Cats with MDR1 mutation at risk of reactions to medication

While the ingredient, eprinomectin, appears safe and effective for the significant majority of cats when used at label doses, a study conducted by Washington State University’s Program for Individualized Medicine identified a risk of severe adverse effects in cats with the MDR1 genetic mutation. Genetically affected cats lack a protective mechanism that prevents certain drugs, including eprinomectin, from entering the brain and causing serious neurological toxicity.