Baxter International Inc. said Thursday that it had recalled the remaining lots of its troubled blood-thinning drug heparin as U.S. regulators reported "objectionable conditions" at the Chinese factory that supplied the raw ingredient for the drug.
Heparin has been linked to four deaths and hundreds of adverse reactions and is the subject of an investigation by the Food and Drug Administration.
It is not known whether the Chinese plant is the cause of the problems, the FDA said.
"It's like trying to put together pieces of a puzzle," said Sandra Kweder, deputy director of the agency's Office of New Drugs. "So far, an underlying cause of the adverse events is not known and it remains under investigation."
The comments were the first describing the FDA's investigation of the Chinese plant. The agency has admitted that it failed to inspect the facility before approving it because it confused the company's name with that of another.
The FDA said the plant had problems with "waste material flow," "process validation" and equipment flaws, but it did not elaborate.
The FDA team in China consists of two people, one of whom speaks fluent Chinese. Officials said they were investigating other Chinese facilities, workshops and farms that may have been involved in the manufacturing chain.
Baxter initially halted nine lots of heparin in January and expanded the recalls earlier this month.
In addition to the four deaths, adverse reactions included difficulty breathing, vomiting and very low blood pressure in patients taking the drug.
Heparin is made from pig intestines and is used in dialysis and heart procedures to avoid blood clots in veins, arteries and lungs.
The FDA said 448 adverse events had been reported, though Kweder said only 215 were "events of interest." In addition to the four deaths already believed to be linked to the drug, the deaths of 21 other patients taking heparin have been reported to the FDA.
The company expanded its voluntary recall after regulators concluded there was enough capacity from other suppliers.
APP Pharmaceuticals Inc. has been able to ramp up production to avoid a drug shortage, the FDA said.
The factory used by Baxter and inspected by the FDA is located in Changzhou, China. It is owned by Scientific Protein Laboratories in Wisconsin.
Scientific Protein Labs said in a statement that it was cooperating with the FDA and preparing a response. It noted that no root cause of the problems had been determined.
Baxter said its recall did not include heparin premixed intravenous solutions in bags, which are supplied by a different company.
Separately, and unrelated to its heparin woes, Baxter has agreed to pay a $15,000 fine for inadequately testing irradiation equipment at a plant in Puerto Rico.
The Nuclear Regulatory Commission said Thursday that its inspectors had uncovered at least three violations last March at a plant in Aibonito, Puerto Rico.
The Associated Press was used in compiling this report.