Pharmacokinetics of florfenicol and its metabolite florfenicol amine in the plasma, urine, and feces of fattening male donkeys following single oral administration

Abstract

Florfenicol (FF) is a commonly used antibacterial agent in animals. We investigated the pharmacokinetics of FF and its metabolite florfenicol amine (FFA) in donkeys. Donkeys were administered FF (30 mg/kg bodyweight, p.o.). Pharmacokinetic parameters were calculated using a non-compartmental model. The FF (FFA) pharmacokinetics parameters were characterized by along elimination half-life (t_{1/2 kz}) of 5.92 h (15.95 h), plasma peak concentration (C_max) of 0.13 μg/mL (0.08 μg/mL), and the time taken to reach C_max (T_max) of 0.68 h (0.72 h). The area under plasma concentration-time curve and mean residence time of FF (FFA) in plasma were 1.31 μg·mL^-1·h (0.47 μg·mL^-1·h) and 10.37 h (18.40 h), respectively. The t_{1/2 kz} of FF and FFA in urine was 21.93 and 40.26 h, and the maximum excretion rate was 10.56 and 4.03 μg/h reached at 25.60 and 32.20 h, respectively. The respective values in feces were 0.02 and 0.01 μg·h^-1 reached at 33.40 h. The amount of FF and FFA recovered in feces was 0.52 and 0.22 μg, respectively. In conclusion, FF (FFA) is rapidly absorbed and slowly eliminated after a single oral administration to donkeys. Compared to FF, FFA was more slowly eliminated. FF (FFA) is mostly excreted through urine.

Keywords: antibiotic; donkey; florfenicol; florfenicol amine; pharmacokinetics; urinary excretion.

Figure 1

Plasma concentration of florfenicol (FF, O) and florfenicol amine (FFA, Δ) in five donkeys after a single oral dose of 30 mg/kg bodyweight.

Figure 2

Semilogarithmic plot of florfenicol (FF, O) and florfenicol amine (FFA, Δ) urinary concentration vs. time following a single oral dose at 30 mg/kg bodyweight in donkeys.

Figure 3

Semilogarithmic plot of florfenicol (FF, O) and florfenicol amine (FFA, Δ) fecal concentration vs. time after a single oral dose of 30 mg/kg bodyweight in donkeys.