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Disposition kinetics of ceftriaxone and determination of its therapeutic dose in dogs

Ifeanyi G. Eke
Ukamaka U. Eze
Aruh O. Anaga
Kennedy F. Chah
Boniface M. Anene
Isaac U. Asuzu


Purpose: To evaluate the disposition kinetics of ceftriaxone (CFZ) in dogs with a view to determining its therapeutic dose and dosing frequency.
Methods: Twelve (12) Basenji dogs (n = 4), divided into 3 groups (A, B and C), were used for the study. Ceftriaxone was administered intramuscularly at doses of 12.5, 25, and 50 mg/kg once to groups A, B and C respectively. Plasma CFZ concentration was determined by agar well diffusion assay at 0.25, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, and 24 h post-treatment, and the pharmacokinetic parameters were determined.
Results: Intramuscular injection of CFZ to dogs resulted in rapid absorption, distribution and elimination (p < 0.05). The elimination half-life was short and did not change significantly with increase in dose. Serum concentration of CFZ changed significantly (p < 0.05) with increase in dose of CFZ. The maximum serum concentration (Cmax, 15.00 ± 1.18, 141.37 ± 15.87 and 259 ± 5.21 μg/mL) for groups A, B and C respectively were significantly (p < 0.05) different. The steady state CFZ concentrations; 0.94, 8.81 and 16.19 μg/mL for groups A, B and C, respectively, were significantly (p < 0.05) different. However, there was no significant difference in the time to reach steady state concentrations (Tmax, 00±0.021, 4.00±0.10 and 4.30±0.12 for groups A, B and C respectively). The therapeutic dose of CFZ was therefore determined to be 25 – 50 mg/kg every 4 h.
Conclusion: Ceftriaxone undergoes rapid elimination in dogs with a short elimination half-life, thus making it an inconvenient prescription for out-patients in veterinary clinics.

Keywords: Ceftriaxone, Pharmacokinetic profile, Dogs, Therapeutic dose, Veterinary clinic