How to Get Retatrutide: Buy Research Peptide in High Purity
Dr. Sieglinde Klaus
Scientific Editorial Team — Bergdorf Bioscience
Dr. Sieglinde Klaus
Scientific Editorial Team — Bergdorf Bioscience
Retatrutide (LY3437943) is the world's first triple agonist that simultaneously activates the GLP-1, GIP, and glucagon receptors. If you are looking for where to get retatrutide for sale as a research peptide, this guide covers everything you need to know about sourcing, quality criteria, and the scientific background of this groundbreaking compound.
Retatrutide is a synthetic 36-amino-acid peptide developed by Eli Lilly as a unimolecular triagonist. Unlike dual agonists such as tirzepatide, which target only GLP-1 and GIP receptors, retatrutide additionally activates the glucagon receptor (GCGR). This triple receptor binding opens a broad research spectrum: the GLP-1 component promotes glucose-dependent insulin secretion and slows gastric emptying; the GIP component improves insulin sensitivity; and the glucagon component increases resting energy expenditure through hepatic lipolysis and thermogenic effects. In the Phase 2 study by Jastreboff et al., 2023, a mean weight reduction of up to 24.2% over 48 weeks was observed – a result that surpasses all previous pharmacological approaches. Retatrutide is not approved and remains exclusively in the clinical research phase.
Retatrutide is available as a research chemical from specialized peptide suppliers. When purchasing, researchers should look for: documented purity of at least 99% (confirmed by HPLC and mass spectrometry analyses), an included Certificate of Analysis (CoA) per batch, GMP-compliant manufacturing conditions, and temperature-controlled shipping, as peptides are sensitive to heat. Bergdorf Bioscience offers retatrutide in various dosages from 10 mg to 50 mg, each batch with CoA and a purity of ≥99%. Shipping is cold-chain to ensure the stability of the lyophilized powder. Order Retatrutide now. It is important to emphasize that retatrutide is intended exclusively for research purposes and is not approved for human consumption.
For research, retatrutide is available as lyophilized powder in various vial sizes. Bergdorf Bioscience offers the following variants: 10 mg (from €112.99), 15 mg (from €144.99), 20 mg (from €216.99), 30 mg (from €235.99), and 50 mg (from €324.99). For longer research series, 2-packs and 3-packs with volume discounts are available. In clinical studies, dosages from 1 mg to 12 mg per week were investigated, with the highest efficacy data achieved at 8 mg and 12 mg (Jastreboff et al., 2023). The choice of vial size depends on the research protocol; our Retatrutide dosage calculator can help with needs assessment.
The mechanism of action of retatrutide is based on the simultaneous activation of three metabolically relevant receptors. GLP-1 receptor agonism enhances insulin secretion in a glucose-dependent manner and inhibits glucagon release, leading to improved glycemic control. GIP receptor activation works additively with GLP-1 and improves insulin sensitivity in adipose tissue. The third pillar – glucagon receptor agonism – is unique: it stimulates hepatic lipid oxidation and increases energy expenditure, an effect absent in dual agonists. Structurally, the half-life is extended through a fatty acid linkage via a linker to a lysine residue, enabling albumin binding and extending the plasma half-life to approximately 6 days (Coskun et al., 2022). At position 2 sits an alpha-aminoisobutyric acid (Aib) that protects the peptide from degradation by dipeptidyl peptidase-4 (DPP-4).
The evidence base for retatrutide is remarkably robust for a research peptide. The Phase 2 study (NEJM, 2023) with 338 participants showed dose-dependent weight reductions: 24.2% at 12 mg over 48 weeks versus 2.1% under placebo (Jastreboff et al., 2023). In December 2025, the results of the Phase 3 study TRIUMPH-4 were published: at the 12 mg dose, mean weight loss was 28.7% after 68 weeks, averaging 32.3 kg. In parallel, a Phase 2a study investigated the effect on metabolic dysfunction-associated steatotic liver disease (MASLD): at 12 mg, liver fat content was reduced by 86%, and 93% of participants normalized their liver fat to below 5% (Sanyal et al., 2024). The side effect profile is comparable to other incretin-based therapies; gastrointestinal complaints occurred mainly during the dose escalation phase.
