First Manhattan fought a protracted battle with Vivus management, claiming it had botched the launch of obesity drug Qsymia. Since approval midway through July 2012, shares of Vivus have plunged more than 50% as the drug has struggled to find traction in the market.

First Manhattan argued that its new board would help find a marketing partner as competitor Arena Pharmaceuticals has with its competing product Belviq, and it won enough support that an agreement between the company and the hedge fund culminated in the resignation of six board members arrival of a new CEO, Tony Zook. But after roughly a month on the job, Zook stepped down for health reasons. Does this development potentially throw Vivus off course?

In this video, health-care analyst David Williamson discusses why Vivus investors shouldn't be worried over the news, given management's turnaround plan and, more importantly, the fact that ever since Qsymia was allowed in retail pharmacies, its sales have showed strong growth.