Ivermectin is a new, broad-spectrum, highly effective, and low-toxicity antiparasitic antibiotic. It is particularly effective in eliminating both internal and external parasites, especially nematodes and arthropods. However, it is ineffective against tapeworms, flukes, and protozoa.
Internal parasite species that can be treated with ivermectin include gastrointestinal worms (primarily roundworms) in horses, cattle, pigs, sheep, and goats as well as lungworms in cattle and pigs. External parasites that can be treated with ivermectin in large animals include lice, mites, and grubs.
As a macrocyclic lactone antiparasitic drug, ivermectin's mechanism of action against nematodes and arthropods involves increasing the release of the inhibitory neurotransmitter γ-aminobutyric acid (GABA) and opening glutamate-gated chloride ion channels. This enhances the permeability of the neural membranes to chloride ions, thereby disrupting the transmission of neural signals. Ultimately, this leads to paralysis of the parasites' nervous system, causing their muscle cells to lose the ability to contract, which results in the death of the parasites.