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SummaryPavlova, I., 2015. Effect of probiotics on doxycycline disposition in gastro-intestinal tract of poultry. Bulg. J. Vet. Med., 18, No 3,[248][249][250][251][252][253][254][255][256][257] Poultry feed is often supplemented with probiotics in order to improve disease resistance and growth performance and to decrease undesirable effects of antibacterial therapy. Therefore this study was designed to evaluate the effect of probiotics such as Lactobacillus brevis, L. plantarum and L. bulgaricus on pharmacokinetics of doxycycline in healthy DUC broiler chickens. The treatment with doxycycline at a dose of 10 mg/kg body weight started on the 15 th day after hatching for 5 days via drinking water. The probiotics treated group received Lactobacillus strains for 15 days, 5 days after hatching. Treatment with probiotics did not lead to statistically significant differences in serum concentrations of doxycycline between both groups of chickens. The value of C max was significantly higher in the liver of doxycycline + probiotics treated chickens (0.23±0.1 µg/g) than in doxycycline-treated group (0.19±0.17 µg/g). The same tendency was observed in the jejunum of both groups of animals suggesting favourable results in the cure of bacterial diseases of the gastrointestinal tract of poultry.The selected dose was appropriate for treatment of infections caused by pathogens with MIC < 0.25 µg/mL irrespective of antibiotic administration alone or in combination with probiotics. The simultaneous treatment of chickens with probiotics and doxycycline did not entail changes in the dose regime of the antibiotic.

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Macedonian Veterinary ReviewThe pharmacokinetics of doxycycline was investigated in force-fed and normally fed ducks after single intravenous (i.v.) and oral (p.o.) administration at a dose of 15 mg/kg bw. Serum concentrations of the drug were determined by the HPLC method. Pharmacokinetic parameters were calculated using compartmental analysis. Serum concentrations of doxycycline after i.v. administration in both groups were not statistically different. The values of half-lives were 5.82±1.85 h and 6.06±5.51 h in normal and force-fed birds. The total body clearance was respectively 0.40±0.05 L/h/kg and 0.34±0.10 L/h/kg, and volume of distribution (V ss ) was 2.80±0.85 L/kg and 2.18±0.89 L/kg. After p.o. administraton the maximum serum levels in the control group were 0.70±0.12 μg/mL and in force-fed birds were 1.93±0.32 μg/mL, measured at 2.95±0.60 h and 1.45±0.24 h, respectively. The values of absolute bioavailability were 18.89±6.48% and 37.58±13.63%. Longer doxycycline retention in force-fed ducks was registered. Our data can be accepted as an information for possible prolonged retention of doxycycline in force fed ducks compared to normally fed ones.

Probiotics are routinely used in poultry husbandry due to health benefit on the host. The gut microbiota is now recognized to exert an important influence on the absorption and pharmacokinetics of many compounds. Therefore, this study was designed to evaluate the effect of candidate probiotics belonging to the species Lactobacillus brevis, L. plantarum and L. bulgaricus on pharmacokinetics of enrofloxacin in healthy chickens. The probiotic administration leads to higher degree of metabolism of enrofloxacin to ciprofloxacin in liver. The antibacterial drug was significantly faster absorbed (kab of 0.61 ± 0.54 h(-1) and Tmax 7.81 ± 3.52 h) at lower concentrations (Cmax of 1.34 ± 0.18 μg·g(-1)) during the first 24 h of treatment in the probiotic's group. The values of kab , Tmax , and Cmax for the group, treated solely with enrofloxacin, were 0.10 ± 0.065 h(-1), 15.42 ± 3.07 h, and 1.61 ± 0.24 μg·g(-1), respectively. A significantly higher concentration of enrofloxacin and its metabolite ciprofloxacin in the liver was observed in the group with the probiotic treatment. Disposition of both drugs was not significantly changed in the duodenum and in the jejunum. The selected dose is appropriate for treatment of infections caused by pathogens with MIC < 0.06 μg·mL(-1) irrespective of antibiotic administration alone or in combination with probiotics.

Expression of peptide transporter 1 (PepT1) and liver-expressed antimicrobial peptide 2 (LEAP-2) in chickens can be influenced by food deprivation, pathological conditions and drug administration. Effect of three putative probiotic Lactobacillus strains and enrofloxacin on the expression of PepT1 and LEAP-2 mRNA was investigated in Ross 308 chickens. One-day-old chicks (n = 24) were allocated to following groups: control (without treatment); group treated with probiotics via feed; group treated with a combination of probiotics and enrofloxacin; and a group given enrofloxacin only. The drug was administered at a dose of 10 mg kg, via drinking water for 5 days. Samples from liver, duodenum and jejunum were collected 126 h after the start of the treatment. Expression levels of PepT1 and LEAP-2 were determined by real-time polymerase chain reaction and were statistically evaluated by Mann-Whitney test. Enrofloxacin administered alone or in combination with probiotics provoked a statistically significant up-regulation of PepT1 mRNA levels in the measured organ sites. These changes can be attributed to a tendency of improvement in utilization of dietary peptide and in body weight gain. LEAP-2 mRNA expression levels did not change significantly in enrofloxacin-treated chickens in comparison with control group.

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