Pershing Square nominated Betsy Atkins, chief executive officer of venture capital firm Baja; Cathleen Black, senior adviser at RRE Ventures who was also a former chancellor of New York City's public schools and a former president of Hearst Magazines; Fredric Eshelman of investment firm Eshelman Ventures; Steven Shulman, managing director of Shulman Ventures, a private equity firm; David Wilson, former CEO of the Graduate Management Admission Council, and John Zillmer, former executive chairman of chemicals distributor Univar Inc.

Allergan is best known for Botox, an anti-wrinkle injection. Botox is also used to treat other medical conditions, including chronic migraine headaches.

Pershing Square is pushing for a special meeting of Allergan shareholders to consider the removal of six incumbent directors and the appointment of its slate of nominees.

Canada's Valeant has said it already has enough shareholders on its side to call the meeting. It would need the support of holders of at least 25 percent of the shares.

Allergan, based in Irvine, California, said its current board includes people with significantly more industry experience than Pershing Square's nominees.

"We believe today’s announcement is a further attempt by co-bidders Pershing Square and Valeant to acquire Allergan at a grossly inadequate price that substantially undervalues the Company and creates significant risks and uncertainties for Allergan stockholders," an Allergan spokesperson said.

Allergan is expected to unveil details of its plan to remain a stand-alone company when it releases second-quarter results sometime in July. The company has said it is considering acquisitions of its own, additional spending cuts or taking on debt to buy back shares.

(Reporting by Susan Kelly in Chicago; Editing by Jan Paschal)