Eprinomectin is a semi-synthetic avermectin analogue introduced as a topical endectocide (insecticide, miticide and nematocide) for cattle, including lactating dairy cows. Like all avermectins and milbemycins, eprinomectin acts by binding to parasite glutamate- gated chloride ion channels and disrupts neurotransmission leading to paralysis and death of the parasite, mite or insect.