Falkenrath Gorger says:
Each Vampire creature card you own that isn't on the battlefield has madness.
Now the madness has already triggered since Drana was discarded as part of the cost of the discard effect. However madness has been lost between placing Drana into exile and before casting her.
Can the player still play Drana from exile or is she stuck there now she has lost madness?
Bonus question (I'm fairly sure the answer is no) - if she is stuck in exile would playing another Gorger allow her to be cast from exile again?