Development and pharmacokinetic evaluation of chewable doxycycline tablets in Beagle dogs: comparison with a commercial formulation and evaluation of co-administration with vitamin supplement on the bioavailability

Doxycycline (DOX) is the antibiotic of choice for the treatment of canine monocytic ehrlichiosis (CME), one of the main infectious diseases affecting dogs. Despite the therapeutic simplicity, the need for long-term use of DOX tablets (28 days) and gastrointestinal effects may pose problems. The aim of the study was to develop a DOX chewable tablet, evaluate its palatability and pharmacokinetic profile in comparison with a commercial formulation, Doxifin®, and evaluate the influence of co-administration with vitamin supplement on the bioavailability of doxycycline. The AUC0-t values found for DOX chewable tablets (13.85 ± 3.81 μg.h/mL) and Doxifin® (15.88 ± 4.38 μg.h/mL) did not differ significantly (p<0.05). The co-administration of the vitamin supplement Hemolitan® influenced the pharmacokinetic profile of DOX, leading to a decrease in bioavailability for chewable DOX tablets and Doxifin®, with relative bioavailability values (F) of 64% and 62%, respectively. Palatability evaluations confirmed the palatability of the chewable tablets. Therefore, a DOX chewable tablet is an important alternative that can overcome some of the challenges associated with the characteristic bitter taste of doxycycline, with considerable reduction animal stress, and with plasma doxycycline concentrations equivalent in practical terms to a conventional product.