Tirzepatide
Also known as: Mounjaro, Zepbound, LY3298176
Tirzepatide is a first-in-class dual GIP/GLP-1 receptor agonist developed by Eli Lilly. FDA-approved as Mounjaro for type 2 diabetes and Zepbound for chronic weight management, it has demonstrated unusual weight loss of up to 22.5% in clinical trials.
Tirzepatide is a 4,813.45 Da research peptide. Tirzepatide is a first-in-class dual GIP/GLP-1 receptor agonist developed by Eli Lilly. FDA-approved as Mounjaro for type 2 diabetes and Zepbound for chronic weight management, it has demonstrated unusual weight loss of up to 22.5% in clinical trials.
Also called: Mounjaro, Zepbound, LY3298176
4,813.45
Molecular Weight
Daltons
3
Strong Evidence
benefits
5
Studies Cited
peer-reviewed
2500-2500
Typical Dose
mcg
Overview
Tirzepatide is a novel synthetic peptide that functions as a dual agonist of both the glucose-dependent insulinotropic polypeptide (GIP) receptor and the glucagon-like peptide-1 (GLP-1) receptor. Developed by Eli Lilly and Company, it represents the first molecule in a new pharmacological class; dual incretin agonists. Tirzepatide received FDA approval in May 2022 as Mounjaro for the treatment of type 2 diabetes mellitus, and in November 2023 as Zepbound for chronic weight management in adults with obesity or overweight with at least one weight-related comorbidity. The SURPASS and SURMOUNT clinical trial programs demonstrated notable efficacy, with participants achieving up to 22.5% body weight reduction, surpassing all existing approved weight-loss medications. Tirzepatide's dual mechanism is thought to provide additive or complementary metabolic benefits beyond what GLP-1-only agonists achieve, including superior glycemic control, greater weight loss, and improved cardiovascular risk factors. The molecule is based on a 39-amino acid sequence incorporating a C20 fatty diacid moiety that binds albumin, extending its half-life to approximately 5 days and enabling once-weekly subcutaneous dosing.
Key Takeaways: Tirzepatide
- Strongest evidence supports Tirzepatide for superior weight loss and type 2 diabetes control
- Research doses typically range from 2500 to 2500 mcg via subcutaneous injection
- 3 benefits with strong evidence, 3 moderate, 0 preliminary
- Half-life: Approximately 5 days (enabling once-weekly dosing)
- 5 cited research studies in this guide
Mechanism of Action
Tirzepatide simultaneously activates two incretin hormone receptors: GIP-R and GLP-1R. At the GLP-1 receptor, it mimics the effects of native GLP-1 — enhancing glucose-dependent insulin secretion, suppressing glucagon release, slowing gastric emptying, and reducing appetite through hypothalamic signaling. At the GIP receptor, it activates complementary pathways that enhance insulin secretion, improve insulin sensitivity in adipose tissue, and may promote more favorable fat metabolism and distribution. The dual mechanism creates additive metabolic effects: GLP-1R activation provides potent appetite suppression and glycemic control, while GIP-R activation contributes additional insulin sensitization and may modulate central appetite circuits through distinct hypothalamic pathways. Tirzepatide has biased agonism at GIP-R (preferring cAMP signaling over beta-arrestin recruitment), which may contribute to its efficacy profile. The C20 fatty diacid modification enables non-covalent albumin binding in circulation, dramatically extending the half-life from minutes (native incretins) to approximately 5 days. Weight loss is mediated through central appetite suppression (reduced caloric intake), slowed gastric emptying (enhanced satiety), and improved metabolic partitioning favoring fat oxidation over storage.
Research Benefits
Tirzepatide at a Glance
Tirzepatide simultaneously activates two incretin hormone receptors: GIP-R and GLP-1R.
Superior Weight Loss
Strong EvidenceSURMOUNT-1 trial demonstrated up to 22.5% body weight reduction at the highest dose (15 mg) over 72 weeks, the largest weight loss achieved by any approved pharmaceutical agent in clinical trials.
Type 2 Diabetes Control
Strong EvidenceSURPASS trials showed HbA1c reductions of up to 2.58% and up to 50% of patients achieving HbA1c below 5.7% (normal range). Superior to semaglutide 1 mg in head-to-head comparison (SURPASS-2).
