Optimer Pharmaceuticals Inc., the antibiotics maker that’s weighing a sale, drew interest from drugmakers including GlaxoSmithKline (NYSE: GSK) and Japan’s Astellas Pharma Inc., said two people familiar with the matter.

The maker of the antibiotic Dificid aims to fetch as much as $1 billion in a possible auction, said the people, who asked not to be named because the process is private. Optimer also attracted interest from Cubist Pharmaceuticals Inc. and AstraZeneca Plc, said one of the people.

Buying Optimer would allow the drugmakers to generate more revenue from hospitals, as Dificid, the company’s sole drug on the market, treats a bacterium linked to intestinal infections in hospitalized patients. The drugmaker also may prove attractive to peers that already distribute to medical facilities, because they could use existing distribution channels to reduce costs.

Optimer shares climbed as much as 24 percent following Bloomberg’s report. They advanced to $14.48 at 9:37 a.m. in New York, giving the company a market value of almost $700 million.

Optimer said on Feb. 27 that the board would examine “a full range” of strategic alternatives. The company is working with Centerview Partners LLC and JPMorgan Chase & Co. on the process.

Former Chairman Michael Chang left Optimer last year after the board found that he failed to identify and manage conflict of interest issues tied to a stock grant. The company also replaced Chief Executive Officer Pedro Lichtinger in February, when Optimer disclosed the board’s strategic review.

Representatives for JPMorgan, Astellas, Glaxo, Cubist and AstraZeneca declined to comment. Optimer spokesman David Walsey didn’t return calls seeking comment.

[GSK operates its North American headquarters in RTP.]

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