Serum kinetics of diminazene aceturate following intramuscular (IM) administration of diminazene aceturate alone at 3.5 mg/kg and its combination with oxytetracycline at 20 mg/kg were evaluated in 6 healthy male Sahel goats to ascertain the effect of oxytetracycline on serum concentration and pharmacokinetic parameters of diminazene aceturate. Two groups (A and B) of three goats each were used, and oxytetracycline was administered 30 minutes prior to diminazene aceturate administration. Blood samples were collected at various intervals (0.17 h – 72 h) post-drug administration, and diminazene serum concentrations were measured using the method of Klatt and Hadju. Kinetic determinants were calculated employing a two-compartment open model. Mean serum concentrations of diminazene aceturate of 2.43 ± 0.95 µg/ml and 1.73 ± 0.44 µg/ml at 0.17 h were measured in groups A and B, respectively. These serum concentrations were found to increase until a peak concentration of 6.91 ± 0.59 µg/ml and 7.55 ± 1.20 µg/ml were reached at 2.0 h in groups A and B, respectively. The peak concentrations subsequently decreased at 72 h post diminazene aceturate administration with serum concentrations of 0.00 ± 0.00 and 0.32 ± 0.28 µg/ml in groups A and B, respectively. Pharmacokinetics parameters like the volume of distribution (Vd), elimination half-life (T½β), concentration maximum (Cmax), absorption rate constant (α), and area under the curve from 0 to 72 h (AUC0 – 72) were significantly higher in goats treated with diminazene aceturate and oxytetracycline combination while total body clearance (Cl), and elimination rate constant (β), were significantly higher in goats treated with diminazene aceturate alone. The mean residence time (MRT) of diminazene aceturate increased from 19.70 ± 2.53 h in diminazene aceturate treatment to 25.11 ± 1.81 h in diminazene aceturate and oxytetracycline treatment. Oxytetracycline was therefore found to alter the elimination pattern of diminazene aceturate in oxytetracycline pre-treated goats.
Key words: Diminazene aceturate, oxytetracycline, pharmacokinetic parameters, serum kinetics, Sahel goats
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