Tirzepatide

Technical data

INN name

Tirzepatide

Development code

LY3298176

CAS

2023788-19-2

Molecular formula

C225H348N48O68

Molecular weight

4813.45 g/mol

Identity and composition

Tirzepatide (research designation LY3298176) is a synthetic 39-amino-acid peptide designed by Eli Lilly as a dual co-agonist of the GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1) receptors. The molecule is built on a modified backbone of native GIP, into which non-canonical amino acid substitutions (aminoisobutyric acid, Aib) are incorporated at positions 2 and 13 to confer enzymatic resistance against dipeptidyl-peptidase-4 (DPP-4), and a C20 di-acid fatty acid chain conjugated via a γGlu-2xOEG linker at the Lys20 residue.

This acylation allows reversible binding to human serum albumin, which extends the plasma half-life to approximately 5 days in humans, enabling weekly subcutaneous administration in preclinical studies. Structurally, tirzepatide retains the N-terminal domain of GIP necessary for activation of the GIPR receptor and maintains reduced but functional affinity for GLP-1R, generating a dual signaling pattern not observed in monoagonists such as semaglutide or liraglutide.

In the context of preclinical clinical research and animal models, tirzepatide is used exclusively as metabolic study tool to characterize the combined physiology of incretins, energy homeostasis pathways, hepatic and muscular insulin sensitivity, and thermogenesis mechanisms in brown adipose tissue. It is not intended for clinical use outside regulated protocols.

Mechanism of action

The mechanism of action of tirzepatide is complementary dual-incretin, which distinguishes it from single-receptor GLP-1 agonists.

GLP-1R pathway: binding to the Gs protein-coupled receptor activates adenylate cyclase, increases intracellular cAMP in pancreatic β-cells, and enhances glucose-dependent insulin secretion. Additionally, it suppresses pancreatic glucagon secretion under conditions of normoglycemia or hyperglycemia, slows gastric emptying (peripheral satiety effect), and modulates hypothalamic arcuate nuclei (POMC/CART, AgRP/NPY), reducing caloric intake.

GIPR pathway: traditionally considered of lesser therapeutic relevance because of GIP resistance in type 2 diabetes, its coactivation together with GLP-1R seems resensitize the response and to provide direct adipocytic effects: increased regulated postprandial lipid storage, improved adipose blood flow, and modulation of M1/M2 macrophages reducing chronic low-grade inflammation. In the CNS, GIPR activation in the hypothalamus amplifies the anorexigenic signaling of GLP-1R, a phenomenon observed in conditional knockout murine models.

Functional synergy: co-activation produces supra-additive effects on weight loss and glycemic control that exceed the sum of monoagonists at equimolar doses, evidenced in head-to-head SURPASS-2 trials (vs semaglutide 1 mg).

Secondary intracellular cascades: increased PKA, phosphorylation of CREB, expression of UCP1 in BAT (thermogenesis), and activation of mTORC1 in insulin-sensitive tissues contribute to the observed metabolic profile.

Pharmacokinetics

Absorption: after subcutaneous administration, the estimated bioavailability is 80%, with peak plasma concentration (Tmax) reached between 8 and 72 hours (median 24 h) — FDA label.

Distribution: apparent volume of distribution of ~10.3 L; albumin binding >99% mediated by the C20 diacid chain.

Half-life: approximately 5 days (~117 hours) in humans, which allows weekly dosing with steady-state accumulation reached between weeks 4–6.

Metabolism: proteolytic degradation by endopeptidases into its constituent amino acids, without significant involvement of CYP450.

Elimination: clearance ~0.06 L/h; the peptide metabolites are excreted renally and by the reticuloendothelial system.

Linearity: Linear PK in the range of 0.25–15 mg weekly in phase I studies.

Inter-individual variability: CV ~30% for AUC; no adjustment for mild-moderate renal insufficiency in parallel animal models.

Scientific evidence

The available evidence on tirzepatide in research is concentrated in preclinical studies in rodents (DIO mice, ZDF rats, non-human primates) and in human clinical trials in regulated contexts (the SURPASS program for type 2 diabetes, SURMOUNT for obesity).

SURPASS-1 to SURPASS-5 (Lancet, NEJM 2021–2022): HbA1c reductions of up to 2.58% and weight loss of up to 12.9 kg at 52 weeks depending on trial and dose (5, 10, 15 mg/week; SURPASS-1, monotherapy vs. placebo, measured at 40 weeks with smaller magnitudes owing to comparator design). Comparison with semaglutide 1 mg (SURPASS-2): superiority in HbA1c (-2.30% vs -1.86%) and weight (-11.2 kg vs -5.7 kg).

