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 name of the laboratory where it was invented. ^[1]

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 one for both dogs and people, ^[2] as the additional protamine extends the duration.

Contents 1 Specifications of NPH/isophane insulin 2 Additional details 3 NPH/isophane insulins 4 References 5 More Information

Specifications of NPH/isophane insulinEdit

British National Formulary ^[3] defines 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: ^[3]

Isophane Insulin

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 detailsEdit

NPH is widely used for treatment of diabetic dogs. ^[4][5] 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. ^[6]

This 1987 study ^[7] 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.

Novo Nordisk's and Lilly's analog insulin mixes NovoLog and Humalog employ protamine/isophane suspension; non-mix Novolog and Humalog do not.

NPH/isophane insulinsEdit

The following commercial insulins are all generically NPH insulins:

NPH/Isophane Insulins
	All Intermediate acting
Bovine/Beef	Betasint Bovine NPH Hypurin Bovine Isophane [8][9][10]
Bovine/Beef	Iletin NPH (No longer produced.)
Bovine/Beef PorcinePork	Iletin I NPH (No longer produced.)
Porcine/Pork	Betasint Porcine NPH Hypurin Porcine Isophane [11][12] Hypurin Pork NPH
Porcine/Pork	Iletin II NPH (No longer produced.) Pork Insulatard [11][13][14] (No longer produced.) Leo Retard (No longer produced.)
R-DNA	Huminsulin Basal, Humulin I Humulin N, Humulin NPH Humulina NPH, Humuline N Humuline NPH, Umuline NPH Humulin ReliOn N
R-DNA	Insuhuman Basal, Insuman Basal Isuhuman Basal, Winthrop Basal
R-DNA	Insulatard, Novolin N Protaphan, Protaphane
R-DNA	ReliOn/Novolin NPH (No longer produced)

Other commonly used names are:

• NPH insulin, NPH
• isophane insulin

ReferencesEdit

More InformationEdit

• Absorption Kinetics of Regular (Neutral) & Isophane (NPH) Insulin in the Normal Dog Goeders LA, Esposito LA, Peterson ME., 1987, Domestic Animal Endocrinology
• The Use of Isophane (NPH) Insulin for the Control of Diabetes Mellitus in Dogs Lorenzen FH., 1992, Acta Vetinaria Scandinavica
• Dosing information on NPH use for dogs Rand, Jacqueline, Fleeman, Linda, University of Queensland
• InChem--with information on NPH/isophane insulins.
• An investigation of the action of Neutral Protamine Hagedorn human insulin in dogs with naturally occurring diabetes mellitus Palm, C. A., et. al, 2009, Journal of Veterinary Internal Medicine
• NACDS-Insulin Chart-Page 2
• Treatment of Diabetes Mellitus in Dogs Using Isophane Insulin Penfills Thoresen SI, Lorenzen FH., 1998, Acta Veterinaria Scandanavica
• Insulin therapy for dogs and cats Dowling, Patricia, September 1995, Canadian Veterinary Journal