Because of limited supplies, veterinarians will have to buy a treatment for canine heartworm disease directly from the manufacturer.
Dr. Zack Mills, vice president of sales for Merial, wrote in a Dec. 1, 2009, letter to veterinarians that unforeseen technical difficulties during a planned manufacturing site transfer led to limitations in the supply of Immiticide for the first quarter of 2010.
"We believe that by careful management of existing product, we should be able to meet the needs of most veterinary practices for treatment of heartworm disease in their patients," the letter states.
Natasha Joseph, a Merial spokeswoman, further explained that the supply limitations are related to regulatory requirements at a facility that manufactures the drug's active ingredient, but she declined to provide additional details about the regulatory issues. Merial is managing supplies for cases for which there is an urgent need, and the company is working diligently to return to full supply.
"Each request for Immiticide is discussed on a case-by-case basis, veterinarian to veterinarian, to evaluate the overall health of the dog, disease classification, absence or presence of clinical signs, and other criteria," Joseph said.
Immiticide is one of two drugs approved by the Food and Drug Administration for treatment of heartworm disease in dogs, but the older of the two drugs, Caparsolate Sodium, is not currently manufactured or marketed in the United States, according to the FDA.
Dr. Sheldon B. Rubin, president of the American Heartworm Society, said, as a practitioner, he thinks the shortage will be an inconvenience but not a serious problem. He believes enough of the drug will be available for dogs with clinical signs of heartworm disease, whereas dogs that test positive but do not have clinical signs can remain on monthly prophylaxis until more doses of the drug are available.
The American Heartworm Society is sure Merial is doing everything possible to supply enough of the product to meet demand, Dr. Rubin said.
"We've had shortages of other drugs before and limited supplies and drugs pulled off the market, and we always seem to get around it," Dr. Rubin said. "And I think we'll be able to get through this, too."
Dr. Charles A. Lemme, who represents the American Animal Hospital Association on the AVMA Clinical Practitioners Advisory Committee, said a shortage could have a substantial impact. But it appears to him that Merial is trying to prevent such a shortage by discouraging the stockpiling of drugs that could go unused.
"Hopefully, there won't be enough of a shortage that we'll have to alter our medical protocols," Dr. Lemme said. "I think what they're really looking for is to alter our buying habits."
Merial is asking that veterinarians order Immiticide as necessary by calling 888-Merial1 (888-637-4251) and selecting option 1.