Canine Diabetes Wiki
Iletin I R
R, Neutral by Eli Lilly
Bovine 85% Porcine 15%
U100 none
Action in dogs:
  • onset 10-30 minutes,
  • peak 1-5h,
  • duration 4-10h
Line: Iletin
Also known as:
Similar to:
Use and Handling:
Shelf Life: 24 months Type: soluble, clear
When Opened: 28 days room temp.
In Pen: N/A
Notes: Protect from light and heat
Do Not Freeze,
May be used intravenously
See Hypurin Bovine Neutral, Insuvet Neutral, or Betasint Bovine Corriente for current handling notes for bovine R-neutral insulin.
Iletin I R

Iletin I Regular/Neutral/Normal beef/pork insulin. The insulin was discontinued by Lilly in 1998.

Lilly human insulins1992charts

Lilly insulin products-1992. This insulin is shown as Iletin I Lente.

Note that some countries have the brand name in U40 strength.

North American brand name for Eli Lilly's 100% bovine AND bovine/porcine mix insulins. [1][2] 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. [3] There are no beef/pork mixed R/neutral insulins on the market today--they are all either pure pork or pure beef.

The closest current equivalents are Hypurin Bovine Neutral [4][5] and Betasint Bovine Corriente by Beta Laboratorios.[6]

A short-acting, soluble, non-suspended insulin produced from r-DNA/GE/GM, bovine, or porcine sources. From 1921 to the 1930's when PZI was developed, R was the only kind of insulin available.

While both R/neutral and semilente insulins are considered fast-acting, they differ in a few ways. As above, there's no suspension or buffer [7] in R/neutral; it's totally dissolved and soluble, meaning it can safely be used intravenously. [8]

The very small insulin particles in semilente insulin are suspended by zinc. [7] Semilente is cloudy, has an acetate buffer and cannot be used intravenously.

R/Neutral insulin cannot be reliably mixed with Lente or Ultralente insulins. [9][10] Semilente can; the ratio of 3 parts semilente insulin to 7 parts ultralente insulin produces Lente insulin. [7]

R/Neutral Insulins[]


  1. Discontinuation of Lilly Iletin I line of beef/pork insulins. Iletin I R is at left.. Eli Lilly.
  2. Insulin Update-Discontinuation of Iletin Beef/Pork insulins. Nora Apothecary.
  3. Humulin R patient leaflet. Eli Lilly.
  4. Patient Information-Hypurin Bovine Neutral. Net Doctor uk.
  5. Hypurin Bovine Neutral. Wockhardt UK.
  6. Prescribing Bovine Insulin.
  7. 7.0 7.1 7.2 DeRuiter, Jack. Insulin Preparations-Regular Insulin. Auburn University. Cite error: Invalid <ref> tag; name "Auburn" defined multiple times with different content Cite error: Invalid <ref> tag; name "Auburn" defined multiple times with different content
  8. Maddison, Jill E.,Page, Stephen W.,Church, David B. (2008). Small Animal Clinical Pharmacology. Saunders Ltd..
  9. Deckert, T. (1980). Intermediate-Acting Insulin Preparations: NPH (Isophane) & Lente. Diabetes Care.
    Note--in 1980, there were no r-DNA/GE/GM insulins
  10. Resource Guide. American Diabetes Association (2005).

More information[]