Improved Insulin Sensitivity
Strong EvidenceThe dual GIP/GLP-1 mechanism improves insulin sensitivity beyond what GLP-1-only agonists achieve, with particular benefits in adipose tissue insulin signaling.
Cardiovascular Risk Reduction
Moderate EvidenceClinical data shows significant improvements in cardiovascular risk factors including blood pressure, triglycerides, and inflammatory markers. Dedicated cardiovascular outcome data is emerging.
Fatty Liver Improvement
Moderate EvidenceStudies show significant reductions in liver fat content and improvement in NASH/NAFLD markers, likely through combined weight loss and direct metabolic effects.
Obstructive Sleep Apnea
Moderate EvidenceSURMOUNT-OSA trial showed tirzepatide significantly reduced apnea-hypopnea index (AHI) in adults with obesity and moderate-to-severe obstructive sleep apnea.
Research Dosing Protocols
Research Purposes Only: All content is for informational and research purposes only. This site does not provide medical advice, diagnosis, or treatment. Consult a qualified healthcare professional before using any peptide or supplement.
| Research Protocol | Dose Range | Route |
|---|---|---|
| Starting dose | 2500–2500 mcg | Subcutaneous injection |
| Escalation doses | 5000–10000 mcg | Subcutaneous injection |
| Maximum dose | 15000–15000 mcg | Subcutaneous injection |
Frequency
Once weekly
Timing
Any time of day, with or without meals. Same day each week preferred.
Cycle Length
Ongoing; chronic treatment for sustained weight management
Research Notes
- 1Standard dose escalation: 2.5 mg × 4 weeks → 5 mg → 7.5 mg → 10 mg → 12.5 mg → 15 mg.
- 2Each dose level is maintained for at least 4 weeks before escalation.
- 3Gradual escalation is critical to minimize GI side effects (nausea, vomiting).
- 4Mounjaro and Zepbound are the same molecule with different indications and labeling.
- 5Available as pre-filled single-dose pen injectors in the approved pharmaceutical form.
- 6Weight regain is common after discontinuation — treatment is typically long-term.
- 7Monitor for pancreatitis, thyroid C-cell tumors (boxed warning), and gallbladder events.
Reconstitution Guide
Standard Reconstitution
Vial Size
5 mg
Bacteriostatic Water
1 mL
Concentration
50 mcg
per 0.1 mL (10 units)
Step-by-Step Guide
Gather Materials
Tirzepatide vial, bacteriostatic water, alcohol swabs, insulin syringes.
Equilibrate Temperature
Remove the vial from storage and allow it to reach room temperature (5-10 minutes).
Sanitize
Swab the rubber stopper of both the peptide vial and bacteriostatic water vial with alcohol.
Draw Water
Draw 1 mL of bacteriostatic water into a syringe.
Add Water to Vial
Insert the needle into the peptide vial and direct the water stream against the glass wall — not directly onto the powder.
Mix Gently
Swirl the vial gently until the powder is fully dissolved. Never shake. The solution should be clear and colorless.
Store Properly
Refrigerate at Refrigerated (2-8°C / 36-46°F). Approved product: store in refrigerator until use.. Approved product: use by expiration date on pen. Compounded preparations vary..
Storage Temperature
Refrigerated (2-8°C / 36-46°F). Approved product: store in refrigerator until use.
Shelf Life
Approved product: use by expiration date on pen. Compounded preparations vary.
Important Notes
- •Mounjaro/Zepbound comes as pre-filled single-dose pen injectors; no reconstitution needed.
- •Compounded tirzepatide may require reconstitution from lyophilized powder.
- •If using compounded product, reconstitute with bacteriostatic water per provider instructions.
- •Do not freeze reconstituted solution.
- •Protect from light and extreme temperatures.
Tirzepatide Dosing Calculator
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Tirzepatide Reconstitution Calculator
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Safety & Side Effects
Reported Side Effects
- !Nausea (most common, 12-33% depending on dose, usually improves with continued use)
- !Diarrhea (12-21%)
- !Vomiting (5-13%)
- !Decreased appetite (expected pharmacological effect)
- !Constipation (6-11%)
- !Abdominal pain
- !Injection site reactions (mild)
- !Dyspepsia / acid reflux
- !Fatigue
- !Pancreatitis (rare but serious, seek immediate medical attention)
- !Gallbladder events (cholelithiasis, cholecystitis)
- !Boxed warning: thyroid C-cell tumors (observed in rodents, relevance to humans unknown)
Potential Interactions
- ⚡Slows gastric emptying — may affect absorption of oral medications. Take time-sensitive oral medications 1 hour before tirzepatide.
