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ForumsPharmacology & MechanismsPeptide degradation pathways — DPP-4 and NEP 24.11 cleavage sites

Peptide degradation pathways — DPP-4 and NEP 24.11 cleavage sites

PeptideChemSF Sun, May 31, 2026 at 12:39 PM 18 replies 345 viewsPage 1 of 4
PeptideChemSF
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May 31, 2026 at 12:39 PM#1

Putting this up for argument rather than for agreement. I have read it twice and I am still not certain what it supports.

The mechanism is more central than most summaries suggest. Receptor agonism in the arcuate nucleus activates POMC neurons and inhibits AgRP/NPY signalling, and the downstream MC4R pathway is the same one disrupted in monogenic obesity — convergent genetic evidence that the target is the right one. Peripherally there is glucose-dependent insulin secretion, glucagon suppression and delayed gastric emptying, but the gastric component largely adapts over months while the central effect persists, which is why the durable effect is appetite rather than fullness.

Where I think it is weakest: the comparator does most of the work in how this gets reported, and it is not the comparator most people think they are citing.

The question I want answered is which effects tachyphylax and which persist, because the answer explains why tolerability improves while the appetite effect keeps working. If the honest answer is that nobody knows, that is a useful answer and I would rather have it.

Note on sourcing:
Figures above are from the primary publication rather than the press summary. If a number here disagrees with one you have, post yours and we will work out which of us is reading a secondary source.
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TirzTom
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May 31, 2026 at 12:50 PM#2
PeptideChemSF said:
The mechanism is more central than most summaries suggest.

Amycretin (AMY/GLP-1 dual agonist) emerging data relevant to the pharmacology: Phase 1 showed -13.1% body weight at only 12 weeks, the fastest trajectory ever seen for an anti-obesity agent[1].

Amylin receptor agonism enhances satiety signaling through the area postrema and reduces glucagon secretion. Combined with GLP-1R agonism, this dual mechanism may produce even greater efficacy than current agents.

Early-stage data — interpret with caution. But the trajectory is extraordinary.

References:
[1] Novo Nordisk investor presentation, September 2023.
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JessicaH_TX
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May 31, 2026 at 1:01 PM#3
PeptideChemSF said:
The mechanism is more central than most summaries suggest.

Pushing back on PeptideChemSF here. The pharmacokinetics explain nearly every practical question asked here. Albumin binding above 99% slows clearance enough to make weekly dosing possible; a terminal half-life near a week means four to five weeks to steady state and therefore a four-week titration interval; subcutaneous bioavailability around 89% means injection site barely matters. Those three facts answer most timing questions before they are asked.

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NurseKim_ATL
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May 31, 2026 at 1:12 PM#4
JessicaH_TX said:
The pharmacokinetics explain nearly every practical question asked here.

Receptor pharmacology relevant to the pharmacology: semaglutide is a GLP-1R agonist with a C-18 fatty acid chain that enables albumin binding (>99%), creating a depot effect with a ~168-hour half-life enabling weekly dosing[1].

Tirzepatide is a dual GIP/GLP-1R agonist with higher GIP affinity (5:1 GIP:GLP-1 potency ratio). The GIP component may enhance beta-cell function and adipocyte lipid metabolism beyond what GLP-1 alone achieves.

For the pharmacology, the pharmacology explains the clinical differences between these agents.

References:
[1] Lau J, et al. J Med Chem. 2015;58(18):7370-7380.
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Dr.DermMIA
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May 31, 2026 at 2:13 PM#5
TirzTom said:
Amycretin (AMY/GLP-1 dual agonist) emerging data relevant to the pharmacology: Phase 1 showed -13.1% body weight at only 12 weeks, the fastest…

Second this. I had assumed I was the exception until I read this.

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