There are different ivomec products, some more effective as wormers than others. Both are made by the same company. The main difference is that there is no egg withdrawal with eprinex when worming. All other ivomec products normally have a 14 day withdrawal. All ivomec products including eprinex are effective against mites, but not lice. Ivermectin pour on and eprinex arnt very effective against cecal worms. Large roundworms are showing some signs of resistance with ivermectin pour on and eprinex. Ivermectin injectable is useless against worms in chickens.