Answer to Question #259558 in General Chemistry for Pogi

Question

Why is insulin administered by injection instead of taken in tablet form?

Answer 1

Insulin needs to reach certain cells in the body to induce them to remove glucose from the circulation. Therefore insulin needs to be inside the body, not inside the intestines.

Being a peptide (sort of a small protein), insulin will be digested in the intestines. Therefore its constituent amino acids will be used as food, instead of for blood glucose level regulation. Therefore It is not effective when administered orally.