Effect of multidrug resistance modulators on the activity of ivermectin and moxidectin against selected strains of Haemonchus contortus infective larvae

Abstract

Effect of multidrug resistance modulators on the activity of ivermectin and mo Effect of multidrug resistance modulators on the activity of ivermectin and mo Effect of multidrug resistance modulators on the activity of ivermectin and mo Effect of multidrug resistance modulators on the activity of ivermectin and mo Effect of multidrug resistance modulators on the activity of ivermectin and moxidectin of xidectin of xidectin of xidectin of xidectin of

In vitro evaluation of ivermectin, moxidectin, albendazole and pyrantel against cyathostomins of horses

“…The in vitro egg hatch test (EHT), larval development test (LDT) and the larval migration test (LMT) are tools that can also aid the diagnosis of resistance, and to screen for alternative medicines (KOTZE et al, 2006;PEACHEY et al, 2016;LÉGARÉ & OUELLETTE, 2017). Although the tests have some particularities, they have been largely used in ruminant nematodes, particularly sheep (GILL et al, 1995;VÁRADY & CORBA, 1999;MOLENTO & PRICHARD, 2001) and cattle (DEMELER et al, 2010). A few studies have used these in vitro methods for horses (CRAVEN et al, 1999;KÖNIGOVÁ et al, 2003;LIND et al, 2005;PEACHEY et al, 2016).…”

“…Resistance to BZD was demonstrated in 33 out of 42 farms (79%), when using FECRT, and in 32 out of 52 farms (62%), when using the EHT. The larval migration on agar test (LMAT) is a variation of the LMT, and allows the observation of ruminant nematode larvae that pass through a mesh and an agar gel layer, which serve as a barrier (MOLENTO & PRICHARD, 2001). Thus, with the advancement of cyathostomin multidrug resistance, the standardization of another in vitro test may become an important aid to drug monitoring.…”

“…The concentrations (in triplicates) were prepared by dissolving each drug concentrations in distilled water and DMSO (3%). Fresh larvae (30 days old) were exsheathed with 0.3% sodium hypochlorite for 30 min before the test (MOLENTO & PRICHARD, 2001). A total of 400 larvae were placed in the compound solution in 24-well plates at a volume of 1 ml/well.…”

“…For the first incubation period, the plates were incubated at 28°C for 6 h. The second incubation began with the addition of 1 ml of 1.4% agar into the solution. This 2-ml solution was then transferred into a previously prepared individual apparatus (MOLENTO & PRICHARD, 2001) at 28 °C for 18h. During this period, the larvae were exposed to a 150 W light bulb to stimulate L3 migration.…”

Evaluation of resistance in a selected field strain of Haemonchus contortus to ivermectin and moxidectin using the Larval Migration on Agar Test

“…Various in vitro methods have been developed in the last 30 years (Gill et al 1995, d' Assonville et al 1996, Molento & Prichard 2001, Taylor et al 2002, Coles et al 2006, Demeler et al 2010, having the main characteristic of avoiding the "animal -in vivo" effect (i.e. breed, age, body fat/score), which can significantly alter the drug pharmacokinetics, as a consequence of different rates of absorption, metabolism and the time to reach the target tissues.…”