The manufacturer of Ivomec has hired a research scientist to examine how its popular livestock insecticide stacks up against the generic competition.
Merial has hired Rob Rew of Westchester, Connecticut, to more extensively reproduce a University of Arkansas study that questioned the long-term effectiveness of significantly cheaper generic ivermectin products when compared to more expensive, branded products.
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A story in the May 25 issue, page 73, should have stated that the new study on cattle insecticides, by scientist Rob Rew, is being undertaken on behalf of Pfizer Animal Health. It compares that company’s Dectomax with generic ivermectins, not with Merial’s ivermectin product, Ivomec. Rew’s work follows up on a published University of Arkansas study that compared Ivomec Pour On with generic ivermectins. |
Rew was one of the researchers who helped develop the original ivermectin molecule.
Canadian livestock producers say they have saved as much as 50 percent on their ivermectin bills by importing the generic product from the United States, which can be up to $10,000 per year for larger producers.
Drug makers have lobbied Health Canada to close the border to any generic product that has not been fully tested and approved for sale here.
Farm groups say such a move would keep agricultural drugs that are used in the U.S. out of the Canadian market because of the high cost of testing and licensing.
Rew said the University of Arkansas research showed that generic, pour-on ivermectin was not as effective as its branded counterpart, Ivomec.
The study indicated that the generic product’s effectiveness in controlling parasites was similar to brand name ivermectin 14 and 28 days following application, but by 42 days
Ivomec had a significant advantage. That advantage translated into greater average daily gains on the tested animals.
“It is the average daily gain that I’m really interested in and that is what we’ll be testing in Idaho,” he said.
Rew has contracted an Idaho research feedlot for his study.
Generic product makers usually buy their ivermectin from Chinese manufacturers.
Derived from a bacteria originally found in Japanese soil, Streptomyces avermitilis, the generic drug is imported as a yellowish-white, crystalline powder. In the U.S. it is mixed with alcohol and lightweight oil and bottled at concentrations identical to that of brand name competitors.
“FDA (Food and Drug Administration in the U.S.) would be testing it to ensure that the amount of the molecule was present coming out of those plants,” Rew said. “It’s what happens to it after that I am interested in.”
He said when he worked with the molecule it was subject to damage from inferior oils and alcohols as well as ultraviolet light and oxygen.
“We had to source oil from a cosmetics company and the usual lab-grade alcohol wasn’t pure enough to prevent the breakdown of the molecule,” he said.
Rew and his colleagues used plastics for the bottles from the ketchup industry, another product that is sensitive to oxygen and UV radiation. He thinks the Arkansas results may be reflecting a lack of stability on the part of generic products because manufacturers are saving money on lesser qualities of adjuvants and containers.
“I won’t know until the results are final in the fall. I’m being as independent as I can. I want it to be good science,” he said of the 240 head feedlot study. “I’m pretty sure the Chinese molecule is just fine. FDA inspected that plant and I have no reason to suspect there are any issues there.”
Rew said he fears that the generic drugs may create parasite resistance to ivermectin if they are not used at the full dosage, because of premature breakdown of the molecule.
“The same applies to farmers who don’t store it properly, brand name or not, or who don’t use it exactly as the label requires.”
He said the brand name drug costs more because of the higher priced adjuvants, packaging, testing and marketing.
“This is a very useful compound and we don’t have anything to replace it right now,” he said.
Two manufacturers of generic ivermectin did not respond to requests for interviews.
