GLP Science covers the receptor biology and mechanism content behind the GLP-1 drug class — not the drugs themselves, but the logic that produced them. Why does activating GLP-1R suppress appetite? Why did adding a second receptor break the efficacy ceiling? Why does glucagon belong in an obesity drug at all? These are the posts that answer those questions.
The class evolved through a clear progression: single receptor agonism proved the mechanism and defined the ceiling. Dual agonism broke that ceiling by recruiting GIPR or GCGR alongside GLP-1R. Triple agonism pushed to all three simultaneously. Oral non-peptide drugs re-solved the delivery problem at the molecular level. And emerging modalities are testing amylin pathways, GIP receptor inversion, and dosing intervals that weren't previously achievable. Each step reflects a specific mechanistic insight about what was limiting the prior generation.
Understanding this progression matters because it determines which drugs to compare to each other, what the efficacy data actually measures, and why different drugs are built for different patient populations. The GI side effects from semaglutide and tirzepatide are not an accident — they're a consequence of how GLP-1R works in the gut. The liver benefit from survodutide is not incidental weight loss — it's a direct glucagon receptor effect. The mechanism is the map.
For the drug profiles themselves — approved formulations, trial data, dosing, development status — see the GLP Dex series.
The five posts in this series
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Single Agonists — One receptor, multiple effects. How GLP-1R works, why the ~15% weight loss ceiling exists, and what it means that it held for a decade before dual agonism broke it.
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Dual Agonists — Two mechanistic branches: GLP-1/GIP (appetite amplification) and GLP-1/glucagon (energy expenditure and liver targeting). Why they work differently and where each branch has the stronger case.
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Triple Agonists — GLP-1R, GIPR, and GCGR simultaneously. What each receptor adds that the others don't, and why 24.2% weight loss in Phase 2 changes the surgical comparison.
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Oral GLP-1 — Why peptide GLP-1 drugs require injections, what non-peptide small molecules solve at the molecular level, and what the manufacturing cost difference means for access.
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Emerging Modalities — Amylin as a second satiety circuit, GIPR antagonism vs agonism, ultra-long half-life engineering, and a GLP-1-independent pathway for intolerant patients.