Short/rapid-acting insulins administration

The hydrogen ion concentration of insulin preparations influences their stability, solubility and immunogenicity. After i.m. administration, short-acting insulin is absorbed about twice as rapidly as after s.c. injection, and therefore the i.m. route is used in the management of ketoacidosis in those cases where continuous i.v. infusion cannot be established. After s.c. injection, absorption of short-acting insulin varies considerably depending in particular on the site of injection. Patient-to-patient variability is as great with these preparations as the variations in the... 

Insulin preparations that are commercially available differ in their relative onset of action, maximal activity, and duration of action. Conjugation of the insulin molecule with either zinc or protamine, or both, will convert the normally rapidly absorbed parenterally administered insulin to a preparation with a more prolonged duration of action. The various formulations of insulin are usually classified as short acting (0.5 to 14 h), intermediate acting (1 to 28 h), and long acting (4 to 36 h). The duration of action can vary, however, depending on injection volume, injection site, and blood flow at the site of administration. 

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