- ⚡May increase the risk of hypoglycemia when combined with insulin or sulfonylureas, dose reduction of these agents may be needed.
- ⚡Oral contraceptives: switch to non-oral contraception or barrier method for 4 weeks after initiation and each dose escalation due to delayed gastric emptying.
- ⚡Not recommended with other GLP-1 receptor agonists (overlapping mechanism, increased GI risk).
- ⚡Caution with medications that cause nausea or GI effects (additive).
- ⚡Monitor warfarin INR more closely due to potential absorption changes.
Important: Side effects and interactions listed here are compiled from published research and community reports. This is not a complete list. No formal drug interaction studies have been conducted for most research peptides. Always consult a qualified healthcare provider.
Research Studies
The following studies are referenced in this profile. PubMed IDs are provided where available for independent verification.
Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1)
Landmark Phase III trial showing tirzepatide achieved 15 mg dose produced 22.5% mean weight reduction at 72 weeks in adults with obesity, with 63% of participants losing ≥20% body weight.
Tirzepatide versus semaglutide in type 2 diabetes (SURPASS-2)
Head-to-head trial demonstrating tirzepatide superiority over semaglutide 1 mg for both HbA1c reduction and weight loss in type 2 diabetes, establishing the advantage of dual incretin agonism.
Tirzepatide for type 2 diabetes (SURPASS-1)
Monotherapy trial showing tirzepatide produced HbA1c reductions of up to 2.07% and weight loss of up to 9.5 kg over 40 weeks, with 31-52% of patients achieving normoglycemia.
Tirzepatide and obstructive sleep apnea (SURMOUNT-OSA)
Showed tirzepatide significantly reduced the severity of obstructive sleep apnea as measured by AHI, demonstrating clinical benefits extending beyond weight loss and glycemic control.
GIP and GLP-1 receptor dual agonism: mechanistic basis for tirzepatide
thorough review of the dual incretin mechanism, explaining how simultaneous GIP and GLP-1 receptor activation produces additive metabolic benefits beyond single-receptor agonists.
Note: This is not an exhaustive list of all published research. Studies are selected for relevance and quality. Click PubMed IDs to verify sources independently. Inclusion does not imply endorsement of the peptide for any clinical use.
Frequently Asked Questions
Tirzepatide is a first-in-class dual GIP/GLP-1 receptor agonist; a once-weekly injectable peptide that activates two incretin hormone receptors simultaneously. It is FDA-approved as Mounjaro (diabetes) and Zepbound (weight loss).
In the head-to-head SURPASS-2 trial, tirzepatide was superior to semaglutide 1 mg for both blood sugar control and weight loss. Tirzepatide's dual mechanism (GIP + GLP-1) appears to provide greater efficacy than GLP-1-only agonists like semaglutide.
In the SURMOUNT-1 trial, the average weight loss at the highest dose (15 mg) was 22.5% of body weight over 72 weeks. About 63% of participants lost 20% or more of their body weight. Results vary by individual.
Mounjaro and Zepbound contain the same molecule (tirzepatide) at the same doses. Mounjaro is approved for type 2 diabetes, while Zepbound is approved for chronic weight management. The distinction is primarily in indication and insurance coverage.
Nausea is the most common side effect and usually improves over time. Key strategies include slow dose escalation (stay at each dose for 4+ weeks), eating smaller meals, avoiding high-fat foods, staying hydrated, and not lying down immediately after eating. Your healthcare provider may adjust the escalation schedule.
Clinical trials show approximately 25-40% of weight lost is lean mass (typical for any weight loss method). Adequate protein intake (1.0-1.6 g/kg/day) and resistance training during treatment are strongly recommended to preserve muscle mass.
Weight regain is common after discontinuation. The SURMOUNT-4 trial showed participants who switched from tirzepatide to placebo regained approximately two-thirds of their lost weight over 52 weeks. Ongoing treatment is typically needed to maintain weight loss.
Research & Educational Use Only
All content is for informational and research purposes only. This site does not provide medical advice, diagnosis, or treatment. Consult a qualified healthcare professional before using any peptide or supplement.
The information presented here is compiled from published research studies and is intended for informational purposes only. Individual results may vary. Always consult with a licensed healthcare provider.