure, it's better to act rightly than wrongly. But better yet to never suffer the contrary inclination in the first place. Cf. Aristotle on the virtuous vs. the merely continent. [Update: this point may also be used to prove the non-existence of a benevolent God.]
The self-constrained psychopath is not more "genuinely moral" than the rest of us. (Kant got this one wrong. Granted, acting from duty may be better - because more reliable - than acting from whimsical inclination. But compared to acting from well-cultivated virtues of character? You've got to be kidding me.) Quite the opposite. For the same reason, I think it's a mistake to think that we would somehow stop counting as 'genuinely moral' if a drug recalibrated our faulty inclinations so that right action came more naturally to us. That's just what it is to truly be -- and not just act -- virtuous.