Comparison of the anthelmintic efficacy of oxfendazole or ivermectin administered orally and ivermectin administered subcutaneously to sheep during the periparturient period

Abstract

The suppression of nematode egg output in faeces was measured in ewes treated just before lambing with either oxfendazole or ivermectin by oral drench or with ivermectin by subcutaneous injection. Ivermectin and oxfendazole given orally were similarly effective, whereas ivermectin given by subcutaneous injection extended the period of suppressed egg output by about one week. The more persistent anthelmintic effect of ivermectin given subcutaneously was probably due to its extended half-life in the plasma of treated sheep. Plasma pepsinogen activity was less in the sheep given anthelmintic than in the untreated controls. Ivermectin caused a significantly greater reduction in pepsinogen activity than oxfendazole and was more effective when given subcutaneously than when given orally.

Factors affecting the efficacy of ivermectin against Heligmosomoides polygyrus (Nematospiroides dubius) in mice

“…At 20 mg kg-1 ivermectin was totally effective in killing all arrested worms, whereas pyrantel failed to affect such larvae. This result is consistent with studies on arrested trichostrongyles in sheep (McKellar and Marriner, 1987), pigs (Murrell, 1981) and cattle (Barth and Preston, 1987).…”

“…Furthermore, we demonstrated that the anthelmintic effect of ivermectin was more persistent in CFLP than in NIH mice, especially when administered subcutaneously. This is consistent with observations made by McKellar and Marriner (1987) on trichostrongyle infections in sheep and by Barth (1983) in cattle. The explanation for the persistence of ivermectin after subcutaneous administration may be slow drug release from the site of injection (Lo et al, 1985 ) leading eventually to higher and long-lasting plasma levels (Campbell, 1985;McKellar and Marriner, 1987).…”

Duration of Anthelmintic Effect of Three Formulations of Ivermectin (Oral, Injectable and Pour-on) Against Multiple Anthelmintic-Resistant Haemonchus contortus in Sheep

“…This may be due to the fact that, following oral administration, the drug binds with organic matter in the rumen of sheep (Hennessy et al, 2000), leading to low bioavailability. Also, the more persistent anthelmintic effect of ivermectin given subcutaneously might be due to the extended half-life of the drug in plasma of treated sheep (McKellar and Marriner, 1987).…”

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

“…[6][7][8][9][10][11][12][13][14][15][16][17][18][19] However, most of those investigations were not a complete study with regard to compartmental and noncompartmental analysis. [6][7][8][9][10][11][12][13][14][15][16][17][18][19] However, most of those investigations were not a complete study with regard to compartmental and noncompartmental analysis.…”

“…Total body clearance Vd ss Volume of distribution at steady state Vd a Apparent volume of distribution C max Maximum plasma ivermectin concentration t max Time to reach C max t 1/2α Half-life associated with the α phase t 1/2β Half-life associated with the β phase Vd c Apparent volume of distribution for the central compartment t 1/2k10 Half-life for elimination from the central compartment Although the pharmacokinetic behavior of ivermectin has been widely studied in sheep, [6][7][8][9][10][11][12][13][14][15][16][17][18][19] reports on the pharmacokinetic variables are scarce. On the other hand, it has been reported 20 that the pharmacokinetic variables of ivermectin differ on the basis of the formulation used, route of administration, and animal species.…”