Comparative pharmacokinetics of some injectable preparations containing ivermectin in dogs.

Little is known about the kinetics of ivermectin formulations following subcutaneous administration in dogs. The vehicle components used in production may change the pharmacokinetics of the drug. The present study was aimed at the comparison of the pharmacokinetics of seven injectable ivermectin formulation of different brand names (A-G). The animals were allocated to seven groups, each comprising seven dogs. The dogs were administered ivermectin at a dose of 200 microg/kg bw by subcutaneous route and blood samples were collected from all groups up to 288h post-injection. Plasma ivermectin analyses were performed using a HPLC with a fluorescence detector. Compared to Group 1(A), it was determined that statistically significant differences existed in Groups 2(B), 3(C), 4(D), 5(E), and 7(G) for C(max) values; and in Groups 3(C), 4(D), 6(F), 7(G) for AUC(0-->288) and AUC(0-->infinity) values. These values were highest in Group 1(A) and lowest in Group 7(F). The results obtained in the present study demonstrated that, in cases which require subacute administration, optimal exposure is achieved with the preparation A. However, it must be noted that this evaluation was based on pharmacokinetic parameters and not antiparasitic efficacy.