Retatrutide 5mg 99% pure — triple GLP-1/GIP/GCGR agonist discovery format

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What the parcel contains

One sealed vial of Retatrutide 5mg, lyophilised, without individual labelling.

What you also need

Bacteriostatic water for reconstitution and 1 ml precision syringes graduated in 100 units, sold separately. The vial alone cannot be used as is.

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Retatrutide 5mg is the discovery format for researchers approaching the GLP-1/GIP/GCGR triple agonist. It is sized for the initial titration phase and early exploratory plateaus, with maximum safety margin in case of early protocol discontinuation. One vial typically covers 2-4 weeks depending on dose, allowing individual tolerance validation before larger volumetric commitment.

Operational use: at initial plateau 2mg/week (Jastreboff 2023 protocol), a 5mg vial delivers 2 full doses, meaning 2 weeks of W1-2 titration. At 4mg/week (W5-8 plateau), one vial covers 1 week. At 5mg single dose, the vial is consumed in one injection. This fine granularity lets novice researchers familiarize with the molecule, calibrate early metabolic markers (fasting glucose, ALT, heart rate), and decide knowingly whether to commit to a long cycle with a more economical format (10/20/30/40mg).

Reconstituted at 1 mL bacteriostatic water, it delivers 5 mg/mL; at 0.5 mL, 10 mg/mL. For researchers preferring a standardized 5 mg/mL concentration across the retatrutide range, reconstituting all vials (5/10/15/20/30/40mg) with proportional volumes (1/2/3/4/6/8 mL) facilitates protocol standardization. The 5mg format is also useful for gradual tapering phases after a long cycle: descending from 12mg to 8mg/4mg/2mg/0 over a few weeks, using a 5mg for the last doses.

Science

01
Mechanism of action

Retatrutide is the first triple incretin-mimetic agonist to reach phase II/III clinical development. Its sequence combines three activities: GLP-1R, GIPR, and GCGR (glucagon receptor), a design that unites in a single molecule the three main metabolic levers of energy regulation. Coskun and Urva (2022, pharmacological description) describe the engineering: modified sequence derived from native GIP, Aib2 and Aib13 substitutions resisting DPP-4, and a C20 diacid fatty-acyl chain grafted to a lysine via a gamma-glutamate linker to extend half-life to approximately 6 days. The affinity profile is calibrated for triple balance: full agonist at GIPR, full agonist at GLP-1R, partial agonist at GCGR, preserving glycemia while exploiting glucagon thermogenic benefits.

The GCGR arm is retatrutide's signature. Hepatic glucagon increases gluconeogenesis and lipolysis via PKA/CREB activation, stimulates brown adipose tissue thermogenesis, and reduces hepatic triglyceride accumulation. This activity partly antagonizes the GIP lipogenic effect and translates clinically into weight loss exceeding tirzepatide's. Tuning the GCGR / GLP-1 + GIP affinity ratio is critical: too much GCGR would trigger hyperglycemia; too little would cancel the thermogenic benefit. Retatrutide was optimized to maximize brown adipose activity without net glycemic disturbance, thanks to the combined glucose-normalizing effect of the GLP-1/GIP incretins.

Additive mechanisms: central activation of GLP-1R / GIPR hypothalamic satiety circuits, slowed gastric emptying, amplified glucose-dependent insulin secretion, direct adipocyte lipolysis via GCGR, brown thermogenesis via UCP1, and increased hepatic lipid oxidation. Obese mouse models (Coskun 2022) show basal energy expenditure +8-12% vs vehicle, a major contributor to the magnitude of weight loss observed in phase II clinical trials.

Pharmacokinetics: approximate terminal half-life 6 days, Cmax at 40-48 hours post-injection, steady-state in 4-5 weeks. Proteolytic clearance (no CYP450), no major pharmacokinetic interactions expected. Subcutaneous bioavailability is nearly complete thanks to albumin binding conferred by the C20 chain. Weekly administration standardizes pharmacokinetics, simplifies protocols, and smooths plasma concentrations — conditions favorable for reproducible cohort studies.

In exploratory research, retatrutide represents the most ambitious incretin agent currently available. Its signaling complexity (triple agonism) imposes heightened methodological vigilance: systematic glycemic monitoring to detect any paradoxical hyperglycemia linked to the glucagon arm, regular hepatic panel given the lipolytic effect, and lean mass tracking to quantify the share of weight loss linked to muscle depletion under severe caloric restriction.

