NewNo. 013
Retatrutide
GLP-1 / GIP / glucagon triple receptor agonist
- Size
- 4 sizes
- HPLC
- 99.2%
- Lot
- 07022601
£139.99£3.50/mg
Options NewNo. 013
NewNo. 014
Retatrutide Pen
Synedica pre-filled pen: 40 mg retatrutide, with needles
- Size
- 40 mg pen
- HPLC
- 99.752%
- Lot
- 07022601
£159.99£4.00/mg
Peptides in this category act on the incretin and mitochondrial pathways that regulate energy balance. The GLP-1 family (semaglutide, tirzepatide and the investigational retatrutide) are the most searched compounds in the UK and, where licensed, are prescription-only medicines supplied by pharmacies; anything sold here is the unlicensed research form, listed only with legal advice. MOTS-c, a mitochondrial-derived peptide, is studied in rodent models of insulin sensitivity and exercise capacity. Retatrutide is stocked in two formats: a 40 mg lyophilised vial tested per lot with the certificate published, and the Synedica Retatrutide Pen, a sealed pre-filled 40 mg pen supplied with needles, the retatrutide in it from the same published lot. Both are held in UK stock and dispatched the same working day.
In brief: Weight and metabolic peptides are compounds acting on the incretin and glucagon receptors that regulate energy balance. ALTA PEPTIDES stocks retatrutide in two formats, a 40 mg lyophilised vial and the Synedica pre-filled 40 mg pen, in UK stock, with the certificates of analysis published for Retatrutide (lot 07022601) and Retatrutide Pen (lot 07022601, for the retatrutide loaded in the pen), dispatched the same working day before 1pm. It is an investigational compound supplied for laboratory research only, not a weight-loss product.
The weight and metabolic range compared
| Compound | Mechanism | Size | Price | Per mg | Certificate |
|---|---|---|---|---|---|
| RetatrutideGLP-1 / GIP / glucagon triple receptor agonist | Triple incretin/glucagon receptor agonist | 40 mg vial10 mg, 20 mg, 30 mg coming soon | £139.99 | £5.00/mg | Lot 07022601 (manufacturer certificate) |
| Retatrutide PenSynedica pre-filled pen: 40 mg retatrutide, with needles | Triple incretin/glucagon receptor agonist | Pre-filled pen, 40 mg | £159.99 | £4.00/mg | Lot 07022601 (supplier’s third-party report) |
What the research covers
Retatrutide (40 mg vial and Synedica pre-filled pen) is the compound here. Retatrutide (LY3437943) is a once-weekly triple agonist of the GLP-1, GIP and glucagon receptors under development by Eli Lilly. The phase 2 obesity trial published in the New England Journal of Medicine in 2023 reported a mean body-weight reduction of 24.2% at 48 weeks in the highest-dose arm, with gastrointestinal adverse events the most common; five phase 3 trials (four TRIUMPH obesity trials and one TRANSCEND type 2 diabetes trial) have since reported positive results, with up to 28.7% average weight loss, and Lilly plans to file with the FDA in early 2027. It has no marketing authorisation anywhere, which makes every vial or pen sold in the UK unlicensed and outside the trial programme. Our trial results and release date guide and comparison with tirzepatide cover the trial record in detail.
Searches for peptides for weight loss UK-wide mostly mean the licensed GLP-1 class: semaglutide (Wegovy, Ozempic) and tirzepatide (Mounjaro) are prescription-only medicines supplied by pharmacies, and we do not sell them. Retatrutide is the unlicensed research compound from the same class, and the GLP-1 explainer sets out how the three differ on the published record.
Vial or pen
Both listings contain the same synthetic retatrutide and the same 40 mg total. The 40 mg vial is a single lyophilised vial from a lot we publish the certificate for: powder to be reconstituted in the laboratory, and the cheaper of the two per milligram. The Synedica Retatrutide Pen is a third-party finished product: a sealed pre-filled multi-use pen already loaded with 40 mg of retatrutide, boxed with disposable needles and the manufacturer's leaflet, supplied as received. There is nothing to reconstitute and no diluent; the price is higher because it includes the device and the manufacturer's preparation. The retatrutide loaded in the pen is from the same lot as the 40 mg vial (lot 07022601), so the same published lot certificate covers the compound in both, while the device itself is the manufacturer's. Both are supplied for laboratory research only, and the comparison table above shows the price per milligram side by side.
Choosing between them
Retatrutide is the only compound in this category, in two formats (the 40 mg vial and the Synedica pre-filled pen), so the useful comparison is with related peptides elsewhere in the range. MOTS-c, in longevity and cellular, is the other metabolic peptide we stock: a mitochondrial-derived peptide studied in mice for AMPK activation and insulin sensitivity rather than incretin signalling, and the two are a common pairing in the stack builder. Tesamorelin, in growth hormone, is a GHRH analogue whose human trials measured visceral adipose tissue, a different axis again. Anyone comparing weight loss peptides UK vendors sell on price should use the retatrutide price comparison, which lists every UK listing per vial and per milligram.
Buying in the UK
Retatrutide is not a controlled substance in the UK and is legal to possess. It is an investigational medicine with no marketing authorisation anywhere, and the MHRA actively pursues unlawful supply of GLP-1-class compounds for human use, so it is listed here on written legal advice as a laboratory reagent for in-vitro research only; orders indicating an intended human use are refused.
