NPH Insulins, or "Neutral Protamine Hagedorn", now describes the set of insulins using Isophane / Protamine as their suspension. In North America, Humulin N and Novolin N are the most common brands of NPH insulin. Another term for this type of insulin is Isophane; it's commonly used to describe this insulin type outside of North America.
NPH was first launched in 1946 in Denmark by Novo Nordisk as the first longer-lasting neutral pH insulin for human use. "Hagedorn", was the chief scientist who invented it.
The difference between NPH/isophane insulin and PZI insulin is the amount of protamine in the suspension. PZI has more of it and this is what makes it a slow-acting insulin, in contrast to NPH/isophane being an intermediate-acting (or in some cats, short-acting) one, as the additional protamine extends the duration.
Specifications of NPH/isophane insulin[edit | edit source]
British National Formularydefines this type as: A sterile suspension bovine or porcine or of human insulin in the form of a complex obtained by the addition of protamine sulphate or another suitable protamine.
British Pharmacoepia and United States Pharmacopia definitions:
Sterile buffered suspension of insulin in the form of a complex obtained by addition of suitable protamine. Prepared from crystalline insulin. pH 6.9 - 7.5 iso-osmotic with blood. Contains for each 100 units of insulin, 300 - 600 g protamine sulphate and not more than 40 g zinc, a suitable bactericide and sodium phosphate as buffering agent.
USP specification: Sterile suspension of zinc insulin crystalline and protamine sulphate in buffered water for injection. Solid phase contain crystals of insulin
protamine and zinc; 40, 80, 100 units/ml. Contains glycerol, metacresol, phenol sodium phosphate and zinc.
Additional details[edit | edit source]
NPH is the most widely used type of insulin for treatment of diabetic dogs, but is shorter-acting and less predictable in cats. With a peak of 1.5-6 hours and duration of 4-10 hours, if it is successfully used, twice-daily dosing is a must. See also Humulin N 101 for Cats at link below.
This 1987 study of direct comparisons between R and NPH insulins in dogs, found R insulin to be absorbed better than NPH and suggests that NPH insulin may have an earlier peak and shorter duration than previously thought.
NPH/isophane insulins[edit | edit source]
The following commercial insulins are all generically NPH insulins:
|Hypurin Bovine Isophane|
|Iletin I NPH|
(No longer produced.)
|Hypurin Porcine Isophane|
Hypurin Pork NPH
|Iletin II NPH|
(No longer produced.)
|Humulin N, Humulin I|
|Novolin N, Insulatard|
ReliOn/Novolin NPH, Protaphane
Other commonly used names are:
- NPH insulin, NPH
- isophane insulin
Further Reading[edit | edit source]
- Wiki cases--Feline NPH-isophane users
- Absorption Kinetics of Regular (Neutral), Isophane (NPH), and Protamine Zinc Insulin (PZI) in Normal Cats-Domestic Animal Endocrinology-1990
- Insulin Therapy in Cats With Diabetes Mellitus--JAVMA-1983
Contains peak, onset & duration information for NPH/isophane & PZI insulins in cats.
- Insulin Therapy in Cats with Diabetes Mellitus-JAVMA-1983
Some feline Time Activity information re: NPH/isophane & PZI insulins.
- Wiki cases--Canine NPH-isophane users
- Absorption Kinetics of Regular (Neutral) & Isophane (NPH)Insulin in the Normal Dog-Domestic Animal Endocrinology-1987
- The Use of Isophane (NPH) Insulin for the Control of Diabetes Mellitus in Dogs-Acta Vetinaria Scandinavia--1992
- InChem--with information on NPH/isophane insulins.
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References[edit | edit source]
- Selecting an Insulin for Treatment of Diabetes Mellitus in Dogs 7 Cats-Nelson-Page 41
- British National Formulary-Isophane/NPH Insulin Definition
- British Pharmacoepia (BP) & United States Pharmacoepia (USP)-Isophane/NPH Insulin Defined
- BD Diabetes-Insulin Choices for Cats
- BD Diabetes-Insulin Choice for Dogs
- Ask the D Team-2002- Some People Find it Inconsistent Also
- International Journal of Pharmaceutical Compounding-Page 3
- Humulin N 101 For Cats-Gorbzilla.com
- Absorption Kinetics of Regular (R)/(Neutral) & Isophane (NPH) Insulin in the Normal Dog-Domestic Animal Endocrinology-1987