Clinical data

02Clinical studies

Clinical data on retatrutide are still recent but spectacular. The pivotal phase II obesity trial Jastreboff 2023 NEJM (Retatrutide Phase 2 Obesity Trial) tested 1/4/8/12mg weekly in 338 obese non-diabetic adults over 48 weeks. Mean weight loss: -8.7% (1mg), -17.1% (4mg), -22.8% (8mg), -24.2% (12mg) vs -2.1% placebo. At 12mg, 92% of participants lost >= 5%, 75% >= 15%, 56% >= 20%, and 26% lost >= 25%. These figures are the highest ever published for an anti-obesity pharmacological agent and directly rival sleeve gastrectomy bariatric surgery (typically -25% at 1 year).

Phase II diabetes study Rosenstock 2023 Lancet: 281 T2D patients over 36 weeks with doses 0.5/4/8/12mg. HbA1c: -2.02% at 12mg vs -0.01% placebo; weight loss -16.94% vs -3.0% placebo at 12mg. Retatrutide demonstrated an effect equivalent or superior to the best GLP-1 mono-agonists on diabetes while producing markedly stronger weight loss.

Phase II hepatic steatosis study Sanyal 2024 Lancet: retatrutide 5-10mg weekly in 98 patients with MASLD and obesity, over 48 weeks. Hepatic fat fraction reduction: -57.0% (5mg), -81.4% (10mg) vs -0.3% placebo. At 10mg, 85% of patients reached hepatic fat fraction < 5% (resolution threshold), 74% had >= 30% reduction. These results exceed those of any other pharmacological agent tested on MASLD, including tirzepatide in SYNERGY-NASH.

Phase III TRIUMPH trials are ongoing. TRIUMPH-1 (adult obesity, n=2250), TRIUMPH-2 (obesity with comorbidities), TRIUMPH-3 (type 2 diabetes + obesity), TRIUMPH-4 (MASH with fibrosis), TRIUMPH-6 (sleep/OSA): results expected 2025-2027. The program was designed to demonstrate broad superiority vs tirzepatide (direct comparator in certain arms) on weight loss, metabolic improvement, hepatic steatosis, and sleep apnea.

Tolerance profile: in phase II trials, gastrointestinal adverse events (nausea, vomiting, diarrhea, constipation) are frequent but mostly mild-to-moderate and concentrated in the early titration weeks. Adverse-event discontinuation rate was 6-16% depending on dose. Two signals deserve vigilance: mean heart rate increase of 3-7 bpm (similar to tirzepatide, likely linked to the GLP-1 arm), and modest ALT elevation in some patients (likely linked to GCGR-induced hepatic lipolysis). Retatrutide did not produce significant hypoglycemia in non-diabetics, confirming that the glucagon arm is properly balanced by the incretin arm.

In research these references structure protocols. The standard phase II titration was: 2mg W1-4, 4mg W5-8, 8mg W9-12, 12mg W13+ (progression by 4mg steps every 4 weeks). Researchers seeking to reproduce Jastreboff 2023 conditions use this schema as reference. Phase III trials test extended plateaus up to 16mg in certain arms, reflecting the possibility of an unsaturated dose-response even at 12mg.

1
ObésitéTriple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial
Jastreboff AM, Kaplan LM, Frías JP, et al. · New England Journal of Medicine · 2023
2
Diabète type 2Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a phase 2 trial
Rosenstock J, Frías J, Jastreboff AM, et al. · The Lancet · 2023

The listed studies are provided for documentation and research purposes only. They do not constitute a therapeutic indication nor a recommendation for human use. This product is strictly for laboratory use only (RUO).

Lab workflow

03
Research protocols

Jastreboff 2023 NEJM initial titration phase protocol. W1-4 plateau: 2mg weekly.

Option A — initial titration 2mg/week (2 weeks per vial): reconstitute 5mg with 1 mL bacteriostatic water (concentration 5 mg/mL). Draw 0.4 mL (40 units on U100 syringe) delivers 2mg. One vial = 2 weekly doses = 2 weeks of W1-2 titration. Chain with a 2nd 5mg vial for W3-4.

Option B — intermediate plateau 4mg/week (1 week per vial): reconstitute 5mg with 1 mL (5 mg/mL). Draw 0.8 mL (80 units) delivers 4mg. One vial = 1 weekly dose + 1mg residual to discard.

Option C — 5mg monodose (1 week per vial): reconstitute 5mg with 1 mL (5 mg/mL). Draw 1 mL (100 units) delivers 5mg. One vial = 1 single dose. Useful as intermediate dose outside strict Jastreboff protocol, for custom research designs.

