What Is Tirzepatide?
Tirzepatide is a synthetic dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist — the first compound in its class to achieve regulatory approval. With a molecular weight of 4,813.45 Da and the molecular formula C225H348N48O68, tirzepatide is a 39-amino acid linear peptide based on the native GIP sequence with engineered GLP-1R cross-reactivity.
The CAS registry number for tirzepatide is 2023788-19-2. First described by Coskun et al. in 2018 (PMID: 30307095), tirzepatide emerged from Eli Lilly's incretin program with the hypothesis that dual receptor agonism could produce metabolic effects superior to selective GLP-1R agonism alone. The subsequent SURPASS and SURMOUNT clinical trial programs — enrolling over 20,000 subjects — validated this approach with unprecedented efficacy data.
BeaCapra provides research-grade tirzepatide at 99%+ HPLC-verified purity in 5 mg lyophilized format, with batch-specific Certificates of Analysis and the industry's only subscribe & save program.
The Dual Agonist Concept
Tirzepatide represents a paradigm shift in incretin-based research. While GLP-1 receptor agonists like semaglutide act on a single receptor, tirzepatide was engineered to activate both the GIP receptor (GIP-R) and the GLP-1 receptor (GLP-1R) — two distinct incretin pathways that converge on metabolic regulation but operate through complementary mechanisms.
The rationale for dual agonism stems from the observation that GIP and GLP-1 together account for approximately 50-70% of the post-prandial insulin response (the "incretin effect"), with each hormone contributing roughly equally (PMID: 16731544). Selective GLP-1R agonism captures only half of this biology. Tirzepatide's dual mechanism aims to capture both.
GIP Receptor Activity
GIP (glucose-dependent insulinotropic polypeptide) acts primarily on pancreatic β-cells to stimulate insulin secretion and on adipose tissue to regulate lipid metabolism. GIP-R activation enhances insulin sensitivity in adipocytes and may promote more efficient energy storage and utilization (PMID: 33882607). Importantly, GIP-R agonism in the central nervous system appears to complement GLP-1R-mediated appetite suppression through distinct neuronal pathways (PMID: 34293336).
GLP-1 Receptor Activity
Tirzepatide's GLP-1R activity mirrors that of selective agonists: glucose-dependent insulin secretion, glucagon suppression, delayed gastric emptying, and central appetite regulation. However, the relative potency at GLP-1R is lower than at GIP-R — tirzepatide is an imbalanced dual agonist with approximately 5-fold higher potency at GIP-R versus GLP-1R (PMID: 30307095).
Molecular Structure
Tirzepatide's 39-amino acid sequence is based on the native GIP(1-42) peptide with several critical modifications:
- Aib substitution at position 2: α-aminoisobutyric acid replaces native alanine, conferring DPP-4 resistance and extending the circulating half-life (PMID: 30307095).
- GLP-1R cross-reactivity engineering: Specific amino acid substitutions within the C-terminal region introduce GLP-1R binding capability while maintaining GIP-R agonism.
- C20 fatty diacid side chain: A C20 fatty diacid is conjugated via a linker at Lys20, enabling serum albumin binding that extends the half-life to approximately 120 hours (5 days).
- Non-natural amino acid insertions: Additional Aib residues at positions 13 and 14 further enhance proteolytic stability.
Key Published Research
SURPASS Program (Type 2 Diabetes)
The SURPASS trial program evaluated tirzepatide in over 10,000 subjects with type 2 diabetes across eight randomized controlled trials.
SURPASS-1 (PMID: 34170647): Tirzepatide monotherapy (5, 10, or 15 mg weekly) versus placebo in 478 treatment-naive subjects. HbA1c reductions: -1.87% (5 mg), -1.89% (10 mg), -2.07% (15 mg) versus +0.04% placebo at 40 weeks.
SURPASS-2 (PMID: 34170646): Head-to-head versus semaglutide 1 mg weekly (n=1,879). At 40 weeks, tirzepatide 15 mg reduced HbA1c by -2.46% versus -1.86% with semaglutide (p<0.001 for superiority). Body weight reduction: -12.4 kg (tirzepatide 15 mg) versus -6.2 kg (semaglutide 1 mg).
SURPASS-4 (PMID: 34693364): Cardiovascular safety trial in 2,002 subjects with established cardiovascular disease or high risk. Tirzepatide demonstrated non-inferiority to insulin glargine on MACE with superior glycemic and weight outcomes.
