Oral GLP-1 receptor agonists (like semaglutide tablets) work in the same way as injectable GLP-1 drugs, but with some differences in absorption and delivery. Let me break it down step by step:
Mechanism of Action (What GLP-1 drugs do in the body)
GLP-1 = Glucagon-Like Peptide-1, a natural hormone released in your gut after eating. It helps regulate blood sugar and appetite.
When you take an oral GLP-1 drug:
- Stimulates insulin release
- When blood glucose is high, GLP-1 drugs make your pancreas release more insulin.
- This lowers post-meal blood sugar levels.
- Suppresses glucagon
- Glucagon normally tells your liver to release glucose.
- GLP-1 drugs reduce glucagon, preventing unnecessary sugar release.
- Slows gastric emptying
- Food moves more slowly from the stomach into the intestine.
- This reduces blood sugar spikes after meals.
- Acts on the brain
- Increases feelings of fullness.
- Decreases hunger and cravings → helps with weight loss.
Why oral GLP-1 is special (vs injections)
Normally, proteins like GLP-1 would be destroyed in the stomach.
Oral GLP-1 drugs use a special absorption enhancer (SNAC – sodium N-[8-(2-hydroxybenzoyl) amino] caprylate):
- SNAC protects the drug from stomach acid.
- SNAC temporarily increases permeability of the stomach lining, allowing the drug to pass into the bloodstream.
- The drug then travels to GLP-1 receptors in the pancreas, brain, and gut, just like the injection.
Net Effects
- Better blood sugar control (especially after meals).
- Significant weight reduction by reducing appetite and calorie intake.
- Protection for the heart and kidneys (shown in some clinical trials).
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