Option D — post-cycle taper (2-3 weeks per vial): after a long cycle at 12mg, descend progressively over 4-6 weeks to avoid hormonal rebound and weight yo-yo. Typical schedule: post-stop W1 8mg, W2 6mg, W3 4mg, W4 2mg, W5 0. A 5mg vial reconstituted with 1 mL covers doses 4mg (draw 0.8 mL) and 2mg (draw 0.4 mL), meaning 2 weeks of taper.

Injection site: rotate 4 abdominal quadrants, minimum 2.5 cm from navel. Angle 45-90 degrees depending on skinfold. Inject slowly (5-10 seconds), hold 10 seconds before withdrawal. Inspect site before injection to avoid zones with preexisting lipohypertrophy.

Initial-phase monitoring: daily journal of adverse events (nausea, satiety, fatigue, bowel movements) during the first 4 weeks. Weekly weigh-in at fixed time. Fasting glucose every 15 days during titration. HbA1c at W0 before first injection as baseline.

Reconstitution for this format (5 mg)Standard volumes used in laboratory settings

Water added	Concentration	Reading marker
1 ml	5 mg/ml	40 UI = 2 mg
2 ml	2,5 mg/ml	40 UI = 1 mg

The volume of water does not change the product, only its concentration. Introduce the water slowly along the vial wall, never directly onto the lyophilisate, then swirl without shaking. Markers given on a 1 ml syringe graduated in 100 units.

Asepsis

Disinfect surfaces and stoppers (70% alcohol).

Solvent

Draw the required volume of bacteriostatic water.

Introduction

Inject gently against the vial wall (avoid direct jet on powder).

Solubilization

Roll the vial gently. Do not shake vigorously (degradation risk).

Solution storageOnce reconstituted: 2-8°C (refrigerator).

WarningTheoretical tool for chemical handling. Does not constitute medical advice.

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What is normal on arrivalThe observations that worry customers, and are not defects

The amount of powder looks tiny. A lyophilisate takes up a few millimetres at the bottom of the vial, sometimes just a translucent film. The stated weight is there.
The powder is compact, stuck to the wall or to the stopper. Transport moves the freeze-dried cake around. It changes nothing to reconstitution.
The vial carries no individual label. That is our standard packaging, not a downgraded vial.
After reconstitution, deposits or filaments appear. This is common, especially with small molecules. Let it settle and roll the vial between your palms, never shake it.
The parcel is plain. Nothing on the outside indicates the contents or the brand name.

What is not normal: a cracked vial, an uncrimped cap or a stopper that moves, powder that has liquefied or changed colour. In those specific cases, write to us with a photo and we take the vial back.

Handling

04Storage & handling

Lyophilized retatrutide stores up to 24 months between 2 and 8 degC, protected from light, in its original borosilicate vial sealed under inert atmosphere. The peptide is stable in solid form; degradation pathways become operational only after solubilization. Extended stocks can tolerate -20 degC (deep freeze) without documented integrity loss, provided freeze-thaw cycles are avoided as they introduce mechanical stress on tertiary structure.

After reconstitution with bacteriostatic water (0.9% benzyl alcohol), the solution stores for 21-28 days at 2-8 degC, protected from light. The C20 diacid chain is more hydrophobic than semaglutide's (C18) and tirzepatide's, slightly slowing degradation but increasing oligomerization propensity if the solution undergoes agitation or shear. Dominant degradation pathways: methionine oxidation (specifically Met30), asparagine deamidation (Asn25, Asn35) pH-sensitive, aspartate isomerization, and oligomerization/fibrillation via the C20 lipid anchor. After 28 refrigerated days, typically expect 5-10% activity loss, acceptable for most research protocols.

Operational recommendations: (1) handle the reconstituted vial with powder-free nitrile gloves to avoid surface contaminants that would catalyze degradation; (2) never vortex or shake, prefer gentle rotation with the vial tilted at 45 degrees until complete dissolution (typically 30-60 seconds); (3) if a precipitate persists after 5 minutes, warm gently to 25 degC (hand, never > 30 degC); (4) post-reconstitution storage must be a constant 2-8 degC, ideally low in the fridge (thermally most stable area), in a peptide-dedicated compartment (no contact with food or other volatile products).

For long-duration research cycles, choosing the right format is the first line of defense against degradation. A 12-week cycle at 12mg/week requires 144mg. In 5mg format that means 29 reconstitutions; in 10mg, 15; in 20mg, 8; in 30mg, 5; in 40mg, 4 reconstitutions. Each reconstitution reduction divides by the same factor the contamination risk, operator time, and consumable costs (bacteriostatic water, sterile syringes, needles, wipes). Golden rule: choose the format whose quantity divided by the weekly dose yields between 2 and 4 weeks of coverage.

