Background Metformin hydrochloride is a biguanide derivative that has been widely used to treat type 2 diabetes in humans. In veterinary medicine, metformin has shown increasing potential for diabetes treatment in different species, such as equids, dogs, cats and rabbits. It is highly hydrophilic, with incomplete gastrointestinal absorption and very large variability in absolute bioavailability between species, ranging from 4% in equids to 60% in humans. Metformin also shows a short half-life of approximately 2 h in dogs, cats, horses and humans. The objectives of this study were to evaluate a poly (lactic acid) (PLA) metformin microparticle formulation to test in rabbits and conduct a pharmacokinetics study of intravenous (SIV) and oral solution (SPO) metformin administration and oral PLA microparticle (SPLA) administration to rabbits to evaluate the improvement in the metformin pharmacokinetics profile. Results Metformin-loaded PLA microparticles were characterized by a spherical shape and high encapsulation efficiency. The results from Fourier transform infrared (FTIR) spectroscopy suggested the presence of interactions between metformin and PLA. X-Ray diffraction (XRD) analysis corroborated the results from the differential scanning calorimetry (DSC) studies, showing that metformin is present in an amorphous state within the microparticles. Physicochemical characterization suggested that PLA and metformin hydrochloride interacted within the microparticles via hydrogen bonding interactions. The pharmacokinetic study in rabbits showed sustained-release characteristics from the prepared microparticles with a delay in the time needed to reach the maximum concentration (Tmax), decreased Cmax and bioavailability, and increased mean residence time (MRT) and half-life compared to the pure drug solution. Conclusions Metformin-loaded PLA microparticles showed optimal and beneficial properties in terms of their physicochemical characteristics, making them suitable for use in an in vivo pharmacokinetic study. The pharmacokinetic parameters of the metformin microparticles from the in vivo study showed a shorter Tmax, longer MRT and half-life, decreased Cmax and the prolonged/sustained release expected for metformin. However, the unexpected decrease in bioavailability of metformin from the microparticles with respect to the oral solution should be evaluated for microparticle and dose design in future works, especially before being tested in other animal species in veterinary medicine.

BackgroundBacterial pneumonia in goats is usually caused by Mannheimia haemolytica and Pasteurella multocida. Another important infection disease in lactating goats is intramammary infection producing mastitis, usually associated with coagulase-negative Staphylococcus spp. However, treatment of bacterial pneumonia in goats not affected by mastitis problems should be restricted to antimicrobials with scant penetration to milk in order to avoid long withdrawal times. Ceftiofur is a third-generation cephalosporin antimicrobial with activity against various gram-positive and gram-negative, aerobic and anaerobic bacteria encountered by domestic animals. The objectives of the present study were to establish the serum concentration–time profile for ceftiofur in lactating goats after intravenous, subcutaneous and a SC-long-acting ceftiofur formulation; to determine ceftiofur penetration into milk; to determine in vitro and ex vivo activity of ceftiofur establishing MIC, MBC, MPC and time-kill profiles against field strains of M. haemolytica and finally to calculate the main surrogate markers of efficacy.ResultsThe pharmacokinetics studies revealed an optimal PK properties for the SC-LA formulation tested. Ceftiofur was well absorbed following SC and SC-LA administration, with absolute bioavailabilities (F) of 85.16 and 84.43 %, respectively. After ceftiofur analysis from milk samples, no concentrations were found at any sampling time. The MIC, MBC and MPC data of ceftiofur against five M. haemolytica strains isolated from goats affected by pneumonia were tested showing excelent sensitivity of ceftiofur against this pathogen. For PK-PD analysis, ratios were calculated suggesting a high level of bacterial kill against the five strains of M. haemolytica tested.ConclusionsThe systemic ceftiofur exposure achieved in lactating goats following IV, SC and especially with the SC-LA administration is consistent with the predicted PK-PD ratios needed for a positive therapeutic outcome for M. haemolytica. Subcutaneous administration of the long-acting formulation showed safety and tolerance for all the animals used. Ceftiofur concentrations exceeded the MIC and MBC for up to 72 h and MPC for up 32 h in serum. Thus, this drug could be effective in treating infectious diseases of goats caused by M. haemolytica at a dose of 6 mg/kg with the SC-LA formulation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-016-0863-9) contains supplementary material, which is available to authorized users.

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Minimum inhibitory concentration (MIC) and mutant prevention concentration (MPC) of veterinary fluoroquinolones as enrofloxacin, its metabolite ciprofloxacin, danofloxacin, difloxacin and marbofloxacin against strains (n=24) isolated from milk of sheep and goats affected by clinical mastitis were evaluated. The authors have used the MIC and MPC, as well as the pharmacokinetic-pharmacodynamic relationships in plasma and milk. MIC values were significantly different between drugs, unlike MPC values. Lower MIC values were obtained for danofloxacin and difloxacin, middle and higher values for enrofloxacin, ciprofloxacin and marbofloxacin. However, differences in MPC values were not found between drugs. At conventional doses, the AUC/MIC and AUC/MPC ratios were close to 30-80 hours and 5-30 hours, with exception of danofloxacin, in plasma and milk. The time inside the mutant selection window (T) was close to 3-6 hours for enrofloxacin, ciprofloxacin and marbofloxacin, near to 8 hours for danofloxacin and 12-22 hours for difloxacin. From these data, the mutant selection window could be higher for danofloxacin and difloxacin compared with the other fluoroquinolones tested. The authors concluded that enrofloxacin and marbofloxacin, at conventional doses, could prevent the selection of bacterial subpopulations of , unlike danofloxacin and difloxacin, where higher doses could be used.

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Triple intrathecal standardized preparations of methotrexate, cytarabine, and hydrocortisone sodium phosphate are physically and chemically stable at 25℃ for 48 h and at 2-8℃ for 5 days.

Background: Metformin hydrochloride a biguanide derivative has been widely used in the treatment of type 2 diabetes in humans. In veterinary medicine, metformin has been increasing his potential in different species as equids for insulin dysregulation, dogs and cats with diabetes. It is a highly soluble hydrophilic drug, shows incomplete absorption from the gastrointestinal tract and the absolute bioavailability is 40-60 % with a short biological half-life of 1.5-1.6 h in humans. In this study, to improve its efficacy a sustained-release microparticles of metformin was developed by loading within poly lactic acid (PLA) polymer followed by an in vivo pharmacokinetics study in rabbits. Results: Pharmacokinetic study in rabbits showed the sustained-release characteristic from the prepared microparticles with delayed time to reach maximum concentrations Tmax, decreased Cmax, increased Mean Residence Time (MRT) and half-life compared to the pure drug solution. Physicochemical characterization suggested that PLA and metformin hydrochloride interacted within the microparticles via hydrogen bonds and that the drug was transformed to an amorphous state. Conclusions: The The pharmacokinetics parameters resulted in delayed Tmax, increased MRT and t1/2, decreased Cmax of metformin from microparticles that show promise for prolonged/sustained release of metformin after oral administration in different animal species affected by insulin disorders. PLA microparticles provided sustained release of the drug, and these systems can be useful as drug carriers for hydrophilic drugs in long term disease treatment such as diabetes.