Shares of Optimer Pharmaceuticals
Inc. rose in pre-market trading today after a government panel recommended
approval of Optimer’s antibiotic Dificid.

On Tuesday, an FDA panel
recommended approval for Dificid, which is intended to treat Clostridium
difficile, a bacterium that can cause diarrhea and dangerous inflammation of
the colon.

Shares rose 25 cents, or 1.8
percent, to $14.05 in pre-market trading. Optimer shares have traded between
$7.68 and $16.30 in the last year.

Jefferies & Co. analyst Eun
Yang said it’s not a guarantee the FDA will approve the drug on May 30. The
panel found Dificid was safe and effective, and panelists voted that it was
more effective than the drug Vancocin in preventing recurrent infections. But
she said the FDA and Optimer may need to hold discussions about the drug’s
label and how it will reflect information about recurrent infections.

Yang said she is conservatively
assuming Dificid will reach the market in the fourth quarter. She kept a
“Buy” rating on Optimer shares, and said she expects worldwide sales
of Dificid to reach $240 million in 2015. She said Optimer should become
profitable in 2014.