North American brand name for Eli Lilly's 100% bovine AND bovine/porcine mix insulins. This is the "R"/neutral or soluble type; many more types were also produced. Like all R or neutral insulins, nothing is added (suspensions) to alter the insulin's action or speed. There are no beef/pork mixed R/neutral insulins on the market today--they are all either pure pork or pure beef. The pure beef Iletin I R is equivalent to Hypurin Bovine Neutral, Hypurin Vet Neutral and Insuvet Neutral.