Retatrutide Peptide UK
Quick Answer
Retatrutide (LY3437943) is available in the UK as a research-grade lyophilised peptide for in vitro laboratory use. It is not a licensed medicine and has not received MHRA approval. UK researchers can legally purchase it as a research chemical. Velox Peptides supplies retatrutide with HPLC purity certificates (≥99%), CoA documentation, and next-day UK delivery.
What Is Retatrutide?
Compound Profile
- CAS Number
- 2381609-56-7
- INN / Identifier
- Retatrutide (LY3437943)
- Peptide class
- Glucagon-derived 36-mer; fatty acid conjugated
- Receptor targets
- GLP-1R, GIPR, GcgR (triple agonist)
- Molecular weight
- ~4,813 Da
- Developer
- Eli Lilly and Company
- Current status
- Phase 3 clinical trials (not MHRA-approved)
- Research form
- Lyophilised powder, ≥99% HPLC purity
Retatrutide is a synthetic peptide engineered to simultaneously activate three hormone receptors: the glucagon-like peptide-1 receptor (GLP-1R), the glucose-dependent insulinotropic polypeptide receptor (GIPR), and the glucagon receptor (GcgR). This triple mechanism distinguishes it from approved GLP-1 agents such as semaglutide (Ozempic/Wegovy) and the dual GLP-1/GIP agonist tirzepatide (Mounjaro).
In Phase 2 research published in the New England Journal of Medicine (2023), participants receiving retatrutide 12 mg weekly demonstrated a mean weight reduction of approximately 22.1% over 48 weeks — a result that attracted significant scientific attention and drove strong search interest from UK researchers.
UK Regulatory Status
Understanding the regulatory position of retatrutide in the UK is critical for any researcher intending to acquire or work with the compound.
MHRA Position
Retatrutide is not licensed as a medicinal product by the Medicines and Healthcare products Regulatory Agency (MHRA). It is in Phase 3 clinical development under Eli Lilly's oversight. No marketing authorisation has been granted. It cannot legally be administered to humans in the UK outside of an authorised clinical trial.
Is It Legal to Buy Retatrutide in the UK?
Yes, under the correct conditions. Research chemicals — including peptides such as retatrutide — may be purchased and possessed in the UK for genuine in vitro laboratory research purposes. The compound must not be:
- Intended for human or veterinary administration
- Sold or supplied as a medicinal product without a licence
- Used in regulated clinical research without appropriate ethics and regulatory approval
Velox Peptides sells retatrutide exclusively for in vitro research use and requires purchasers to confirm research intent at checkout. All sales are subject to our Research Use Policy and MHRA Statement.
Important: This page is an informational research guide. Nothing here constitutes medical advice. Retatrutide is not approved for human use in the UK. If you are seeking treatment for obesity or metabolic conditions, please consult a qualified healthcare professional.
Purity Standards for UK Research
Not all research peptides meet the quality standards required for reproducible in vitro work. When sourcing retatrutide in the UK, researchers should require the following documentation:
| Quality Parameter | Minimum Standard | Velox Standard |
|---|---|---|
| HPLC Purity | ≥95% | ≥99% |
| Mass Spectrometry | Sequence confirmed | MS verified, reported on CoA |
| Certificate of Analysis | Batch-specific | Batch-specific, publicly archived |
| Storage form | Lyophilised powder | Lyophilised, −20 °C shipped |
| Endotoxin testing | Not always provided | Available on request |
Velox Peptides publishes batch-specific Certificates of Analysis for all compounds, accessible via the CoA Library. Each CoA reports the chromatographic purity trace, molecular mass confirmation, and batch number.
Storage and Handling
Lyophilised Powder (Unopened)
Store at −20 °C in the dark. Properly stored lyophilised retatrutide is stable for up to 24 months. Do not expose to repeated temperature fluctuations.
Reconstituted Solution
Reconstitute using sterile bacteriostatic water (0.9% benzyl alcohol). Working aliquots in bacteriostatic water can be stored at 4 °C for up to 4 weeks. For longer storage, prepare small aliquots and store at −20 °C; avoid more than two freeze-thaw cycles.
Reconstitution Reference
For step-by-step reconstitution guidance, see the Peptide Reconstitution Guide. For bacteriostatic water sourcing, see Bacteriostatic Water Explained.
