Humulin is synthesized in a special non-disease-producing special laboratory strain of Escherichia coli bacteria that has been genetically altered by the addition of the gene for human insulin production.
Humulin R consists of zinc-insulin crystals dissolved in a clear fluid. Humulin R has nothing added to change the speed or length of its action. It takes effect rapidly and has a relatively short duration of activity (4 to 12 hours) as compared with other insulins.
Humulin N 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 insulin.
Humulin L is an amorphous and crystalline suspension of human insulin with a slower onset and a longer duration of activity (up to 24 hours) than regular insulin.
Humulin U is a crystalline suspension of human insulin with zinc providing a slower onset and a longer and less intense duration of activity (up to 28 hours) than regular insulin or the intermediate-acting insulins (NPH and Lente).
Humulin 50/50 is a mixture of 50% Human Insulin Isophane Suspension and 50% Human Insulin Injection. It is an intermediate-acting insulin combined with the more rapid onset of action than regular insulin. The duration of activity may last up to 24 hours following injection.
Humulin 70/30 is a mixture of 70% Human Insulin Isophane Suspension and 30% Human Insulin Injection. It is an intermediate-acting insulin combined with the more rapid onset of action of regular insulin. The duration of activity may last up to 24 hours following injection.
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 preparation, the duration of action of all forms of Humulin is dependent on dose, site of injection, blood supply, temperature, and physical activity. Humulin is a sterile solution and is for subcutaneous injection. It should not be used intravenously or intramuscularly. The concentration of all forms of Humulin is 100 units/ml (U-100).
