Diabetes in Pets
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Close-up of Iletin vial-1923. The insulin was all beef, came in varying strengths and was not highly purified.

Regular, neutral, Toronto or Toronto insulin. A term used most often in Canada, Toronto simply another name for R or neutral insulin, no matter who makes it or its origin. Toronto was where Frederick Banting and Charles Best did their work discovering insulin, and terming such insulin Toronto insulin honors their work there.

Human activity profile for r-DNA/GE/GM R (Regular)/Neutral insulin. See links for cat & dog activity.

A short-acting, soluble, non-suspended insulin produced from r-DNA/GE/GM, bovine, or porcine sources. R or neutral insulin is basically zinc insulin crystals dissolved in clear fluid with nothing added to alter its action or speed[1]. 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[2] in R/neutral; it's totally dissolved and soluble, meaning it can safely be used intravenously.

The very small insulin particles in semilente insulin are suspended by zinc[3]. Semilente is cloudy, has an acetate buffer and cannot be used intravenously.

R/Neutral insulin cannot be reliably mixed with Lente or Ultralente insulins[4][5]. Semilente can; the ratio of 3 parts semilente insulin to 7 parts ultralente insulin produces Lente insulin[6].


R/Neutral Insulins

R/Neutral Insulins

All Short acting
All soluble

Bovine/Beef

Hypurin Bovine Neutral

Bovine/Beef

Hypurin Vet Neutral

Bovine/Beef

Insuvet Neutral

Bovine/Beef

Iletin I R
(No longer produced.)

Porcine/Pork

Hypurin Porcine Neutral
Hypurin Pork Regular

Porcine/Pork

Pork Actrapid

Porcine/Pork

Iletin II R
(No longer produced.)

R-DNA

Humulin R, Humulin S

R-DNA

Insuman Rapid

R-DNA

Actrapid, Novolin R
ReliOn/Novolin R

Further Reading

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References

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