endogenous
Pronunciation: IN-su-lin

What it isPancreatic beta-cell hormone acting at the insulin receptor tyrosine kinase.
Why this oneEvery insulin product in the library is a modification of this molecule, altered for onset and duration rather than for a different target.
What limits itEndogenous secretion is portal and pulsatile, so injected insulin never reproduces the physiologic hepatic-to-peripheral gradient.
NO BOXED WARNINGS
Defining liabilityDose-dependent potentially fatal hypoglycemia