Efficacy of oral, injectable and pour-on formulations of moxidectin against gastrointestinal nematodes in cattle in New Zealand

Anthelmintic resistance in gastrointestinal nematodes of dairy cattle in the Macalister Irrigation District of Victoria

“…Many pour‐on products also have the advantage of no milk withholding period over equivalent injectable formulations. However, the bioavailability of pour‐on preparations is generally lower than after subcutaneous injection or oral administration and there can be large variation between animals in pharmacokinetics and efficacy as a result of oral absorption through licking . In some circumstances, this may increase selection pressure for anthelmintic resistance because of the potential for under‐dosing of a proportion of the treated animals …”

The pharmacokinetics of moxidectin following intravenous and topical administration to swine

“…In this study, plasma MXD concentrations associated with almost all time points were above 0.5 ng/ml; hence, we expect that MXD will be effective against some species of parasite with this dose regimen. However, when comparing the efficacy of MXD by different routes of administration, that is, i.v., oral, s.c., and pour‐on, in cattle, it was found that when administered to cattle by s.c. at 0.2 mg/kg, the plasma concentration file of MXD was considerably higher than after pour‐on, but interestingly, both of them exposed the similar efficacy which remains unexplained by the result (Leathwick & Miller, ). Besides, the plasma concentration of MXD followed by oral was lower than that followed by s.c., but the efficacy against C. oncophora was higher than the s.c. route (Leathwick & Miller, ).…”

“…However, when comparing the efficacy of MXD by different routes of administration, that is, i.v., oral, s.c., and pour‐on, in cattle, it was found that when administered to cattle by s.c. at 0.2 mg/kg, the plasma concentration file of MXD was considerably higher than after pour‐on, but interestingly, both of them exposed the similar efficacy which remains unexplained by the result (Leathwick & Miller, ). Besides, the plasma concentration of MXD followed by oral was lower than that followed by s.c., but the efficacy against C. oncophora was higher than the s.c. route (Leathwick & Miller, ). These data might attribute to the ruminal and abomasal content of ruminants which conserve and bound to drugs in the digesta (Lifschitz et al., ).…”

“…To make better use of the antiparasitic effect of MXD, it is imperative to characterize the plasma disposition kinetics of the drug. The pharmacokinetics of MXD have been widely reported in many species such as rabbits which were given MXD topically at a dose of 1 mg/kg BW (Pan et al., ), goats which were given subcutaneously (s.c.) and orally at 0.2 mg/kg BW (Escudero et al., ), sheep which were given s.c. at 0.2 mg/kg BW (Perez, Nunez, Palma, Riquelme, & Arboix, ), and cattle which were given orally, s.c., and topically at 0.2, 0.2, and 0.5 mg/kg BW, respectively (Leathwick & Miller, ). In pigs with different body fat content, the plasma kinetic profile of MXD was studied, and results showed that comparing to fat pigs, lean pigs had more rapid distribution and elimination rate than fat pigs when MXD was administered intravenously (i.v.…”

“…The AUC value of pour‐on in this study was 1776.24 ± 659.52 ng hr ml −1 . In cattle, when MXD was administered s.c. (0.2 mg/kg BW), orally (0.2 mg/kg BW), and topically (0.5 mg/kg BW), the AUCs were 105.64, 20.88, and 9.14 ng hr ml −1 , respectively (Leathwick & Miller, ). The AUCs of MXD at 0.2 mg/kg after s.c. administration to nonpregnant and pregnant sheep were 109.8 ± 37.3 ng hr ml −1 and 143.6 ± 24.7 ng hr ml −1 , respectively (Perez et al., ).…”