In the following video, Motley Fool health-care analyst David Williamson discusses Zoegenix's (ZGNX) 30% leap, as the FDA delays approval for its pain medication Zohydro. A delay would make very little sense if the FDA were planning to reject the drug, and the company has stated that the FDA says this delay will be brief. David tells us why this is surprising, and what is driving the market's reaction.