WASHINGTON (Reuters) - Wyeth's Proheart 6 heartworm prevention drug for dogs is returning to the U.S. market with restrictions four years after reports of sometimes deadly reactions led to its recall, U.S. officials said Thursday.
The Food and Drug Administration said the company had made manufacturing changes to reduce such complications, but the move still raised questions over why the drug was being sold again.
Wyeth voluntarily recalled the injectable drug in 2004 amid thousands of reports of dogs that had serious and sometimes fatal reactions.
Some dogs given Proheart 6 injections before the recall experienced loss of appetite, lethargy, vomiting, seizures, difficulty walking and jaundice, as well as bleeding disorders, allergies and convulsions, the FDA said.
As many as 485 dog deaths may have been linked to Proheart 6, FDA officials said at a public meeting in 2005. Wyeth officials said Thursday they could not estimate how many fatalities may have been linked to the drug, saying there could have been other causes.
On Thursday, the company said distribution of Proheart 6 will be limited to veterinarians who register with the manufacturer and complete a Web-based training program. Pet owners will be asked to sign consent forms.
"While we concur with the limited return of ProHeart 6 to the U.S. market, we strongly encourage veterinarians and pet owners to report any possible adverse reactions," Bernadette Dunham, director of the FDA's Center for Veterinary Medicine, said in a statement.
Sen. Charles Grassley, an Iowa Republican who has been critical of the FDA's oversight of drug safety and has been investigating circumstances surrounding Proheart 6, immediately questioned the decision.
In a letter to FDA Commissioner Andrew von Eschenbach, Grassley asked whether agency safety experts had been involved inmore than 18 meetings and 85 phone calls between the agency and Wyeth's unit to discuss the drug.
Grassley has said his investigation found the FDA scientist who uncovered the link between Proheart 6 use and canine deaths, Victoria Hampshire, was forced from her job at Wyeth's urging. He had requested more information from the agency earlier this year, but said Thursday the FDA never responded.
Representatives for the FDA had no immediate comment on Grassley's letter.
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