Oral insulin exhibited early, enhanced pharmacokinetic and pharmacodynamic responses compared with subcutaneous injection of regular human insulin, report Christoph Kapitza (Profil Institut für Stoffwechselforschung GmbH, Neuss, Germany) and colleagues.
Gastrointestinal absorption of oral insulin is hampered by factors such as enzymatic degradation and lack of permeation through epithelial cells, say the researchers.
They tested the value of combining human insulin with the novel drug-carrier molecule monosodium N-(4-chlorosalicyloyl)-4-aminobutyrate (4-CNAB) to facilitate gastrointestinal absorption in a single-center, open-label randomized study.
The proof-of-concept research included 10 men who had been diagnosed with Type 2 diabetes for over a year who were not treated with insulin therapy.
Participants underwent an overnight fast before receiving two capsules that each contained 150 U of oral insulin plus 200 mg 4-CNAB, or a subcutaneous injection for 15 U of regular human insulin on two separate occasions separated by up to 20 days.Maximum plasma insulin concentration was significantly greater with oral administration than subcutaneous injection, at a mean of 93 versus 33 µU/ml. Oral insulin also had a faster onset of action, with a corresponding area under the curve for glucose infusion rates in the first hour of 173 versus 27 mg/kg.
Mean insulin concentration and glucose infusion rate returned to baseline within 3 hours of oral insulin administration. A mean of just 7%was absorbed in the 2 hours following oral insulin administration.
Reporting in the journal Diabetes Care, the team suggests: “The fast pharmacokinetic and metabolic time-profiles of [oral insulin] observed in this study may be advantageous in patients with Type 2 diabetes by restoring normal first phase insulin secretion and potentially leading to an improvement in glycemic control.”
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