Dragons I would think are on a entirely different level BUT I just used 2 damage stamina regen (100%) potions on a Dragon (master lvl) when he had 75% health left and it put him down for good, I think that he was a weaker one but the point is that they worked.
Now I just acquired a 40 pt. magicka damage Bow and a 20 pt. Absorb sword that im going to try because even though the Dragon could'nt fly he was still spitting fire.
Has anybody had exp. with these types of weapons/ potions on a dragon? I would just like to compare notes after I try, I did a search but everything was very generalized, you know "just put him down fast and whack em with a big knife" or "fill him full of arrows".