Ivermectin in senegalese peulh sheep: influence of sex on plasma disposition.

The plasma disposition kinetics of ivermectin following a single subcutaneous administration of 0.2 mg/kg was investigated in male and female Senegalese Peulh sheep. Ten clinically healthy animals (5 males and 5 females) weighing 38-45 kg were used in this trial. Blood samples were collected by jugular puncture at different times between 0.5 h and 30 days post treatment. After plasma extraction and derivatization, samples were analysed by HPLC with fluorescence detection. Computerized kinetic analysis was carried out and mean parameters were statistically compared with the Mann-Whitney U-test. The area under the concentration-time curve (AUC) was significantly higher (p < 0.0027) in females than in males. Although the differences in maximum concentration (C (max)), mean residence time (MRT) and half-life of elimination (t (1/2el)) between males and females did not achieve statistical significance, values tended to be higher in females. Sex differences may be parallel with the level of storage in fat. Further investigations are required to improve the use of ivermectin in Senegalese sheep and findings may be used to predict optimal anthelmintic strategies for management of African species depending on the parasites present in a production system.

Pharmacokinetics of ivermectin in zebu Gobra (Bos indicus).

Plasma disposition kinetics of ivermectin was evaluated in a West African cattle breed. Five clinically healthy zebu Gobra cattle (Bos indicus) weighing 220-270 kg were treated (0.2 mg kg-1) with a commercially available ivermectin formulation for cattle. Blood samples were collected by jugular puncture at different times between 0.5 h and 40 days post-treatment. After plasma extraction and derivatization, samples were analysed by HPLC with fluorescence detection. Ivermectin was detected in plasma between 30 min and 20 days post-treatment. The observed peak plasma concentration (Cmax) was 46.3+/-13.8 ng ml-1 and the time to reach Cmax (t(max)) was 0.9+/-0.2 day. The values for the absorption half-life (t1/2ab) and the elimination half-life (t1/2el) were 0.3+/-0.2 and 2.8+/-0.7 days, respectively. The calculated area under the concentration-time curve (AUC) was 185.2+/-12.1 ng day ml-1 and the mean residence time (MRT) was 4.2+/-1.3 days. The availability of ivermectin is low in zebu Gobra in comparison to other breeds cattle but equivalent to that reported in the yak and is likely to be due to physiological characteristics of this breed.