Characteristics of available insulin preparations

Read Also

Commercial insulin preparations differ with respect to the animal species from which they are obtained, their purity and solubility, and the time of onset and duration of their biologic action. As many as 17 different formulations of insulin are available in the United States.

a. Species of insulin

Human insulin is produced by recombinant DNA techniques (biosynthetic human insulin) as Humulin (Eli Lilly) and as Novolin (Novo Nordisk). It is dispensed as either regular (R), NPH (N), lente (L), or ultralente (U) formulations (Table 27-10). Four analogs of human insulin-three rapidly acting (insulin lispro, insulin aspart, insulin glulisine) and one very long-acting (insulin glargine)-have been approved by the FDA for clinical use (see below). A limited supply of monospecies pork insulin (Iletin II) remains available for use in certain patients who may benefit from the slightly more prolonged and sustained effect of animal insulin compared with human insulin. The cost of human insulin is slightly less than the cost of purified pork insulin.

b. Purity of insulin

"Purified" insulin is defined by FDA regulations as the degree of purity wherein proinsulin contamination is less than 10 ppm, whether extracted from animal pancreas or produced from biosynthetic proinsulin. All human insulin and pork insulin products of Novo Nordisk and Eli Lilly presently available contain less than 10 ppm of proinsulin and are labeled as "purified." These purified insulins seem to preserve their potency quite well, so that refrigeration is recommended but not crucial. During travel, reserve supplies of insulin can thus be readily transported for weeks without losing potency if protected from extremes of heat or cold.

c. Concentration of insulin

At present, insulins in the United States are available in a concentration of 100 units/mL (U100), and all are dispensed in 10-mL vials. With the popularity of "low-dose" (0.5- or 0.3-mL) disposable insulin syringes, U100 can be measured with acceptable accuracy in doses as low as 1-2 units. For use in rare cases of severe insulin resistance in which large quantities of insulin are required, U500 regular human insulin (Humulin R) is available from Eli Lilly.