Abstract: The antiparasitic activity of ivermectin depends 011 the presence of an active drug concentration at the site of parasites location for an adapted length of time. lvermectin interactions with another concurrently administered drug can occur. Concomitant administration of sorne drugs can increase the bioavailability of simultaneously administered ivermectin. This can, in sorne cases, become a useful pharmacological strategy to improve its antiparasitic efficacy and to delay the development of resistance in livestock or, in other cases, lead to adverse drug reactions and toxicities. On the other hand, other interactions can result in lower levels of this drug, determining that moderate resistant residual populations of the parasites may persist to contarninate pastures. The characterisation of ivermectin interac tions can be used to predict and optimisc the valúe of the parasiticide effects. This article reviews the pharmacological interactions of ivermectin in several domestic animal species.
