US pharmaceutical producer Allergan, fighting a hostile bid from Quebec-based rival Valeant, has said it plans to cut 1,500 job or 13% of its workforce as part of a restructuring effort aimed at boosting profits over the next six years.

The drugmaker whose best known product is the wrinkle treatment Botox said the cost reductions are intended to convince investors that it is a better value as a standalone company and would help increase annual earnings more than 20% annually between 2014 and 2019.

Valeant and the Pershing Square Capital Management vehicle of activist shareholder Bill Ackman made a $52 billion hostile offer for Allergan in April, but the company has said repeatedly the deal is not in the best interest of shareholders.

The restructuring, which is projected to create savings of $475 million in 2015, would also eliminate about 250 vacant positions.

Allergan is also weighing a number of strategic options to counter Valeant, including stock buybacks and acquisitions.

In a conference call with investors, Allergan CEO David Pyott, said it would be difficult for his company to buy competitors with the types of products it now sells - which include dermal fillers, breast implants and prescription eye drugs - because it is already a dominant player in those markets.

However, he said Allergan is interested in buying one or more different types of businesses which would become "new pillars" of the company.

On US television, Ackman charged that such acquisitions would be "desperate" moves and that Pershing Square would sue Allergan if such attempts were made. Separately, Valeant said it had complained to financial market regulators in Canada and the US about "false and misleading statements" that Allergan has made about its business.

The US drugmaker which emphasizes research spending, said its restructuring would lead to the cancellation of at least four early-stage drug development programs in eye-care and dermatology but it would not reduce projects now in human trials. Valeant is known for slashing research spending at companies it acquires and has proposed to do so at Allergan if the acquisition is successful.

The two companies are fighting for shareholders' votes even as those investors are buying and selling stakes. Hedge fund Paulson & Co bought more than 6 million shares of Allergan, sources told the news agency Reuters last month. Additionally, the Wall Street Journal reported that Capital Research and Management had sold off almost all of a stake that once exceeded 6 %.