Selective incretin/amylin combos
Single molecules engineered to hit four or more metabolic receptors at once — GLP-1, GIP, glucagon and amylin — chasing greater weight loss with better lean-mass retention and less nausea than any one pathway allows.
Also known as triple plus amylin quad agonists, next-gen polyagonists, quadruple receptor agonists, NA-931
Human trials — Studied in people, typically early phase or small — promising rather than proven.
The concept is validated: retatrutide's triple agonism reached roughly 24% weight loss in a randomised phase 2, and CagriSema showed that adding amylin to GLP-1 works as a co-formulation. The specific four-and-five-receptor molecules referenced here are in phase 1 or early phase 2 with fragmentary data, much of it presented as conference abstracts rather than peer-reviewed papers. Nothing in this sub-class has a published phase 3 result.
How it works
The logic behind polyagonism is dose-limiting toxicity. GLP-1 agonism produces nausea before it produces maximal weight loss; glucagon agonism raises energy expenditure but also hepatic glucose output and heart rate; amylin agonism produces satiety and preserves lean mass but is limited by its own nausea ceiling. A molecule with balanced partial agonism at several receptors can sit below each individual ceiling while summing the metabolic benefit. Retatrutide's triple-agonist phase 2 result of roughly 24% weight loss at 48 weeks established that adding pathways adds efficacy. The 2026 frontier is adding amylin as a fourth arm, either as a fixed-dose co-formulation in the CagriSema mould or as a genuine unimolecular quad. NA-931 takes a different route, combining IGF-1, GLP-1, GIP and glucagon receptor agonism in an orally dosed molecule with the explicit goal of avoiding lean-mass loss, and reported roughly 6.4% weight reduction over 28 days in early work. Preclinical quintuple agonists adding calcitonin have also been disclosed. The open questions are whether balanced partial agonism actually behaves additively in humans, and whether the safety surface of four simultaneous receptor systems is manageable.
Targets: GLP-1 receptor, GIP receptor, Glucagon receptor, Amylin/calcitonin receptor (AMY1-3, CTR), IGF-1 receptor (NA-931)
Dosing
| Protocol | Dose | Frequency | Route |
|---|---|---|---|
| No established human protocolNot applicable outside a trial. | — | typically once weekly in trial design | subcutaneous |
- · These are phase 1 and early phase 2 molecules. No dose has been published that a person could act on, and the whole point of a polyagonist is precisely calibrated receptor ratios that grey-market synthesis cannot reproduce. If a vendor is selling a 'quad agonist', they are selling you a guess about a structure that has not been publicly disclosed.
Titration
Every molecule in this class requires slow stepwise dose escalation over 12-20 weeks to manage nausea; the escalation schedule is drug-specific and is the single most important part of the protocol.
Cycling
Not established. Incretin-class agents in general are continuous therapy with rapid weight regain on discontinuation.
Pharmacology
- Half-life
- Engineered for once-weekly subcutaneous dosing in most programmes, using C18-C20 fatty acid albumin binding.
- Onset
- Appetite suppression within the first week; weight loss accrues over 36-72 weeks in trials of this class.
- Routes
- subcutaneous, oral
- Molecule
- Engineered multi-receptor polyagonist peptides and peptide-drug conjugates
Handling
- Diluent
- Bacteriostatic water
- Lyophilised
- Refrigerated for clinical-trial material.
- Reconstituted
- Refrigerated per trial protocol.
- Light sensitive
- Yes — keep it out of the light
Mixing
Not commercially available in any legitimate form. Research-chemical versions of undisclosed structures should be assumed to be something else entirely.
Side effects
- very commonNausea and vomiting— The dose-limiting effect for every molecule in this family, worse when arms are stacked poorly.
- commonElevated heart rate— Driven by the glucagon and GLP-1 arms; retatrutide showed dose-dependent heart rate increases.
- commonLean mass loss— The problem the amylin and IGF-1 arms are specifically intended to mitigate; whether they do in humans is unproven.
- uncommonHyperglycaemia from the glucagon arm— Glucagon raises hepatic glucose output; balance against the incretin arms is the entire design challenge.
Do not use if
- Personal or family history of medullary thyroid carcinoma or MEN2 - the standard class warning for GLP-1 and GIP agonists.
- History of pancreatitis.
- Pregnancy.
Combining it
- redundanttirzepatide — Overlapping receptor coverage; stacking a polyagonist onto an existing incretin is duplicating agonism at the same receptors with no way to know the effective total dose.
- redundantsemaglutide — Same problem — you cannot titrate what you cannot quantify.
What to monitor
- · Weight, waist circumference and body composition by DEXA if available.
- · Resting heart rate.
- · HbA1c and fasting glucose.
- · Lipase if abdominal pain develops.
Legal status
All investigational. None approved anywhere.
References
- Jastreboff et al. 2023, New England Journal of Medicine — retatrutide triple hormone receptor agonist phase 2 obesity trial (trial)
- ADA 2025 abstract 143-OR — NA-931 quadruple IGF-1/GLP-1/GIP/glucagon receptor agonist (trial)
Mechanism in depth
Pairing an incretin agonist with an amylin analogue, on the rationale that amylin acts through calcitonin and RAMP-based receptors rather than incretin receptors - so the two mechanisms add rather than overlap. Amylin signalling also appears to preserve lean mass better than incretin monotherapy, which is the emerging clinical argument for the combination.
What usually goes wrong
This is a category, not a compound, and the failure is treating it as one - the tolerability and efficacy of a specific pairing cannot be inferred from the concept. Combining two agents that both cause nausea and both slow gastric emptying compounds those effects, and titration has to be slower than for either alone.
Receptor targets
- Calcitonin receptor with RAMP1/2/3 (amylin arm) — Varies by analogue
Satiety through a non-incretin pathway
- GLP-1R and/or GIPR (incretin arm) — Varies
Glucose-dependent insulin secretion, gastric slowing, appetite suppression
Genuinely uncertain
- Trial data belongs to specific named combinations, not to the category.
- Long-term lean-mass preservation claims are still being established.
- Combining research-grade material outside a studied pairing has no supporting data at all.