The stability of retatrutide depends significantly on correct storage. As lyophilized powder, it should be kept at 2 to 8 °C in the refrigerator; for long-term storage over several months, a temperature of −20 °C or lower is recommended. Direct sunlight and repeated freeze-thaw cycles must be avoided. For reconstitution, sterile bacteriostatic water is used: the water is slowly injected along the vial wall, not sprayed directly onto the lyophilisate, and dissolved by gentle swirling. After reconstitution, the solution must be stored at 2 to 8 °C and used within 28 days. Using bacteriostatic water (with 0.9% benzyl alcohol) instead of pure sterile water significantly extends the shelf life of the reconstituted solution.
For reliable research results, a peptide purity of at least 98%, ideally 99% or higher, is critical. Purity is standardly determined by high-performance liquid chromatography (HPLC) and confirmed by mass spectrometry (MS). A reputable Certificate of Analysis (CoA) contains: HPLC purity as a percentage, the measured molecular weight (approximately 4,200 Da for retatrutide), the amino acid sequence, and the batch number. At Bergdorf Bioscience, each batch is delivered with an individual CoA documenting purity of ≥99%. Impurities such as trifluoroacetic acid (TFA) salts, residual solvents, or misfolded peptides can distort research results and should be excluded through quality documentation.
The key difference lies in receptor selectivity: semaglutide is a pure GLP-1 agonist, tirzepatide is a dual GLP-1/GIP agonist, and retatrutide is the only clinically investigated triagonist with additional glucagon receptor activation. In research, this manifests in effect size: semaglutide (2.4 mg) achieved 14.9% weight reduction in the STEP-1 study; tirzepatide (15 mg) achieved up to 22.5% in SURMOUNT-1; retatrutide (12 mg) surpassed both with 24.2% in Phase 2 and 28.7% in Phase 3. Half-lives also vary: semaglutide approximately 7 days, tirzepatide approximately 5 days, retatrutide approximately 6 days – all compatible with weekly administration. Regarding liver research, retatrutide offers a unique advantage through the glucagon component: in the MASLD study, liver fat values were reduced by up to 86% (Sanyal et al., 2024), an effect not observed to this extent with pure GLP-1 agonists.
Retatrutide is currently in Phase 3 development by Eli Lilly. The TRIUMPH study program comprises a total of eight Phase 3 trials covering various indications: obesity, type 2 diabetes, MASLD, and knee osteoarthritis. The first completed Phase 3 study (TRIUMPH-4) was published in December 2025; seven more studies are expected to be completed throughout 2026. Market approval is expected no earlier than 2027 or 2028. Until then, retatrutide is exclusively available as a research chemical. Researchers should note that the regulatory framework for research peptides varies by country.
When purchasing retatrutide for research, there are several quality indicators that distinguish reputable suppliers from unreliable ones. First: a current CoA with HPLC data and MS confirmation should be available for each batch. Second: shipping must be temperature-controlled, ideally with cold packs and insulated packaging, as retatrutide is a heat-sensitive peptide. Third: transparent information about origin and manufacturing process is a trust indicator; GMP-compliant production ensures consistent quality. Fourth: suppliers making therapeutic claims or dosage recommendations for human use violate regulatory requirements and should be avoided. Bergdorf Bioscience meets all these criteria: ≥99% purity, individual CoA, GMP production, cold-chain shipping, and exclusively research-oriented communication.
Retatrutide is reconstituted with sterile bacteriostatic water. Inject the water slowly along the inner wall of the vial and gently swirl the vial until the lyophilisate has completely dissolved. Do not shake, as this can damage the peptide structure.
When stored in the refrigerator at 2 to 8 °C and using bacteriostatic water, the reconstituted solution remains stable for up to 28 days. Aliquoting and freezing at −20 °C can further extend shelf life.
Retatrutide is not an approved medication. It is in Phase 3 development (TRIUMPH program, Eli Lilly). As a research chemical, it is legally available for research purposes through specialized suppliers such as Bergdorf Bioscience.
Retatrutide is available in vial sizes of 10 mg, 15 mg, 20 mg, 30 mg, and 50 mg. For longer studies, 2-packs and 3-packs are available at reduced per-unit prices. All variants are shipped with CoA and cold-chain packaging.
In research, combinations with BPC-157 (synergy score 4/5) or TB-500 (score 3/5) are frequently studied. A combination with tirzepatide is contraindicated, as both act on similar receptors. Individual protocols should be developed based on the specific research question.
For research purposes only. Not intended for human consumption.
Scientific editorial: Dr. Sieglinde Klaus