Pharmacokinetics of a new ivermectin/praziquantel oil suspension after intramuscular administration in pigs

A new oil suspension containing 0.15% ivermectin and 15% praziquantel for intramuscular injection was developed, and corresponding pharmacokinetics studies were conducted in swine. The combination product is a white- to cream-colored oil suspension and its physical properties such as settling volume ratio, redispersibility, syringeability and flowability are well consistent with the Technical Standards by the Ministry of Agriculture of the People's Republic of China. The pharmacokinetic study consists of two parts. First, the experiments were carried out to compare the pharmacokinetic parameters of the combination product and those same products with praziquantel or ivermectin removed merely. The results showed that no significant change in the major pharmacokinetic parameters (t(1/2z), T-max, C-max, AUC(INF), TimeDur) was observed when either of the component was removed from the combination product, indicating that ivermectin and praziquantel do not interfere with each other when being used together. Second, the pharmacokinetics of the combination product were compared with those of their respective single product. The results showed that the C-max (15.94 ng/mL) of ivermectin in combination product was 9.01 times higher than the single product, while the AUC(INF) (1925.61 ng h/mL) was 6.02 times higher. meanwhile, the C-max (1.48 mu g/mL), AUC(INF) (17.08 mu g h/mL), t(1/2z) (20.25 h), TimeDur3 (42.01 h) and TimeDur4 (16.60 h) of praziquantel in combination product were improved with a factor of 5.48, 13.66, 8.58, 10.10 and 7.31 times when compared with the single product, respectively. Therefore, the efficacy of the combination product was significantly prolonged, especially for praziquantel, so that comprehensive efficacy of controlling parasites sensitive to ivermectin and praziquantel can be achieved with one-single use of it. (C) 2011 Elsevier B.V. All rights reserved.