The pharmaceutical company Vivus has announced the resignation of its chief executive officer (CEO) Anthony Zook. The former PLC executive for AstraZeneca cited "recurring issues associated with a previously diagnosed medical condition" as his reason for leaving Vivus just a month after being appointed CEO.

"This has been a difficult decision," Zook said in a statement. "Unfortunately, I cannot devote the necessary time and focus to the company, but instead must concentrate on personal health issues."

Back in July, Zook was named CEO after a lackluster financial start for Qsymia, the second obesity drug approved in the United States. Vivus shareholder First Manhattan Co. suggested Zook for the position due to his success with multibillion-dollar cholesterol medicine Crestor, Reuters reported.

Following Zook’s decision to resign, the board at Vivus named Seth H.Z. Fischer the company’s new CEO. Fischer, former senior executive at Johnson & Johnson, is credited with three decades of healthcare experience, including marketing success with the epilepsy and migraine drug Topamax.

"VIVUS is keeping Tony in its thoughts and we wish him a rapid recovery. We are grateful for his contributions and his willingness to work with Seth through mid-September 2013 to assist with the transition," explained Michael Astrue, chairman of Vivus.

"We are pleased to welcome Seth Fischer to VIVUS and look forward to his leadership as we continue to execute on our four goals: 1) expand use of Qsymia through targeted patient and physician education; 2) find the right partner for Qsymia; 3) quickly create a pathway for approval in Europe; and 4) eliminate expenses that are not essential to expanding use of Qsymia."