Safety of mycotoxin binders in broiler feed: interaction with the oral absorption of veterinary drugs and coccidiostats

Mixing mycotoxin binders in animal feed is nowadays the most commonly used method to prevent damage caused by mycotoxins. Mycotoxin binders aim to adsorb the toxin to their surface in the gastro-intestinal tract of the animal, thereby preventing the systemic uptake of the mycotoxin. The adsorption mechanisms are deemed to be non-specific and in 2010 EFSA stated that their safety, in terms of non-specific binding, should be investigated. The aim of this project is to investigate possible interactions of mycotoxin binders with the oral absorption of frequently used veterinary drugs and coccidiostats in broiler chickens. First, the in vitro adsorption of sulfadiazine (SDZ), trimethoprim (TRIM), tylosin (TYL), doxycycline (DOX)1, diclazuril (DICL), lasalocid (LAS) and salinomycin (SAL) to 6 different mycotoxin binders and active carbon was assessed in a single-concentration adsorption screening assay. Next, two in vivo experiments were executed in broiler chickens with 2 selected clay-based binders and active carbon. Pharmacokinetic profiles were constructed for SDZ + TRIM and DOX1 in broilers that received a single oral bolus containing the daily dose of either drug, or the combination of binder and drug. A third experiment assessed the oral absorption of TYL, DOX, SAL and DICL after a 2-week exposure period to the binder. Several binder-drug combinations showed over 90% in vitro adsorption for TRIM, DOX, DICL, LAS or SAL. Results of the first two in vivo experiments demonstrated a significant interaction of 2 clay-based binders and DOX, since these binders were able to lower the oral bioavailability of DOX to less than 40% compared to broilers receiving only DOX. No interactions of these binders with SDZ + TRIM were seen. Results of the third in vivo experiment will be presented on the workshop