Intermediate-Acting Insulins

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Intermediate-Acting Insulins   top of page

Insulin NPH  (Novolin® N, Humulin® N)  

Insulin NPH   (Novolin® N, Humulin® N)  top of page

1- 2 hours
4-12 hours
14 - 24 hours (up to 24 hours)
Comments: Human Insulin Isophane Suspension. Cloudy/ milky suspension of human insulin with protamine and zinc.   
NPH + Aspart (Novolog ®): Compatible - NovoLog should be drawn into the syringe first. The injection should be made immediately after mixing.   

NPH + Lispro (Humalog ®): Compatible - Humalog should be drawn into the syringe first. The injection should be made immediately after mixing.   

NPH +Regular insulin: Always draw the Regular (clear) insulin into the syringe first.

Phosphate-buffered insulins ( NPH insulin) should NOT be mixed with lente insulins. Zinc phosphate may precipitate, and the longer-acting insulin will convert to a short-acting insulin to an unpredictable extent.  Currently available NPH and short-acting insulin formulations when mixed may be used immediately or stored for future use.

Humulin N [Human insulin (rDNA origin) isophane suspension] is a crystalline suspension of human insulin with protamine and zinc providing an intermediate-acting insulin with a slower onset of action and a longer duration of activity (up to 24 hours) than that of Regular human insulin. The time course of action of any insulin may vary considerably in different individuals or at different times in the same individual. As with all insulin preparations, the duration of action of Humulin N is dependent on dose, site of injection, blood supply, temperature, and physical activity. Humulin N is a sterile suspension and is for subcutaneous injection only. It should not be used intravenously or intramuscularly. The concentration of Humulin N is 100 units/mL (U–100).

Novolin N InnoLet
It is a cloudy or milky suspension of human insulin with protamine and zinc. The insulin substance (the cloudy material) settles at the bottom of the insulin reservoir, therefore, the Novolin N InnoLet must be rotated up and down so that the contents are uniformly mixed before a dose is given. Novolin N has an intermediate duration of action. The effect of Novolin N begins approximately 1.5 hours after injection. The effect is maximal between 4 and 12 hours. The full duration of action may last up to 24 hours after injection.


National Institutes of Health, U.S. National Library of Medicine, DailyMed Database.
Provides access to the latest drug monographs submitted to the Food and Drug Administration (FDA). Please review the latest applicable package insert for additional information and possible updates.  A local search option of this data can be found here.


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