In Vitro Study of Benzimidazole Derivatives, Tetrahydropyrimidines and Macrocyclic Lactones Therapeutic Efficacy in Dog Hookworms

Abstract

The study was conducted using faecal samples from 62 dogs. We tested the ovicidal and larvicidal effects of albendazole (ABZ), mebendazole (MBZ), fenbendazole (FBZ) and flubendazole (FLU) by Egg hatch assay (EHA) and larval development assay (LDA). For pyrantel (PYR) and selamectin (SEL) we tested the larvicidal effects by LDA. In all in vitro tests, benzimidazoles efficacy was low, with a high risk of inducing resistance phenomena. In EHA more than 50% of the hookworm eggs hatched, revealing a low efficacy of all tested benzimidazoles. The regression line was positive for all benzimidazoles, FBZ having the smallest value of the Y parameter (62.62), and lower risk of resistance. When testing the larvicidal effects, a superior efficacy of benzimidazoles was observed. The lowest MIC was for MBZ (0.8672μg/ml). ABZ had a very poor effect (8.46750 μg/ml). The Y parameter showed a lower risk of inducing resistance for MBZ (Y= -64.14) and FBZ (Y= -27.89). Pyrantel and Selamectin were very effective, presenting also a very low risk of inducing resistance phenomena. For PYR and SEL, MIC was 0.2131 μg/ml and 2.7921 μg/ml, respectively. The Y parameter was -448.37 for PYR and -62.74 for SEL, with minimal risk of inducing the adaptive phenomena.