Wyeth dog drug not proven safe - US FDA panel

Wyeth failed to convince a U.S. advisory panel on Monday that a heartworm prevention drug that regulators link to hundreds of dog deaths is safe enough to return to the U.S. market.

Wyeth failed to convince a U.S. advisory panel on Monday that a heartworm prevention drug that regulators link to hundreds of dog deaths is safe enough to return to the U.S. market.

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A Food and Drug Administration advisory panel voted 8-7 that more information needs to be collected on the drug, an injection called Proheart 6.

A majority of members said they were not yet convinced the drug's risks were small and outweighed by the benefit of preventing heartworm for six months, as Wyeth contends. Other heartworm prevention drugs need to be given monthly.

"At this point, we still need some additional data to say this is safe. I think the voluntary recall should continue for the time being," panel member Gregory Jaffe said.

Wyeth voluntarily withdrew Proheart 6 from the U.S. market last September amid thousands of reports of serious side effects, including 600 dog deaths.

The FDA said 485 of the deaths may have been linked to Proheart 6, which was approved for sale in June 2001. The agency also received reports of possible reactions such as seizures and liver damage in more than 5,000 dogs.

Many problems appeared within hours of Proheart injections.

Wyeth disagreed that Proheart 6 caused that many serious problems, arguing vaccines given at the same time to many of the dogs could have been the culprit.

The company said the drug was no more dangerous than two other heartworm prevention medicines on the market and had been given to an estimated 12 million dogs.

"We're disappointed in the vote, and we're going to work with the FDA to resolve the outstanding issues," Wyeth spokeswoman Natalie de Vane said.

The company continues to sell the drug in eight other countries, including Japan and Australia. Regulators in all eight countries have reviewed the Proheart data and found no cause for alarm, de Vane said.

Wyeth declined to provide sales figures for Proheart 6, but the company had highlighted the drug as one of its biggest products in its Fort Dodge Animal Health division. The bulk of Wyeth's sales come from drugs for people.

The FDA will consider the panel's ruling as it decides whether to tell Wyeth to resume sales of Proheart 6. The agency usually follows recommendations from its advisory panels.

Heartworm is a serious but preventable parasitic disease transmitted by mosquitoes. The infection primarily affects dogs and cats. It can be treated, but there is a risk that worms can break lose during therapy and cause deadly blood clots.

Arthur Craigmill, the advisory panel chairman, said he was moved by testimony and letters from distraught pet owners whose dogs had died after Proheart shots.

"Having lost pets of my own, I can relate to them," he said, but added he felt the drug's risks were "acceptable" and it should be sold again.