Medications and Drugs

GENERIC NAME: insulin

BRAND NAME: various

DRUG CLASS AND MECHANISM: Insulin is a naturally-occurring hormone secreted by the pancreas. Insulin is required by the cells of the body in order for them to remove and use glucose from the blood. From glucose the cells produce the energy that they need to carry out their functions. Researchers first gave an active extract of the pancreas containing insulin to a young diabetic patient in 1922, and the FDA first approved insulin in 1939. Currently, insulin used for treatment is derived from beef and pork pancreas as well as recombinant (human) technology. The first recombinant human insulin was approved by the FDA in 1982.

Patients with diabetes mellitus have an inability to take up and use glucose from the blood, and, as a result, the glucose level in the blood rises. In type 1 diabetes, the pancreas cannot produce enough insulin. Therefore, insulin therapy is needed. In type 2 diabetes, patients produce insulin, but cells throughout the body do not respond normally to the insulin. Nevertheless, insulin also may be used in type 2 diabetes to overcome the resistance of the cells to insulin. By increasing the uptake of glucose by cells and reducing the concentration of glucose in the blood, insulin prevents or reduces the long-term complications of diabetes, including damage to the blood vessels, eyes, kidneys, and nerves. Insulin is administered by injection under the skin (subcutaneously). The subcutaneous tissue of the abdomen is preferred because absorption of the insulin is more consistent from this location than subcutaneous tissues in other locations.

Regular (rapid onset of action, short duration of action) and NPH (slower onset of action, longer duration of action) human insulin are the most commonly-used preparations. Regular insulin has an onset of action (begins to reduce blood sugar) within 30 minutes of injection, reaches a peak effect at 1-3 hours, and has effects that last 6-8 hours.

NPH insulin is an insulin with an intermediate duration of action. It has an onset of action starting about 2 hours following injection. It has a peak effect 4-12 hours after injection, and a duration of action of 18-26 hours.

Lente insulin also is an insulin with an intermediate duration of action. It has an onset of action 2-4 hours after injection, a peak activity 6-12 hours after injection, and a duration of action of 18 to 26 hours. Ultralente insulin is a long-acting insulin with an onset of action 4-8 hours after injection, a peak effect 10-30 hours after injection, and a duration of action of more than 36 hours.

An ultra rapid-acting insulin, insulin lispro is a chemically-modified, natural insulin. It was approved by the FDA in June, 1996. As compared to regular insulin, insulin lispro has a more rapid onset of action, an earlier peak effect, and a shorter duration of action. It reaches peak activity 0.5-2.5 hours after injection. Therefore, insulin lispro should be injected 15 minutes before a meal as compared to regular insulin which is injected 30-60 minutes before a meal.

Insulin aspart and insulin glargine are both human insulin that have had their chemical composition slightly altered. The chemical changes provide insulin aspart with a faster onset of action (20 minutes) and a shorter duration of action (3-5 hours) than regular human insulin. It reaches peak activity 1-3 hours after injection. Insulin glargine has a slower onset of action (70 minutes) and a longer duration of action (24 hours) than regular human insulin. Its activity does not peak.

GENERIC: no

PRESCRIPTION: yes

PREPARATIONS: Insulin comes in three different forms-vials, prefilled syringes, and cartridges. The cartridges are to be used in a pen-like device that simplifies injection. Human recombinant insulin, insulin lispro, insulin aspart, and insulin glargine are the commonly-used insulins. Beef and pork insulin are infrequently used. Regular human insulin (Novolin R, Humulin R) is available in vials, cartridges, and prefilled syringes.

NPH human insulin (Novolin N, Humulin N) is available in vials, cartridges and prefilled syringes. A mixture of 70% NPH human insulin and 30% regular human insulin (Novolin 70/30, Humulin 70/30) is available in vials, cartridges and pre-filled syringes.

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