Washington ? An antibiotic linked to a growing number of reports of liver failure, including four deaths, should bear stricter warnings about its effect on the liver, according to an internal Food and Drug Administration memo. The drug’s manufacturer, Sanofi-Aventis, said Friday it was in talks with FDA officials about those reports.

The FDA has received reports of 12 cases of acute liver failure, including the four deaths, in patients treated with Ketek, according to the memo. FDA safety evaluators also uncovered 23 other cases where patients suffered serious liver injuries after receiving the antibiotic, which is formally called telithromycin.

When considered in proportion to the number of prescriptions filled for Ketek, the reports exceed what’s been seen in similar antibiotics, the memo said.