Published Research Overview
Retatrutide has a substantial published research record across preclinical and clinical stages:
Preclinical: Triple Agonism in Obese Rodent Models
Coskun et al. demonstrated that retatrutide produced superior weight loss and metabolic improvements over GLP-1 and dual GLP-1/GIP agonists in diet-induced obese mice and non-human primates, establishing the preclinical rationale for human trials.
Phase 1: Safety and Pharmacokinetics
Urva et al. published the Phase 1 results for LY3437943, confirming a weekly dosing pharmacokinetic profile, dose-proportional exposure, and an acceptable safety profile in healthy volunteers and participants with type 2 diabetes.
Phase 2: Weight Reduction Outcomes
Jastreboff et al. reported 48-week results from the Phase 2 NEJM trial. The 12 mg retatrutide cohort achieved a mean 22.1% reduction in body weight, with dose-dependent efficacy across all treatment arms. Phase 3 recruitment is ongoing.
For a full breakdown of the clinical research programme with methodology and endpoints, see the Retatrutide Clinical Research Guide.
Retatrutide vs Other UK Research Peptides
UK researchers frequently compare retatrutide with other metabolic-pathway peptides available as research reagents. Key distinctions:
| Compound | Receptor Targets | Trial Stage | Available in UK |
|---|---|---|---|
| Retatrutide | GLP-1R + GIPR + GcgR | Phase 3 | Yes (research) |
| Semaglutide (Ozempic) | GLP-1R only | Licensed | Licensed medicine only |
| Tirzepatide (Mounjaro) | GLP-1R + GIPR | Licensed | Licensed medicine only |
Because semaglutide and tirzepatide are licensed medicines, they cannot be purchased as research chemicals in the UK. Retatrutide, being in clinical development without a licence, is available as a research peptide and represents a unique opportunity to study triple receptor agonism in in vitro models.
Source Retatrutide in the UK
Velox Peptides supplies research-grade retatrutide (LY3437943) with HPLC purity ≥99%, batch-specific CoA, and tracked UK delivery. Lyophilised powder, suitable for in vitro reconstitution.
View Retatrutide →Frequently Asked Questions
Is retatrutide legal in the UK?
Retatrutide is not a licensed medicine in the UK and has not received MHRA approval. It is legal to purchase and possess as a research chemical for in vitro laboratory use. It may not be administered to humans outside of an authorised clinical trial.
Where can UK researchers buy retatrutide?
UK researchers can source retatrutide from specialist research peptide suppliers. Velox Peptides supplies retatrutide lyophilised powder with HPLC purity certificates (≥99%) and ships within the UK.
What purity should research-grade retatrutide be?
Research-grade retatrutide should be verified at ≥99% purity by HPLC. Each batch should have a Certificate of Analysis confirming purity, sequence identity, and mass spectrometry validation.
What is retatrutide used for in research?
In research settings, retatrutide is studied as a triple receptor agonist at GLP-1, GIP, and glucagon receptors. Published preclinical and clinical data have examined its effects on body weight, glucose metabolism, and lipid profiles.
Is retatrutide available in the UK as a medicine?
No. As of 2026, retatrutide (LY3437943) is in Phase 3 clinical trials and has not received marketing authorisation from the MHRA. It is not available as a licensed medicine in the UK.
How should retatrutide be stored?
Lyophilised retatrutide powder should be stored at −20 °C in the dark. Once reconstituted in bacteriostatic water, working aliquots should be kept at 4 °C and used within 4 weeks. Avoid repeated freeze-thaw cycles.
What is the molecular weight of retatrutide?
Retatrutide (LY3437943) has a molecular weight of approximately 4,813 Da. It is a 36-amino-acid peptide with fatty-acid conjugation enabling simultaneous GLP-1, GIP, and glucagon receptor agonism.
How does retatrutide differ from tirzepatide and semaglutide?
Semaglutide is a selective GLP-1 receptor agonist. Tirzepatide is a dual GLP-1/GIP agonist. Retatrutide adds glucagon receptor agonism, creating a triple agonist. Phase 2 data showed greater mean weight reduction than either comparator.
References
- Coskun T, et al. Cell Metab. 2022;35(3):571–584. PMID 35108511
- Urva S, et al. Lancet. 2022;400(10361):1869–1881. PMID 36356631
- Jastreboff AM, et al. N Engl J Med. 2023;389(6):514–526. PMID 37366315