Genzyme says FDA will reinspect Allston plant

Shares of Cambridge-based Genzyme tumbled 7.75 percent, or $4.36, to $51.89 on the Nasdaq exchange after the company disclosed that the Food and Drug Administration was concerned that problems the agency had identified last winter had not been “fully or adequately’’ corrected.

The new inspection also will assess the recent shutdown and decontamination of the plant after the virus was found in production equipment there in June. Genzyme this week resumed production in Allston of a pair of biotech drugs for rare genetic disorders.

Genzyme spokesman Bo Piela said the new FDA visit, which has yet to be scheduled, will address two separate but related issues. It is primarily a follow-on to inspections last fall and this spring. But it also will examine steps the company took to sterilize its bioreactors and other equipment during its June and July shutdown to kill the virus, which isn’t harmful to people but could contaminate Genzyme’s biotech drugs.

“Given what’s happened in the last few weeks, it’s only natural the FDA will want to come and take a look,’’ Piela said.

FDA regulators sent Genzyme a warning letter in February identifying deficiencies in its drug-producing equipment and processes uncovered during an inspection last fall. The company took recommended actions to fix the problems before a second inspection in May, Piela said. Some time after that, he said, the FDA gave Genzyme officials verbal assurance they had corrected the plant’s deficiencies.

But this week Genzyme received a letter from the FDA indicating regulators still weren’t completely satisfied with the plant’s maintenance of production equipment and process controls. The plant produces the drugs Cerezyme to treat Gaucher disease and Fabrazyme to treat Fabry disease, both enzyme deficiency disorders.

“We are reinspecting as part of our normal procedures,’’ FDA spokeswoman Karen Riley said in a statement yesterday. “FDA is continuing to actively monitor and investigate the situation taking into full consideration risk mitigation for patients who require these products.’’

The drugs, which cost about $200,000 per patient annually, are used by about 8,000 people around the world. When it temporarily shut the plant, Genzyme drew on its inventory and rationed the drugs for the least vulnerable patients. Piela said its conservation programs will continue until late this year, when it resumes shipping products from batches currently being produced in Allston.

On Wednesday, a Florida stockholder sued Genzyme in US District Court in Boston, alleging the company took too long to alert investors to earlier problems that had been uncovered at its drug production facilities in Allston Landing and Belgium.

Piela said Genzyme works “to provide our investors with timely and appropriate information’’ about its business. “We’re confident in the way we’re managing our communications,’’ he said.

Robert Weisman can be reached at weisman@globe.com.