01Why is retatrutide called a "triple agonist" and what does it change in practice?

Retatrutide simultaneously activates three receptors: GLP-1R, GIPR, and GCGR (glucagon). Mono-agonists (semaglutide) activate only GLP-1R; dual agonists (tirzepatide) add GIPR. Retatrutide pushes the architecture one step further with the glucagon arm, adding brown adipose tissue thermogenesis, direct hepatic lipolysis, and massive intrahepatic triglyceride reduction. Clinical consequence (Jastreboff 2023 NEJM): mean weight loss -24.2% at 12mg/48w, vs -20.9% for tirzepatide (SURMOUNT-1). The GCGR agonism is calibrated as partial to avoid triggering hyperglycemia, balanced by the GLP-1/GIP glucose-normalizing effect.

02What volume of bacteriostatic water should be used to reconstitute a retatrutide vial?

Volume depends on format and target weekly dose. For 5mg, 1 mL = 5 mg/mL (5mg dose in 1 mL). For 10mg, 2 mL = 5 mg/mL, or 1 mL = 10 mg/mL. For 15mg, 3 mL = 5 mg/mL, or 1.5 mL = 10 mg/mL. For 20mg, 4 mL = 5 mg/mL, or 2 mL = 10 mg/mL. For 30mg, 3 mL = 10 mg/mL (10mg dose in 1 mL), or 6 mL = 5 mg/mL. For 40mg, 4 mL = 10 mg/mL. Practical rule: pick a concentration yielding 100 units (1 mL) on a U100 syringe for the target dose, maximizing measurement precision.

03How long can reconstituted retatrutide be stored, and what signs indicate degradation?

21-28 days at 2-8 degC protected from light. The benzyl alcohol in bacteriostatic water preserves microbial sterility but not chemical integrity. Degradation pathways: Met30 oxidation, Asn25/35 deamidation, oligomerization via C20 diacid chain (more hydrophobic than semaglutide's C18, therefore more prone to protein interactions). Visual signs: cloudiness, precipitate, crystals, yellow or amber color, flocculation on gentle swirl. A healthy solution is clear and colorless. If in doubt, discard and reconstitute. Expected activity loss 5-10% after 28 days. For long cycles, plan reconstitutions to minimize time since reconstitution.

04Why must retatrutide be titrated progressively, and according to what schedule?

Titration is imposed by gastrointestinal tolerance, aggravated by the glucagon arm's additional effect on motility and glycemia. At full dose from start, 60-80% of subjects experience severe nausea, vomiting, and fatigue; early discontinuation climbs >20%. The Jastreboff 2023 NEJM protocol requires: 2mg weekly W1-4, 4mg W5-8, 8mg W9-12, 12mg W13+ (4mg steps every 4 weeks). For exploratory protocols targeting > 12mg, extend titration: 16mg W17-20, 20mg W21+ (4mg steps). For ultra-high doses (30-40mg), extend further with 5mg steps. Titration preserves adherence and allows gastrointestinal receptor desensitization.

05What are key drug interactions and contraindications for retatrutide?

Absolute contraindications: personal or family history of medullary thyroid carcinoma or MEN2 syndrome (preclinical rodent signal on C-cells, precautionary principle), active pancreatitis, severe hepatic insufficiency (the glucagon arm increases hepatic lipolysis and may worsen compromised function). Interactions: slowed gastric emptying alters absorption of narrow-therapeutic-window oral drugs (warfarin, digoxin, levothyroxine, immunosuppressants). Oral contraceptives: efficacy potentially reduced for 4 weeks after each dose increment, supplementary barrier contraception recommended. Increased vigilance on insulin and sulfonylureas (potentiated hypoglycemia despite glucagon balance).

06Can retatrutide be combined with other research peptides (BPC-157, TB-500, CJC-1295, ipamorelin)?

Combinations are explored in advanced research contexts. BPC-157 and TB-500 (healing and tissue repair) are pharmacodynamically orthogonal to retatrutide, no interaction expected. CJC-1295 + ipamorelin (GH/IGF-1 stimulation) can potentiate certain metabolic effects and require enhanced glycemic monitoring, especially given the retatrutide glucagon arm which may add to the gluconeogenic effect of the GH axis. No direct pharmacokinetic interaction expected (retatrutide proteolytic clearance, no CYP450). In exploratory research, documenting each combination and observed effects is essential to exploit data value.

07Which format should I choose for a long cohort protocol (16+ weeks) at 12mg/week?

