The distribution and some pharmacokinetic parameters of ivermectin in pigs

Abstract

Ivermectin was injected subcutaneously into five pigs at the usual dose rate of 300 micrograms/kg and found to distribute well to all tissues and body fluids which were sampled 24 h post-injection. Ivermectin was detected in the contents and mucus at all levels of the gastrointestinal tract. The drug was excreted in bile, with high concentrations of the drug in the intestines and faeces. High concentrations of ivermectin were measured in skin, ears and ear wax, suggesting that the drug should be effective in the treatment of ectoparasitic infestations, particularly ear mites. The high lipid solubility of the drug may explain the high concentrations found in ear wax and skin. Ivermectin was also detected in the body fluids and tissues of an untreated pig penned with the treated animals. Direct contact appeared to be necessary for transfer of ivermectin from the treated to the untreated pig but coprophagia or urine drinking is a possible explanation. The pharmacokinetics of ivermectin administered subcutaneously at a dose rate of 300 micrograms/kg to six pigs were studied. There was marked individual variation in the pharmacokinetics of ivermectin. In one pig the area under the plasma concentration-time curve was particularly high. This may reflect individual variation in uptake and excretion of the drug. The mean elimination half-life of the drug was 35.2 h, suggesting that the drug is cleared slowly from pigs with drug detectable in plasma for 6-10 days. This persistence should allow a short period of protection before re-infection with parasites.

Bioavailability of a commercial formulation of ivermectin after subcutaneous administration to sheep

“…This fact has been reported in cows, 21,27 sheep, 9,11,16 goats, 28 pigs, 29 and deer. This fact has been reported in cows, 21,27 sheep, 9,11,16 goats, 28 pigs, 29 and deer.…”

The effects of body composition on the pharmacokinetics of subcutaneously injected ivermectin and moxidectin in pigs

“…The disposition of IVM in plasma following s.c. administration to the fat pigs in this study is very similar to that observed by Friis and Bjørn (1995). Scott and McKellar (1992), however, reported an earlier, higher C max and a lower AUC , but these results were collected using pigs weighing 18–26 kg at treatment. The AUC collected by Scott and McKellar (1992) in these small pigs is similar to the AUC in the thin pigs of this study.…”

Ivermectin in Senegalese Peulh Sheep: Influence of Sex on Plasma Disposition

“…It has been suggested that the high lipid solubility of the endectocide agents may facilitate their storage in the adipose tissue, which may then act as a drug reservoir that contributes to the persistence of these compounds in the body (Lanusse and Prichard, 1993;Lifschitz et al, 1999;Hennessy and Alvinerie, 2002). Subcutaneous injection distributes a much greater proportion of the ivermectin into lipid reservoirs, which increases the residence time almost threefold in cattle (Toutain et al, 1988;Lanusse et al, 1997), sheep (Marriner et al, 1987), pigs (Scott and McKellar, 1992), horses (Marriner et al, 1987;Perez et al, 1999) and goats (Alvinerie et al, 1993). Furthermore, metabolism of drugs may differ in females owing to hormonal influences on physiological functions.…”