Pharmacokinetics of minocycline in crucian carp (Carassius auratus ) after intravenous and oral administration

The Pharmacokinetics of Doxycycline in Channel Catfish (Ictalurus punctatus) Following Intravenous and Oral Administrations

The objective of this study was to investigate the bioavailability (BA) and pharmacokinetics (PK) of doxycycline (DC) in channel catfish (Ictalurus punctatus) following a single intravenous injection at 5 mg/kg and a single oral administration at 50 mg/kg at 24°C. The calculation of PK parameters was based on the software 3P97. The plasma samples were determined using ultra-performance liquid chromatography. Following oral administration, the multiple-peak phenomenon presented in concentration vs. time curve of DC at 2 h (107.01 mg/L), 8 h (55.07 mg/L), and 72 h (15.10 mg/L), respectively. The compartmental model cannot simulate the oral concentration vs. time profile beside a non-compartmental model. The calculated parameters of the elimination rate constant (λ_z), the elimination half-life (t_1/2λz ), and the area under the concentration vs. time curve (AUC_0-144) were 0.037 1/h, 18.91 h, and 2255.45 μg.h/mL, respectively. After intravenous administration, the concentration vs. time profile of DC was best described by a two-compartmental open model without absorption. The parameters of the distribution rate constant (α), the distribution half-life (t_1/2α), the elimination rate constant (β), the elimination half-life (t_1/2β), the apparent distribution volume at steady state (V_ss), the total clearance (Cl) and the area under the concentration vs. time curve (AUC_0-∞) were 2.79 1/h, 0.25 h, 0.042 1/h, 16.51 h, 300.00 mL/kg, 14.00 mL/h/kg, and 364.99 μg.h/mL, respectively. For the calculation of BA values at the same condition, the data obtained from intravenous injection were also iterated based on a non-compartmental model, and the corresponding parameters of λ_z, t_1/2λz , V_z, Cl, and AUC_0-144 were 0.019 1/h, 36.26 h, 480.00 mL/kg, 9.10 mL/h/kg, and 514.45 μg.h/mL, respectively. However, there was a considerable difference in the same parameter when calculated by compartmental and non-compartmental approaches. Finally, the medium BA value of DC was evaluated to be 43.84%. This study provides future studies with a framework for determining the BA of DC in the development of a new formulation and provides information on the appropriate use of DC in aquaculture.

Sulfadiazine pharmacokinetics in grass carp (Ctenopharyngodon idellus) receiving oral and intravenous administrations

This study aimed to examine the bioavailability (BA) and pharmacokinetic (PK) characteristics of sulfadiazine (SDZ) in grass carp (Ctenopharyngodon idellus) after oral and intravenous administrations. Blood samples were collected at predetermined time points of 0.083, 0.17, 0.5, 1, 2, 4, 8, 16, 24, 48, 72, and 96 hr (n = 6). The samples were extracted and purified by organic reagents and determined by the ultra-performance liquid chromatography. The software named 3P97 was used to calculate relevant PK parameters. The results demonstrated that the concentration-time profile of SDZ was best described by a one-compartmental open model with first-order absorption after a single oral dose. The main PK parameters of the absorption rate constant (K_α ), the absorption half-life (t_{1/2 Kα} ), the elimination rate constant (K_e ), the elimination half-life (t_1/2Ke ), and the area under concentration-time profile (AUC_0-∞ ) were 0.3 1/h, 2.29 hr, 0.039 1/h, 17.64 hr, and 855.78 mg.h/L, respectively. Following intravenous administration, the concentration-time curve fitted to a two-compartmental open model without absorption. The primary PK parameters of the distribution rate constant (α), the elimination rate constant (β), the distribution half-life (t_1/2α ), the elimination half-life (t_1/2β ), the apparent distribution volume (V_SS ), the total clearance (CL), and AUC_0-∞ were 9.62 1/hr, 0.039 1/hr, 0.072 hr, 17.71 hr, 0.33 L/kg, 0.013 L h^-1  kg^-1 , and 386.23 mg.h/L, respectively. Finally, the BA was calculated to be 22.16%. Overall, this study will provide some fundamental information on PK properties in the development of a new formulation SDZ in the future and is partially beneficial for the appropriate usage of SDZ in aquaculture.

Pharmacokinetics and ex vivo pharmacodynamics of Minocycline against Salmonella abortus equi in donkey plasma and tissue cage fluid

Tissue Cage (TC) model was used to evaluate the pharmacokinetics and ex vivo pharmacodynamics of Minocycline (MINO) after intramuscular (IM) administration to donkeys at 4 mg/kg body-weight. The C_max of MINO with 1.79 and 2.63 μg mL^-1 was obtained at 2.96 and 1.41 h in TCF (tissue cage fluid) and plasma respectively. The absorption half-lives (t_1/2ka) of MINO were calculated to be 0.71 h in TCF and 0.32 h in plasma, whereas the elimination half-lives (t_1/2ke) were 10.46 h in TCF and 5.95 h in plasma. The distribution volume (V_d/F) of MINO was estimated to be 1.84 L kg^-1 in TCF and 1.28 L kg^-1 in plasma. The total clearance (CL_b/F) of MINO was computed as 0.12 and 0.15 L/ (h·kg) in TCF and plasma respectively. The area under the concentration-time curve (AUC) of MINO was 32.77 μg mL^-1h in TCF and 25.27 μg mL^-1h in plasma, respectively.The ex vivo time-kill curves were established for plasma and TCF samples using Salmonella abortus equi. The MIC and MBC of MINO against salmonella were 0.08 and 0.16 μg mL^-1 for plasma, 0.04 and 0.08 μg mL^-1 for TCF. The plasma C_max/MIC and AUC/MIC values after IM administration were 32.88 ± 9.87 and 315.88 ± 42.65 h, respectively. The TCF C_max/MIC and AUC/MIC values after IM administration were 44.75 ± 9.32 and 819.25 ± 65.23 h, respectively. The values of T > MIC were approximately >36 h in plasma and > 65 h in TCF. These findings from this study suggest that MINO may be therapeutically effective in diseases of donkeys caused by salmonella when used at a dose of 4 mg/kg IM administration.