Pfizer Inc. (PFE), the world's biggest drugmaker, on Thursday agreed to buy Vicuron Pharmaceuticals Inc. (MICU), a development-stage biotechnology company, for $1.9 billion in cash to broaden its lineup of anti-infectives.

New York-based Pfizer (search) will pay $29.10 in cash for each share of Vicuron (search), which represents an 84 percent premium to Vicuron's closing stock price of $15.80 on Wednesday on Nasdaq.

Shares of Vicuron rose 77 percent to $27.99 in pre-market trade on the Inet electronic brokerage.

The transaction gives Pfizer two potentially promising anti-infectives at a time when sales of its anti-fungal treatment Diflucan are plunging following expiration of its U.S. patent last year.

Vicuron, based in King of Prussia, Pa., develops anti-infectives to treat both hospital-based and community-acquired infections. It has two products under review for U.S. marketing approval — anidulafungin (search) for fungal infections and dalbavancin (search) for skin and soft tissue infections.

Both have shown positive results in late-stage studies.

"This transaction builds on Pfizer's extensive experience in anti-infectives," said Hank McKinnell (search), Pfizer's chief executive officer, in a statement.

Dalbavancin is in the same class of drugs as vancomycin, a leading treatment for methicillin-resistant staphylococcus aureus, or MRSA, a hospital-acquired infection that is resistant to the most common antibiotics and has been on the rise since the late 1980s, often leading to death.

Unlike vancomycin, which is usually given either once or multiple times daily through an intravenous line, dalbavancin can be given once a week and may cut out the need for the ongoing use of IV lines in some patients. Vicuron also believes dalbavancin is the most potent treatment in its class.

Vicuron believes that anidulafungin is also more potent than other therapies against the fungi most often responsible for the systemic infections candida and aspergillus and that it is difficult for candida to develop resistance to anidulafungin.

Pfizer launched Diflucan (search) in 1992 followed by Vfend (search), another important antifungal, in 2002.

Pfizer said it believes anidulafungin will represent a significant advance in the treatment of serious fungal infections and that it will complement Vfend.

Pfizer also has an existing research deal with Vicuron to develop next-generation oxazolidinones, the first new class of antibiotics in more than 30 years.

The deal is expected to close in the third quarter of 2005.

Lazard and Cadwalader, Wickersham & Taft LLP advised Pfizer in the transaction, Pfizer said. Morgan Stanley and O'Melveny & Myers LLP advised Vicuron.