SURMOUNT Program (Obesity)
SURMOUNT-1 (PMID: 35658024): The landmark obesity trial enrolled 2,539 subjects with BMI ≥30 (or ≥27 with comorbidity) without diabetes. At 72 weeks, mean weight reductions were: -15.0% (5 mg), -19.5% (10 mg), -20.9% (15 mg) versus -3.1% placebo. The 15 mg dose produced the largest weight reduction ever reported in a phase 3 obesity trial for any pharmacological intervention.
SURMOUNT-2 (PMID: 37385275): Evaluated tirzepatide in 938 subjects with obesity and type 2 diabetes. Weight reductions of -12.8% (10 mg) and -14.7% (15 mg) versus -3.2% placebo at 72 weeks.
SURMOUNT-3 (PMID: 38078870): Tirzepatide following intensive lifestyle intervention. Subjects who lost ≥5% body weight during a 12-week lead-in achieved an additional -18.4% weight loss with tirzepatide 15 mg versus +2.5% with placebo at 72 weeks.
Pharmacokinetic Profile
| Parameter | Value |
|---|---|
| Molecular Weight | 4,813.45 Da |
| Half-Life | ~120 hours (5 days) |
| Bioavailability (SC) | ~80% |
| Time to Peak (Tmax) | 8-72 hours |
| Steady State | 4 weeks |
| Protein Binding | >99% (albumin) |
| Metabolism | Proteolytic cleavage, β-oxidation of fatty acid |
| Primary Elimination | Urine and feces (as metabolites) |
| Receptor Selectivity | ~5x higher GIP-R vs GLP-1R potency |
Semaglutide vs Tirzepatide
The two leading GLP-1-class compounds represent fundamentally different pharmacological approaches. See our detailed head-to-head comparison for a comprehensive analysis. Key differences:
- Receptor selectivity: Semaglutide is a selective GLP-1R agonist; tirzepatide is a dual GIP-R/GLP-1R agonist
- Half-life: Semaglutide ~168 hours; tirzepatide ~120 hours
- Molecular weight: Semaglutide 4,113.58 Da; tirzepatide 4,813.45 Da
- Head-to-head data: SURPASS-2 demonstrated superior glycemic and weight outcomes with tirzepatide 15 mg versus semaglutide 1 mg
Reconstitution and Handling
BeaCapra tirzepatide is supplied as a lyophilized white to off-white powder. For detailed instructions, see our tirzepatide reconstitution guide.
Basic Protocol
- Allow the vial to equilibrate to room temperature (15-25°C) for 10-15 minutes.
- Add the desired volume of bacteriostatic water along the interior glass wall using a sterile syringe.
- Swirl gently in circular motions until the powder fully dissolves (1-3 minutes). Do not shake or vortex.
- Verify the solution is clear, colorless, and free of visible particulates.
- Store reconstituted solution at 2-8°C. Use within 28 days.
Storage Guidelines
| Form | Temperature | Stability |
|---|---|---|
| Lyophilized | -20°C | 24+ months |
| Lyophilized | 2-8°C | 6-12 months |
| Reconstituted | 2-8°C | 28 days |
Purity and Quality
BeaCapra publishes batch-specific Certificates of Analysis for every tirzepatide lot, including reverse-phase HPLC (purity ≥99%), ESI-MS molecular identity confirmation (target: 4,813.45 Da), amino acid analysis, and endotoxin testing (<1 EU/mg). For guidance on interpreting these results, see How to Verify Your Source with COA Analysis.
BeaCapra Tirzepatide
Available in 5 mg lyophilized format at $149.99, or $127.49 with Subscribe & Save (15% off every order). Batch-specific COA included. Same-day shipping on orders before 2PM EST. Free shipping over $149.
Frequently Asked Questions
What makes tirzepatide different from semaglutide?
Tirzepatide is a dual GIP/GLP-1 receptor agonist, while semaglutide selectively targets only the GLP-1 receptor. This dual mechanism activates complementary metabolic pathways. In SURPASS-2, tirzepatide demonstrated superior glycemic and weight outcomes versus semaglutide in a head-to-head comparison.
What is the half-life of tirzepatide?
Approximately 120 hours (5 days), supporting once-weekly research dosing. The extended half-life is conferred by a C20 fatty diacid side chain that enables albumin binding.
How is tirzepatide reconstituted?
With bacteriostatic water, directed against the vial wall. Swirl gently — never shake or vortex. See our complete reconstitution guide.
What purity does BeaCapra's tirzepatide have?
≥99% by HPLC, with mass spectrometry confirmation. Every batch ships with its own Certificate of Analysis.
Can I subscribe for automatic tirzepatide delivery?
Yes. BeaCapra is the only peptide supplier with subscribe & save. Choose delivery every 30, 60, or 90 days and save 15%. Cancel, skip, or modify anytime.
All BeaCapra products are sold for research use only. Not for human consumption.