Irvine-based drug maker Allergan Inc. is in advanced negotiations with potential “white knight” suitor Actavis PLC, according to a Bloomberg report Wednesday.

Talks are now centered on narrowing a gap of some $3 billion between what Actavis is offering and what Allergan wants. Actavis, which is headquartered in Dublin and operates from New Jersey, is willing to pay $60 billion, or $200 a share, while the Botox maker wants $210 a share.

In midday trading Thursday, shares in both Allergan and Actavis were mostly flat with a market value of $58.3 billion and $63.8 billion, respectively. Shares of Allergan's hostile suitor Valeant Pharmaceuticals International Inc. were also flat at a market value of $43.5 billion.

Allergan is negotiating with Actavis as it fights off a hostile takeover bid by Valeant and activist investor Bill Ackman’s Pershing Square Capital Management LP.

Valeant and Ackman have offered $54 billion in cash and stock but Ackman has said he and Valeant would be willing to work from a benchmark of $60 million if Allergan would come to the negotiating table.

Allergan, in a separate matter, changed its bylaws covering calling a special shareholders’ meeting ahead of a scheduled Dec. 18 special meeting at which investors would vote on a proposal by Ackman, who wanted a rule change allowing investors who requested the meeting to set the date for it.

The drug maker said in a statement that the amended bylaws now include a provision that requires Allergan's board to call for a meeting within 90 days of a valid request rather than exercise its discretion.