ination riddle!! Good enough?

Dave and Brad, two popular politicians, met at a club to discuss the overthrow of their party leader. They each ordered a vodka on the rocks. Brad downed his and ordered another. He then drank his second in a gulp and decided to wait before he ordered a third. Meanwhile, Dave, who was sipping his drink, suddenly fell forward dead. Both men were setup for an ination. Why did Dave die and Brad live?