Forest Laboratories Inc's showdown with activist investor Carl Icahn should be resolved on Thursday, when shareholders meet to pick the drugmaker's new board of directors.

The company is in a stronger position to garner support for its entire 10-member slate after it won backing last week from influential proxy advisory firm ISS, although some say Icahn has a chance at securing a seat for one of his four nominees.

The billionaire has built up the second-largest stake in Forest, according to Thomson Reuters data. He has criticized the company's governance practices and preparation for patent expirations for its biggest medicines.

Forest's slate includes three new board members nominated after Icahn announced his challenge. Two longtime directors are not standing for reelection.

A Forest board sweep would be a victory for Chairman and Chief Executive Officer Howard Solomon, who has led the company since 1977. Earlier this month, the U.S. government dropped plans to bar Solomon from doing business with federal healthcare programs, weakening a key plank in Icahn's argument for change.

ISS and another proxy advisor, Egan-Jones, backed Forest's entire slate. Glass Lewis recommended Icahn nominee Richard Mulligan, a Harvard Medical School genetics professor who sits on the boards of biotech companies Biogen Idec Inc and Enzon Pharmaceuticals Inc .

Icahn said last week that he had increased his stake to 9.2 percent from about 7 percent when he revealed his board challenge in June. He ranks second behind Wellington Management, which has a 12.5 percent stake, according to data compiled by Thomson Reuters.

Analysts expect revenue at New York-based Forest to drop by about one-fourth after its Lexapro antidepressant loses patent protection early next year. Its Namenda Alzheimer's drug is set to lose patent protection in 2015.

Forest has a market value of about $10 billion. Its shares are worth less than half of what they were at their height in 2004 and about 40 percent less than peak 2007 levels.

(Reporting by Lewis Krauskopf; Editing by Lisa Von Ahn)