Updated

Pfizer said Thursday it is recalling intravenous drugs with floating matter in them, warning they could potentially kill weakened patients, after U.S. regulators warned about the worries earlier this week.

The products — made by Claris Lifesciences and distributed in the U.S. by Pfizer — are the antibiotics metronidazole and ciprofloxacin and a drug used to prevent nausea and vomiting caused by surgery and chemotherapy, named ondansetron.

The Food and Drug Administration (FDA) on Sunday warned doctors and hospitals not to use them because of worries the floating matter meant the products weren't sterile.

Thursday, Pfizer said non-sterility in intravenous drugs could be fatal for patients with weakened immune systems. In addition to the company's voluntary recall, it is halting its distribution of all sterile injectable products and IV bags licensed from Claris.

Shares in Pfizer were down 0.9 percent at $15.10 in after-hours trading. The stock is roughly flat on the year, underperforming the market at large.

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