A comparative kinetic study of doramectin and moxidectin in zebu Gobra cattle (Bos indicus).

The plasma kinetics of doramectin and moxidectin were evaluated in zebu Gobra under field conditions after subcutaneous administration of 0.2 mg kg(-1) of commercially available formulations for cattle. The results indicate that the absorption of moxidectin from the site of injection was significantly faster (absorption half-life [t1/2ab] = 0.7 day) than that of doramectin (t1/2ab = 3.1 days). Moxidectin peak plasma concentration (Cmax) was reached significantly earlier (tmax = 0.4 day) compared with that of doramectin (tmax = 5.3 days). No differences in Cmax values were observed; the area under the concentration-time curve was higher for doramectin (475 ng day ml(-1)) compared with moxidectin (198 ng day ml(-1)), while the mean residence time was longer for moxidectin (13.4 days) compared with doramectin (9.4 days). These results obtained give interesting information on doramectin and moxidectin pharmacokinetics in zebu Gobra, which show a similar pharmacokinetic profile as in other cattle.

Eprinomectin in dairy zebu Gobra cattle (Bos indicus): plasma kinetics and excretion in milk.

The pharmacokinetics and mammary excretion of eprinomectin were determined in zebu Gobra following topical administration of 0.5 mg kg(-1). The kinetics of plasma and milk was analysed using a one-compartment model. The maximum plasma concentration of 8.83+/-2.15 ng ml(-1) occurred 1.30 days post-administration. The area under the plasma concentration-time curve was 30.63+/-5.56 ng day(-1) ml(-1) and the mean residence time was 3.38+/-0.60 days. Eprinomectin was detected in milk at the first sampling time and thereafter for at least 8 days. The systemic availability of eprinomectin was significantly lower than that for other breeds of cattle. Comparison of the milk and plasma data demonstrated the parallel disposition of the drug in the milk and plasma with a milk/plasma ratio of 0.094. The very low extent of mammary excretion supports the permitted use of eprinomectin in lactating zebu Gobra.