Study finds emodepside formulations in dogs are not bioequivalent
A new pharmacokinetic study is sharpening an important clinical point for veterinarians using emodepside against multianthelmintic drug-resistant canine hookworms: formulation matters. Researchers from Kansas State University and Utah State University reported that the FDA-approved feline topical emodepside product, when given orally to dogs, was not bioequivalent to the European canine oral modified-release tablet, the formulation that has shown efficacy against resistant Ancylostoma caninum. In the seven-dog crossover study, plasma concentrations after topical administration were 36- to 122-fold lower than after oral administration. The study also found that when the feline topical product was given orally at 1 mg/kg, it produced higher, not matching, systemic exposure versus the canine tablet at the same dose, with about a threefold higher peak concentration and 2.4- to 2.8-fold greater total exposure—still failing bioequivalence standards. (pubmed.ncbi.nlm.nih.gov)
Why it matters: For veterinary professionals, the study adds evidence that extra-label oral use of a feline topical product in dogs shouldn't be treated as interchangeable with the canine oral formulation simply because the active ingredient is the same. That matters in a setting where emodepside has emerged as a last-line option for suspected or confirmed multidrug-resistant hookworm infections, but where dosing precision, MDR1 risk, heartworm status, and AMDUCA compliance are all critical. The AVMA’s Veterinary Vertex discussion of the paper underscored the same takeaway: route and formulation materially change the rate and extent of absorption. Clinical guidance from parasitology experts has already cautioned that excipients in topical products aren't designed for oral use and can change pharmacokinetics and safety. (cliniciansbrief.com)
What to watch: Expect this paper to influence how clinicians discuss extra-label emodepside use, and whether future U.S. access to a canine oral formulation becomes a bigger regulatory and clinical priority. It also adds context around emodepside itself as an octadepsipeptide anthelmintic with a different mechanism of action from other marketed dewormer classes—part of why it has drawn attention in resistant hookworm cases. (pubmed.ncbi.nlm.nih.gov)