Study warns emodepside formulation changes exposure in dogs

CURRENT BRIEF VERSION: A new AJVR study is sharpening an important point for veterinarians using emodepside against multidrug-resistant canine hookworms: formulation matters. Researchers at Kansas State University and collaborators found that the FDA-approved feline topical emodepside/praziquantel product, when given orally to dogs at 1 mg/kg, was not bioequivalent to the European canine modified-release oral tablet at the same dose. In seven healthy client-owned dogs, oral dosing of the feline topical product produced markedly higher emodepside absorption than the canine tablet, with peak plasma concentrations about 3 times higher and overall systemic exposure about 2.4- to 2.8-fold greater. Meanwhile, topical administration of the feline product produced plasma concentrations 36- to 122-fold lower than oral dosing. The paper concludes that the feline topical formulation, whether used orally or topically in dogs, should not be assumed to perform like the canine oral product. (pubmed.ncbi.nlm.nih.gov)

Why it matters: For veterinary professionals, this is a practical safety and prescribing story, not just a pharmacokinetics story. Emodepside has emerged as a last-line option for multi-anthelmintic drug-resistant Ancylostoma caninum, a problem now reported beyond greyhounds and across the U.S. and into Canada. The AVMA’s Veterinary Vertex podcast accompanying the paper also emphasized the broader takeaway: route and formulation really matter, and “same mg/kg” does not mean the same rate and extent of drug exposure. That suggests extra-label oral use of the cat topical product may expose dogs to substantially different systemic drug levels than the oral canine formulation used in prior efficacy work, raising safety concerns and reinforcing the need for careful case selection, informed consent, and screening for risks such as heartworm infection and MDR1-related susceptibility before treatment. (pubmed.ncbi.nlm.nih.gov)

What to watch: Expect this study to influence how parasitologists, internists, and general practitioners discuss dosing protocols, safety screening, and future U.S. research on emodepside for resistant hookworm cases. It also adds context for U.S. clinicians working without access to the canine European product and relying instead on a feline topical formulation with very different pharmacokinetic behavior. (pubmed.ncbi.nlm.nih.gov)