ProHeart6 Injectable Heartworm Prevention Recalled by the FDA

At 4:30 PM on the Friday before Labor Day weekend, the Food and Drug Administration issued a press release that Fort Dodge Animal Health had agreed to a voluntary recall of their popular heartworm prevention product, Proheart6. Proheart6 is an injectable product which prevents both heartworm  and hookworm infection. One dose lasts six months thus enabling a dog to come to the vet’s office once a year in the Spring and have its examination, vaccinations, and heartworm prevention for the season all at once.  Here in Los Angeles, where mosquito season varies tremendously with rainfall and heartworm is a small concern, Proheart6 serves mostly to protect traveling dogs.  Owners were free to bring their dogs into heartworm-rich areas anytime they wanted to during the six month period without remembering to give pills or topicals for prevention.

So what went wrong?

The FDA requires that drugs be demonstrated to be “safe and effective.” This is typically done using studies involving several hundred patients at substantial cost to the drug manufacturer. When the drug is released it will then be used on several thousand patients and as a result less common reactions may emerge.  The FDA collects reports of such reactions and they must be included on revised versions of the product insert as the “post release experience.” How does the FDA know which reports are really reactions to the drug and which are coincidence? They don’t.  In the case of Proheart6 any symptom occurring during the six month duration of the injection could be reported as a potential “adverse drug event.” Reactions can be reported by anyone over the internet.  The newness of internet reporting and the unusually long activity of a single dose of Proheart6 makes it uniquely difficult to sort out real drug reactions for coincidence.

Between June 2001 when it was released and August 4th, 2004 the FDA received a total of 5,552 reaction reports, an unusually large amount but hard to interpret in light of the long activity of the product.  The FDA’s mission is to protect the public and these reports cannot be ignored. What do these reports mean and how many are really drug reactions? The FDA has called for an independent research group to sort these reports out and until they are finished Proheart6 will be unavailable for use.

For more details see: www.veterinarypartner.com/Content.plx?P=A&A=1721

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