Charybdis, only the thoralic dynasty received a longevity potion from Icewing/Ghostwalker. And it seriously messed with their fertility... And as for the Denairastas clan, you know what he was banished for and named Outcast? For having offspring with the 'lesser races', and messing with True Drakes.
And any Immortals would have to be - according to ED canon - either Dragon or Horror induced. Even epic spells of the 15-th Circle can't cheat death...