The Gaithersburg, Maryland-based biotechnology company, which has been the subject of takeover rumors for months amid investor agitation, said it has authorized management to "evaluate whether third parties would have an interest in acquiring the company at a price and on terms that would represent a better value for its stockholders than having the company continue to execute its business plan on a stand-alone basis."
Talk of a bid for MedImmune has been intensifying since billionaire investor Carl Icahn disclosed in February he owned 2.8 million shares of the company.
The stock has risen 20% since then.
MedImmune, one of the larger independent biotech firms in the United States, is best known as the maker of the nasal spray flu vaccine FluMist but it also has two other marketed products -- respiratory drug Synagis and Ethyol for reducing chemotherapy toxicities.
The company announced on Monday it expected first-quarter earnings to have tripled, driven by higher-than-expected sales of Synagis, which has had reimbursement problems in the past.
One person familiar with the situation said MedImmune could fetch a hefty premium, since it is a relative rarity among biotech firms in already having commercial biologic products.
That may make it attractive to a number of large drugmakers looking to bolster their portfolios, industry sources said.
Potential acquirers could include Merck , Wyeth , Eli Lilly and Abbott Laboratories among U.S. pharmaceutical groups, the sources said.
In Europe, Novartis is seen by some as potential suitor, although one person familiar with the situation said the Swiss firm was not interested.
Novartis earlier on Thursday announced it was selling its Gerber baby-food business for $5.5 billion to Nestle to focus fully on healthcare.
AstraZeneca , which is hungry for assets to refill a depleted new drugs pipeline, is also a possible suitor but GlaxoSmithKline is viewed as unlikely.
Officials at these companies declined to comment or were not immediately available to respond.