Everything on this page is held in UK stock and dispatched the same working day before 1pm Monday to Friday by Royal Mail Tracked 48 (£4.95, free over £75) in plain packaging. Certificates: published for Retatrutide (lot 07022601) and Retatrutide Pen (lot 07022601, for the retatrutide loaded in the pen). That is the manufacturer's or supplier's paperwork published as received; ALTA's own independent test of each lot is added to the certificates page as it arrives. Retatrutide counts towards the automatic stack discount when ordered with another single-compound peptide: 10% off the peptide lines for two compounds, 15% for three, 20% for four or more, via the stack builder.
Questions
Licensed GLP-1 medicines are prescription-only and come from a pharmacy. Retatrutide, which is unlicensed everywhere, is legal to possess in the UK and is sold here as a laboratory reagent for research. It is not sold for human use, and orders that indicate otherwise are refused.
Retatrutide only, as a 40 mg lyophilised vial and as the Synedica Retatrutide Pen, a sealed pre-filled 40 mg pen from a named manufacturer with the lot certificate for the loaded retatrutide published. We do not sell semaglutide or tirzepatide, and we do not fill pens ourselves.
The same compound and the same 40 mg total. The vial is one 40 mg lyophilised vial, powder to be reconstituted in the laboratory, with its lot certificate published, and it is cheaper per milligram. The pen is a sealed Synedica pre-filled multi-use pen with the 40 mg already loaded, supplied with needles, at a higher price that includes the device; nothing to reconstitute. The retatrutide in the pen is from the same lot as the vial, so the same published lot certificate covers the compound in both. Both are research reagents only.
No. Mounjaro is tirzepatide, a licensed dual GLP-1 and GIP agonist. Retatrutide adds the glucagon receptor and has no licence anywhere; its published data come from Lilly's phase 2 trial, with phase 3 ongoing.
Retatrutide: the manufacturer's QC batch certificate for lot 07022601 is published on the certificates page, reporting purity 99.2% by HPLC and identity by mass spectrometry. The Retatrutide Pen is a sealed third-party pre-filled pen supplied as received (a Synedica pen already loaded with 40 mg of retatrutide, with needles); the retatrutide in it is from lot 07022601, the same lot as our 40 mg retatrutide vial, and the manufacturer's QC batch certificate for that lot is published on the certificates page, reporting purity 99.2% by HPLC and identity by mass spectrometry. The certificate is for the lot of compound the pen was loaded from; the filling and the device are the manufacturer's. ALTA's own independent third-party test of each lot is pending and is published on the same page as it arrives; no lot is described as independently tested until it is.
Guides for this category
- Retatrutide pen vs vial: what UK vendors actually sellA pre-filled retatrutide pen and a lyophilised retatrutide vial are different products in handling, stability, traceability and price per milligram, and who filled the pen matters more than the format. What each one is and how the two we supply compare.
- How to get retatrutide in the UK: what is legal, the trial results, the release date and how to check a vendorRetatrutide is an unlicensed investigational compound sold in the UK as a research reagent. Where that leaves a buyer legally, what separates a credible vendor from a risky one, and what the market charges.
- What is retatrutide? The triple-hormone peptide, explained simplyRetatrutide, often shortened to reta, is Eli Lilly's experimental once-weekly peptide that acts on three appetite and metabolism hormones at once: GLP-1, GIP and glucagon. In its largest phase 3 trial, people on the highest amount lost 28.3% of their body weight on average over 80 weeks. What it is, how it works, the results, the side effects and where it stands.
- How to store peptides, and how long lyophilised peptides last at room temperatureTemperatures, light, moisture, freeze-thaw cycles and aliquoting: what actually determines how long a peptide stays within specification.
- How to read a peptide certificate of analysisHPLC purity, mass spec identity, net peptide content and endotoxin: what each line on a COA means and which ones sellers tend to leave out.
- Are peptides legal in the UK? Research peptides and the law explainedWhich laws actually apply to research peptides in the UK, what a supplier can and cannot do, and why research use only is a legal condition rather than a slogan.
- Retatrutide vs tirzepatide vs semaglutide: receptors, licences and trial resultsOne licensed GLP-1 agonist, one licensed dual agonist, one unlicensed triple agonist: how the three differ on the published record.
Other research areas
- Recovery & Repair: Peptides studied in tissue, tendon and gut models.
- Copper & Skin: GHK-Cu and copper-peptide stacks studied in dermal and wound models.
- Brain & Focus: Nootropic peptides from the Russian literature, supplied as lyophilised powder.
- Growth Hormone: GHRH analogues and secretagogues studied for pulsatile GH release.
- Longevity & Cellular: Peptides studied in ageing, telomere and mitochondrial research.
- Libido & Tanning: Melanocortin receptor agonists.
- Sleep: Delta sleep-inducing peptide.
- Myostatin Antibodies: Research-grade antibodies against myostatin, activin A and the activin type II receptors.
- Water & Accessories: Bacteriostatic water, syringes and swabs for reconstitution.
Related: certificates of analysis, peptide calculator, build a stack, FAQ, all research peptides.
Research use only
Every product on this site is sold as a laboratory reagent for in-vitro and analytical research. Not for human or veterinary use, not a medicine, not a supplement. By ordering you confirm you are 18 or over and accept our research use policy.