Distribution of Flumequine in Intestinal Contents and Colon Tissue in Pigs after Its Therapeutic Use in the Drinking Water

SIMPLE SUMMARY: Gastrointestinal diseases are relatively common in pigs, and cause important economic losses. These disorders include, among others, swine dysentery, a severe diarrheal disease in growing and finisher pigs caused by Brachyspira hyodysenteriae. Flumequine, a fluoroquinolone indicated in the treatment of colibacillosis, enteritis and gastroenteritis, may help to minimize the impact of swine dysentery. Thus, the objective of this study was to assess flumequine concentrations in pig plasma, colon tissue and intestinal contents following oral administration through drinking water, and determine if it would be effective against the sensitive bacteria found in the colon. The drug was not detected in any plasma sample, while concentrations were higher on the days of treatment than after having finished it. Concentrations achieved in colon tissue and intestinal contents were lower than those effective against the most common intestinal pathogenic microorganisms in swine, including B. hyodysenteriae, suggesting that this dosage would not be effective. ABSTRACT: Flumequine concentrations in plasma, colon tissue and intestinal contents were evaluated in 12 healthy pigs after oral administration (12 mg/kg every 24 h for 5 consecutive days in drinking water). Plasma, colon tissue and intestinal content samples were collected from animals sacrificed on days 3, 6 and 7. Concentrations were measured by high performance liquid chromatography after having validated the method, following the European Medicines Agency (EMA) requirements. The drug was not detected in any plasma sample. In colon tissue, concentrations were higher on day 3 (0.230 ± 0.033 µg/g, descending colon; 0.156 ± 0.093 µg/g, ascending colon) than on day 6 (0.187 ± 0.123 µg/g, descending colon; 0.107 ± 0.007 µg/g, ascending colon). Concentrations were considerably higher in intestinal contents, again on day 3 (1.349 ± 1.401 µg/g, descending colon; 0.591 ± 0.209 µg/g, ascending colon) than on days 6 (0.979 ± 0.346 µg/g, descending colon; 0.595 ± 0.075 µg/g, ascending colon) and 7 (0.247 ± 0.172 µg/g, descending colon; 0.172 ± 0.086 µg/g, ascending colon). Measured concentrations were lower than those effective against the most common intestinal pathogenic microorganisms in swine and, more specifically, Brachyspira hyodysenteriae.