Shares of Zogenix (NASDAQ:ZGNX) took an awful 20% haircut today, on news emerging from a potential competitor. Zogenix's new super painkiller, Zohydro, is extremely potent and effective, normally a positive thing for a drug, but an advisory panel overwhelmingly rejected the drug, because of its potential for abuse. Despite the rejection recommendation, the FDA approved the drug, which up until now has had no abuse-resistant alternative.

Now, however, private company Purdue Pharma, best known for making oxycontin, has an abuse-resistant version of Zohydro. The company did the same thing for oxycontin, which kept non-abuse-deterrent generics of the drug off the market.

In this video, Motley Fool health-care analyst David Williamson outlines two major possible concerns from here for Zogenix and its drug. The first is that doctors would be more likely to prescribe Purdue's version of the drug because of the added anti-abuse feature, and the second is that with all of the backlash around Zohydro, the FDA may consider rescinding its approval of the drug. Zogenix's stock has seen a huge run, but with its fate now partially out of its hands, David sees this as a stock to avoid.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.