SURMOUNT-1 (NEJM 2022, Jastreboff et al.): in adults with obesity without diabetes, tirzepatide 15 mg weekly induced a mean weight loss of 22.5% at 72 weeks (vs 2.4% placebo), a magnitude comparable to restrictive bariatric surgery.

SURMOUNT-2 (Lancet 2023): in T2D + obesity, weight reduction of 15.7% at 72 weeks.

Key preclinical studies: Coskun et al. 2018 (Mol Metab) characterized the dual-receptor pharmacology; Frias et al. demonstrated metabolic superiority vs dulaglutide in diabetic models.

Mechanistic findings in animal research: increase in UCP1 in BAT, reduction of hepatic steatosis (NASH), improvement in insulin sensitivity measured by euglycemic-hyperinsulinemic clamp.

There are no published trials of tirzepatide in human sports science or in cosmetic indications; any use outside of diabetes/obesity remains strictly investigational.

Research applications

The documented applications in research include:

• Type 2 diabetes: main development protocol. db/db murine models and ZDF rats show normalization of fasting and postprandial glycemia at doses of 3–10 nmol/kg/week.

• Obesity and weight reduction: DIO mice (high-fat diet) reach weight reductions of 20–25% at 4 weeks with allometrically scaled human-equivalent doses. The mechanism combines suppression of intake, an increase in BAT thermogenesis and a selective reduction of visceral adiposity.

• Non-alcoholic steatohepatitis (NASH/MASH): a phase II trial in humans (SYNERGY-NASH, Loomba et al., NEJM 2024) shows histological resolution without worsening of fibrosis in 51.8% (5 mg), 62.8% (10 mg), and 73.3% (15 mg) of patients at 52 weeks, vs 13.2% with placebo.

• Obstructive sleep apnea: SURMOUNT-OSA (2024) reported reductions in the apnea-hypopnea index correlated with weight loss.

• Cardiovascular research: The ongoing SURPASS-CVOT evaluates major cardiovascular events; preliminary data suggest a reduction in systolic blood pressure of 5–10 mmHg, improvement in lipid profile (triglycerides -25%, LDL -8%) and reduction in inflammatory markers (hs-CRP).

• Models of diabetic chronic kidney disease: reduction of albuminuria and preservation of estimated GFR in animal studies.

Any application in in vivo research must be carried out under a protocol approved by an animal bioethics committee or the corresponding human IRB.

Research protocols

The protocols described in preclinical literature and clinical trials follow a scheme of mandatory upward titration to mitigate gastrointestinal effects:

Standard human regimen (reference):

• Weeks 1–4: 2.5 mg/week (initiation dose, not therapeutic)
• Weeks 5–8: 5 mg/week
• Weeks 9–12: 7.5 mg/week
• Weeks 13–16: 10 mg/week
• Weeks 17–20: 12.5 mg/week
• Week 21 onward: 15 mg/week (maximum dose)

Route: strictly subcutaneous, rotating sites (abdomen, thigh, deltoid) to avoid lipodystrophy.

Frequency: once a week, same day, independent of meals.

Typical duration of a research protocol: 24–72 weeks to assess metabolic and weight-related outcomes.

Animal models: human equivalent doses are scaled by body surface area (factor 12.3 for mouse, 6.2 for rat). Equivalent frequency: every 3–4 days in rodents due to PK differences.

Research combinations: with an SGLT2i (empagliflozin) in NASH/MASH models; with exercise resistance in body composition studies.

Monitoring: blood glucose, quarterly HbA1c, pancreatic function (amylase/lipase), renal function, lipid profile, weight and body composition by DXA.

Reconstitution

Lyophilized tirzepatide is reconstituted with bacteriostatic water (BAC) as the preferred solvent for its multi-dose preservation capability.

Standard procedure:

1. Equilibrate vial and solvent to room temperature (15–30 min out of the refrigerator).
2. Clean the stopper with 70% isopropanol.
3. Inyectar el volumen de BAC seleccionado laterally onto the wall of the vial (never directly onto the powder).
4. Do not shake: gently roll between the palms for 30–60 seconds until complete dissolution.
5. Inspeccionar visualmente: solución debe ser transparente, incolora, sin partículas.

Reference concentrations (vial 10 mg):

• 1 mL BAC → 10 mg/mL (1 mg = 0.1 mL = 10 IU in a U-100 insulin syringe)
• 2 mL BAC → 5 mg/mL (1 mg = 0.2 mL = 20 IU)
• 3 mL BAC → 3.33 mg/mL (1 mg = 0.3 mL = 30 IU)

Recommended syringe: U-100 insulin 0.3–1 mL, 29–31G × 8–13 mm needle.

