The Collaborative International Dictionary of English v.0.48:
drained \drained\ adj.
   having lost much energy or emotion from vigorous activity; --
   of people; as, the day's events left her completely drained
   of strength.
   [WordNet 1.5]
   2. having resources completely depleted.
   Syn: depleted.
        [WordNet 1.5]
   3. having no power remaining; -- of a battery.
   Syn: run-down.
        [WordNet 1.5]
   to go down the drain
   1. to be consumed in profitless activity; to be wasted; to
      become worthless.
   2. to vanish or cease existing.
      [PJC]