In vitro adsorption and in vivo pharmacokinetic interaction between doxycycline and frequently used mycotoxin binders in broiler chickens

Mycotoxin binders are readily mixed in the feed to prevent uptake of mycotoxins by the animal. Concerns were raised for non-specific binding with orally administered veterinary drugs by the European Food Safety Authority in 2010. This paper describes the screening for in vitro adsorption of doxycycline - a broad spectrum tetracycline antibiotic - to six different binders that were able to bind more than 75% of the doxycycline. Next, an in vivo pharmacokinetic interaction study of doxycycline with two of the binders, which demonstrated significant in vitro binding, was performed in broiler chickens using an oral bolus model. It was shown that two montmorillonite based binders were able to lower the area under the plasma concentration-time curve of doxycycline with more than 60% compared to the control group. These results may indicate a possible risk for reduced efficacy of doxycycline when used concomitantly with montmorillonite based mycotoxin binders