Have we had an alcoholic character in Star Trek, aside from Damar (and even that was fairly subtle)?
I'd say Scotty. That, of course, is implicit.
Great comic scene in "By Any Other Name," where Scotty literally holds the future of all sentient life in our galaxy, but can't make it to the door of his quarters. Extenuating circumstances? Yeah. But you know how you develop
the tolerance to drink someone under the table to the tune of (at least) several bottles of brandy and whiskey?