History
Hans Christian Hagedorn (1888–1971) and August Krogh (1874–1949) obtained the rights for insulin from Banting and Best in Toronto, Canada. In 1923 they formed Nordisk Insulinlaboratorium, and in 1926 with August Kongsted he obtained a Danish Royal Charter as a non-profit foundation.
In 1936, Hagedorn and B. Norman Jensen discovered that the effects of injected insulin could be prolonged by the addition of protamine obtained from the "milt" or semen of river trout. The insulin would be added to the protamine, but the solution would have to be brought to pH 7 for injection. Canada later produced bok insulin, a mixture of zinc, protamine and porcine insulin. This mixture only needed to be shaken before injection.
In 1946, Nordisk was able to form crystals of protamine and insulin and marketed it in 1950 as NPH insulin. NPH insulin has the advantage that it can be mixed with an insulin that has a faster onset to complement its longer lasting action, which is the primary reason NPH remains on the market today, because manufacturers sell a variety of premixed insulin formulations. However, numerous medical studies have suggested that NPH has one of the least consistent absorption rates when injected subcutaneously, and a majority of head-to-head comparisons with Lente insulin usually found Lente provided superior glycemic control.
Eventually all animal insulins made by Novo Nordisk were replaced by synthetic, recombinant 'human' insulin. Synthetic 'human' insulin is also complexed with protamine to form NPH.
NPH insulin is cloudy and has an onset of 3–4 hours. Its peak is 4–9 hours and its duration is about 15 hours.
Read more about this topic: NPH Insulin
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