Dose calculation: volume (mL) = dose (mg) / concentration (mg/mL).

For higher-milligram presentations (30, 40, 50 mg) adjust the BAC volume proportionally to maintain a manageable concentration. It is recommended not to exceed 20 mg/mL to avoid viscosity.

Stability and storage

Lyophilized vial (sealed):

• Storage: 2–8 °C under refrigeration.
• Stability: up to 24 months per the manufacturer, protected from light.
• Room-temperature tolerance: up to 30 days without significant loss of documented activity in forced-degradation studies.

Vial reconstituted with BAC:

• Storage: strict 2–8 °C.
• Post-reconstitution stability: 28 days preserving potency >95%.
• Do not freeze after reconstitution (microcrystal formation can compromise integrity).
• Protect from direct light (wrapping in aluminum foil or an opaque box recommended).

Indicators of visual degradation:

• Turbidity, opalescence, precipitate: discard.
• Color change (yellow, brown): discard.
• Particles in suspension: discard.

Transport:

• Short shipments (<72 h) can be made with a cold gel pack; lyophilized vials tolerate temperatures up to 25 °C transiently.
• Avoid repeated freeze-thaw cycles.

Storage of reconstituted material for prolonged use: aliquots in individual sterile vials can be frozen a single time at -20 °C, extending viability ~90 days in parallel studies with other GLP-1 analogs.

Safety profile

The safety profile of tirzepatide in human clinical research documents the following events:

Gastrointestinal events (most frequent, dose-dependent):

• Nausea: 12–22% (predominant during titration)
• Diarrhea: 12–17%
• Vomiting: 5–10%
• Constipation: 6–11%
• Dyspepsia, bloating: 5–8%

Most are mild-to-moderate and transient (resolution in 2–4 weeks).

Pancreatitis: incidence <0.5% in pivotal trials; a definitive causal association has not been demonstrated, but monitoring of amylase/lipase is standard.

Hypoglycemia: rare in monotherapy (<2%); increases significantly in combination with sulfonylureas or insulin.

Thyroid (rodent): in 2-year carcinogenicity studies in rats, thyroid C-cell hyperplasia was observed. Contraindicated in humans with a personal/family history of medullary thyroid carcinoma or MEN-2.

Injection site reactions: 3–5%, mild.

Hypersensitivity reactions: <1%, manageable.

Changes in heart rate: mean increase of 2–4 bpm (GLP-1R effect).

Renal function: dehydration from severe vomiting can precipitate pre-renal AKI (isolated reports).

Pregnancy: contraindicated; animal studies show effects on fetal development.

In animal research, supra-pharmacological doses are associated with severe weight loss, prolonged hypophagia and, in chronic studies, thyroid hyperplasia.

Comparative context

vs Semaglutide (pure GLP-1R agonist):

• HbA1c efficacy: tirzepatide 15 mg surpasses semaglutide 1 mg by ~0.5% (SURPASS-2).
• Weight efficacy: tirzepatide 15 mg ~22.5% vs semaglutide 2.4 mg ~15% (cross-trial estimate).
• Mechanism: tirzepatide adds a GIPR component; semaglutide is a monoagonist.
• Frequency: both weekly.

vs Liraglutide: tirzepatide clearly superior in glycemia and weight; liraglutide requires daily dosing.

vs Retatrutide (triple GLP-1/GIP/GCG agonist, investigational): retatrutide adds a glucagon component, with preliminary phase II data suggesting weight loss of up to 24% at 48 weeks, but with a more intense GI profile. Tirzepatide has greater clinical maturity.

vs Dulaglutide: tirzepatide superior in all comparative metabolic outcomes (SURPASS-5).

vs CagriSema (cagrilintide + semaglutide): cross-trial comparison suggests similar weight efficacy (~22%), but with a combined dose vs a single molecule.

vs Bariatric surgery: tirzepatide 15 mg approaches sleeve gastrectomy (~25% loss), but less than Roux-en-Y gastric bypass (~30–35%) and reversible upon discontinuation.

Tolerability profile: GI effects milder than retatrutide, similar to semaglutide at high doses.

Investigational cost-effectiveness: higher molar dose required than semaglutide, but with compensatory magnitude of effect.

History and development

Tirzepatide was developed by Eli Lilly and Company under the research code LY3298176, initially published by Coskun et al. in Molecular Metabolism (2018) after a discovery program that explored >1,000 GIP/GLP-1 analogs.

