Tirzepatide
Tirzepatide (Dual GIP/GLP-1 Receptor Agonist)
The dual-action GLP-1 that outperforms Ozempic in every trial
Tirzepatide is a dual GIP/GLP-1 receptor agonist that has shown up to 20.9% body weight reduction in clinical trials - surpassing semaglutide in head-to-head comparisons.
Admin routes
Subcutaneous
Popularity
High
Side effects
Monitor closely
AU vendors
2 rated
✓Key benefits
📈What to expect
Reduced appetite; GI side effects most common early
5–8% body weight loss; blood glucose improvement
10–15% body weight loss; A1C normalisation
Up to 22.5% total body weight loss in trials
Based on community reports and published research. Individual results vary significantly.
💊Dosing protocols
Weight management (Zepbound)
Start 2.5 mg, titrate to 10–15 mg
Once weekly (subcutaneous)
Ongoing (titrate over 20+ weeks)
Type 2 diabetes (Mounjaro)
Start 2.5 mg, titrate to 5–15 mg
Once weekly (subcutaneous)
Ongoing
Dosing information is sourced from published research and community protocols. This is not a recommendation. Consult a healthcare professional.
Research status|FDA-approved - Phase 3 human data (SURMOUNT/SURPASS programs)
Overview
Tirzepatide (brand names Mounjaro for diabetes, Zepbound for weight management) is a first-in-class dual GIP/GLP-1 receptor agonist developed by Eli Lilly. Unlike semaglutide which only targets GLP-1 receptors, tirzepatide also activates GIP (glucose-dependent insulinotropic polypeptide) receptors, creating a synergistic effect on appetite, insulin sensitivity, and fat metabolism. The SURMOUNT-1 trial demonstrated average weight loss of 20.9% at the highest dose - the most ever achieved by a pharmaceutical agent in a clinical trial. It received FDA approval for type 2 diabetes in 2022 and for weight management in 2023.
⚙️How it works
Tirzepatide simultaneously activates both GIP and GLP-1 receptors. GLP-1 receptor activation reduces appetite, slows gastric emptying, and stimulates insulin secretion. GIP receptor activation enhances fat metabolism, improves insulin sensitivity, and may protect against the muscle wasting seen with GLP-1-only agonists. The dual mechanism produces greater weight loss than GLP-1 alone. The molecule is engineered with a C20 fatty acid moiety that binds to albumin, providing a half-life of approximately 5 days for once-weekly dosing.
⚡Side effects
📅Research history
Phase 2 trial results show superior weight loss to semaglutide
FDA approves Mounjaro for type 2 diabetes
SURMOUNT trials show up to 22.5% body weight loss
FDA approves Zepbound for chronic weight management
Compounded tirzepatide becomes widely available
🏪Rated vendors (Australia)
View all →LotusLabs
Australia · 99%+ (HPLC and mass spectrometry) purity · Same-day dispatch, 2–3 days delivery
lotuslabs.com.au ↗The Peptide Co
Australia (multiple depots) · 99%+ (in-house QC) purity · Same-day dispatch, 1–3 days delivery
thepeptideco.com ↗Vendor ratings are based on community feedback and are not endorsements. Always verify third-party certificates of analysis (CoA) and check current Australian regulations before purchasing.
Tirzepatide vs semaglutide
In the SURMOUNT trials, tirzepatide at its highest dose (15 mg) produced average weight loss of 20.9% compared to semaglutide's 16.9% in the STEP trials. A head-to-head trial (SURMOUNT-5) is expected to provide direct comparison data. Beyond weight, tirzepatide appears to produce greater improvements in insulin sensitivity and may better preserve lean mass due to the GIP receptor component. The GI side effect profile is similar between the two, though some data suggests tirzepatide may cause slightly less nausea at equivalent efficacy levels.
Retatrutide: the triple agonist
Retatrutide is the next evolution - a triple GIP/GLP-1/glucagon receptor agonist in Phase 3 trials. Early data showed up to 24.2% weight loss at 48 weeks. The glucagon receptor component may further enhance fat metabolism and energy expenditure. If approved, it would represent the most potent pharmaceutical weight loss agent ever developed. Eli Lilly is running the Phase 3 program with results expected in 2025–2026.
References
- [1]Jastreboff AM, et al. "Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1)." New England Journal of Medicine, 2022.
- [2]Frias JP, et al. "Tirzepatide versus semaglutide once weekly in patients with type 2 diabetes." New England Journal of Medicine, 2021.
- [3]Rosenstock J, et al. "Retatrutide, a GIP, GLP-1, and glucagon receptor agonist." New England Journal of Medicine, 2023.
Frequently asked questions
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Open CalculatorDisclaimer: This guide is for educational and informational purposes only. It is not medical advice. The dosing protocols listed are sourced from published research and community reports and do not constitute a recommendation. Always consult a qualified healthcare professional before using any peptide. Australian regulations classify many peptides as Schedule 4 (prescription-only) substances. Check current TGA guidelines before purchasing.