For 16 weeks at 12mg/week, total need 192mg. Options: 20mg format yields 10 reconstitutions (1.67 weeks coverage per vial, tight stability margin); 30mg format yields 7 reconstitutions (2.5 weeks per vial, comfortable margin); 40mg format yields 5 reconstitutions (3.3 weeks per vial, very comfortable margin). For 24 weeks at 12mg/w, need 288mg: 40mg format = 8 reconstitutions (optimal margin). 30mg and 40mg are the formats of choice for long cycles. 5mg and 10mg target initial titration (before reaching the 12mg plateau), and 15mg/20mg for intermediate 4-8 week cycles.

08Why should retatrutide never be mixed with insulin or another peptide in the same syringe?

Retatrutide formulations include a phosphate/citrate buffer and excipients (phenol, methionine antioxidant) calibrated for its stability. Mixing with insulin (pH varying by type) causes precipitation, C20 chain oligomerization, and activity loss. Mixing with another peptide (BPC-157, TB-500, CJC-1295) triggers hydrophobic interactions between acylated chains (C20 vs other esters) and cross-degradation. In research, always administer as separate injections: different sites, fresh syringes, minutes apart to isolate kinetics and cleanly document each agent's effects. This discipline is particularly critical for retatrutide whose triple agonism already complicates experimental analysis.

Benchmark

Similar peptides

Versus tirzepatide (GLP-1/GIP dual agonist): retatrutide surpasses tirzepatide in documented weight efficacy. Phase II Jastreboff 2023 NEJM: -24.2% at 12mg/48w for retatrutide vs SURMOUNT-1 Jastreboff 2022: -20.9% at 15mg/72w for tirzepatide. The absolute 3.3-point weight gap over a shorter window (48 vs 72 weeks) suggests retatrutide reaches maximum plateau faster and further. The GCGR arm adds hepatic thermogenesis and lipolysis that tirzepatide does not generate. Limit: retatrutide is newer, with fewer long-term data (phase III ongoing, not yet published), and the glucagon arm imposes stricter ALT/AST follow-up.

Versus semaglutide (GLP-1 mono-agonist): considerable gap. STEP-1 Wilding 2021 NEJM: -14.9% at 2.4mg/68w for semaglutide vs -24.2% at 12mg/48w for retatrutide. For a researcher seeking maximal metabolic performance, retatrutide is superior by >9 weight points over a shorter window. Semaglutide remains the option when gastrointestinal tolerance is problematic (milder profile) or on tight budget (older molecule, available in more economical formats).

Versus liraglutide 3mg (Saxenda): massive gap (-8% over 56 weeks Pi-Sunyer 2015 NEJM SCALE vs -24.2% over 48 weeks for retatrutide). Liraglutide is outpaced by all modern incretin agents and holds residual interest only for its long-term data (> 5 years) which retatrutide still lacks.

Versus bariatric surgery (sleeve, Roux-en-Y bypass): the most strategically interesting comparison. Sleeve typically produces -25% at 1 year, bypass -30-35%. Retatrutide 12mg produced -24.2% at 48 weeks (phase II) and could reach -28-30% at 72 weeks by extrapolation (TRIUMPH phase III results pending). For the first time, a non-invasive pharmacological agent approaches or exceeds the least aggressive bariatric surgery. Limit: weight regain is faster upon drug discontinuation than after surgery, and cumulative chronic treatment cost may equal or exceed surgery at 5-7 years.

Versus other triple/multi-agonists in development: survodutide (GLP-1/GCGR Boehringer Ingelheim), mazdutide (GLP-1/GCGR Eli Lilly), orforglipron (oral non-peptide GLP-1 Eli Lilly), HRS9531 (GLP-1/GIP Hengrui): each represents a distinct signaling architecture. Retatrutide remains the most advanced triple agonist in phase III and holds the highest published weight efficacy to date.

Versus bupropion-naltrexone, orlistat, phentermine-topiramate: the gap is such that these agents no longer compete. They remain relevant as inexpensive oral alternatives for patients refusing injection or with incretin contraindications.

Research positioning: retatrutide is the most powerful tool currently available to study multi-receptor metabolic regulation. Its triple agonism allows simultaneous study of combined GLP-1 + GIP + glucagon effects, experimental dissections impossible with mono-agonists or dual agonists. Exploratory protocols thus gain unique signaling benefit at the cost of more demanding monitoring complexity.

Full guide: Retatrutide — mechanism, studies, dose comparison

Retatrutide 5mg Weight Loss

Metabolism

01
Mechanism of action

02Clinical studies

03
Research protocols

Asepsis

Solvent

Introduction

Solubilization

04Storage & handling

Similar peptides

Metabolism

Asepsis

Solvent

Introduction

Solubilization

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