Chronological milestones:

• 2018: Preclinical pharmacological characterization published.
• 2019: Start of the SURPASS program (phase III diabetes).
• 2020: Start of SURMOUNT (phase III obesity).
• May 2022: FDA approval for type 2 diabetes.
• September 2022: EMA approval.
• November 2023: FDA approval for obesity.
• 2024: Additional approval for obstructive sleep apnea associated with obesity.

Scientific innovation: the first molecule of its class to demonstrate the clinical viability of GIPR/GLP-1R co-agonism, refuting the previous dogma about GIP obesogenicity in humans. Its success has catalyzed the development of tri-agonists (retatrutide) and combinations with amylin (CagriSema).

Regulatory context: classified as a prescription drug in the USA, Europe, the United Kingdom, Canada, Japan, Mexico (via COFEPRIS), and other markets. Its use in animal research is subject to local animal-welfare regulations (NOM-062 in Mexico).

Patents: composition of matter (US 10,544,200) in force until ~2036.

FAQ

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Certificate of analysis per batch

Tirzepatide batches with certificate of analysis published in the COA catalog:

• Lot EXO010626033A — 100 mg, issued 2026-05-23
• Lot EXO010626033B — 30 mg, issued 2026-05-21
• Lot EXO010626033C — 40 mg, issued 2026-05-25
• Lot EXO010626033D — 60 mg, issued 2026-05-23
• Lot EXO010626033E — 20 mg, issued 2026-05-23
• Lot EXO010626033F — 10 mg, issued 2026-05-28
• Lot EXO010626033G — 50 mg, issued 2026-05-20
• Lot EXO010626033H — 5 mg, issued 2026-05-23
• Lot EXO010626033J — 15 mg, issued 2026-05-22

Scientific references (8)

Peer-reviewed literature on Tirzepatide, with its PubMed identifier where available:

• Tirzepatide versus Semaglutide for Weight Management (Frias JP, et al. · New England Journal of Medicine · 2025) — Head-to-head comparison showing superiority of tirzepatide over semaglutide for weight loss. PMID 40353578.
• SYNERGY-NASH: Tirzepatide in MASH with fibrosis (Loomba R, Hartman ML, Lawitz EJ, et al. · New England Journal of Medicine · 2024) — 52-week phase 2 study in 190 patients with biopsy-confirmed MASH F2/F3, evaluating tirzepatide vs placebo. PMID 38856224.
• Tirzepatide Once Weekly for the Treatment of Obesity (Jastreboff AM, et al. · New England Journal of Medicine · 2022) — Phase 3 SURMOUNT-1 clinical trial with 2,539 participants showing significant weight loss. PMID 35658024.
• SURPASS-2: Tirzepatide vs Semaglutide 1 mg weekly in T2DM (Frías JP, Davies MJ, Rosenstock J, et al. · New England Journal of Medicine · 2021) — 40-week phase 3 head-to-head trial in 1,879 patients with T2DM inadequately controlled with metformin, comparing tirzepatide 5/10/15 mg vs semaglutide 1 mg weekly. PMID 34170647.
• Discovery and molecular characterization of tirzepatide (Coskun T, Sloop KW, Loghin C, et al. · Molecular Metabolism · 2018) — Preclinical characterization of the first dual GIP/GLP-1 agonist, including receptor affinity, pharmacokinetics, and efficacy in rodent and non-human primate models. PMID 30473097.
• Efficacy and safety of a novel dual GIP and GLP-1 receptor agonist tirzepatide in patients with type 2 diabetes (SURPASS-1): a double-blind, randomised, phase 3 trial (Rosenstock, et al. · The Lancet · 2021) PMID 34186022.
• Dual GIP and GLP-1 Receptor Agonist Tirzepatide Improves Beta-cell Function and Insulin Sensitivity in Type 2 Diabetes (Thomas, et al. · Journal of Clinical Endocrinology & Metabolism · 2021) PMID 33236115.
• Tirzepatide, a dual GIP/GLP-1 receptor co-agonist for the treatment of type 2 diabetes with unmatched effectiveness regrading glycaemic control and body weight reduction (Nauck, D'Alessio · Cardiovascular Diabetology · 2022) PMID 36050763.

Guides and articles about Tirzepatide

Lecturas del blog de EXOMA que la editorial asoció a este compuesto:

• Semaglutide vs. Tirzepatide vs. Retatrutide: Triple GLP-1 Comparison
• Retatrutide vs. Tirzepatide: Scientific Comparison for Research
• Tirzepatida in Mexico: guía completa for research (2026)

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