GLP-1 Peptide Research in Australia: Tirzepatide, Retatrutide & Semaglutide

GLP-1 (Glucagon-Like Peptide-1) is an incretin hormone produced in the gut in response to food intake. Its primary physiological roles include:

• Stimulating glucose-dependent insulin secretion from pancreatic beta cells
• Suppressing glucagon release, reducing hepatic glucose output
• Slowing gastric emptying, reducing post-meal glucose spikes
• Acting on hypothalamic satiety centres to reduce appetite and food intake

Native GLP-1 has a half-life of only 1–2 minutes in circulation due to rapid degradation by DPP-4 enzymes. Pharmaceutical development of GLP-1 receptor agonists (GLP-1 RAs) focused on creating DPP-4-resistant analogues, producing compounds like semaglutide, dulaglutide, and the newer dual/triple agonists now dominating metabolic research.

Semaglutide (Ozempic/Wegovy) is a once-weekly GLP-1 receptor agonist with 94% amino acid homology to native GLP-1. The SUSTAIN and STEP clinical trial programmes established semaglutide as a landmark metabolic compound:

• STEP 1 (obesity, non-diabetic): mean body weight reduction of ~14.9% at 68 weeks (2.4mg weekly dose)
• SUSTAIN-6: significant cardiovascular risk reduction in type 2 diabetes

Semaglutide represented a step change in metabolic research and established the template for next-generation incretin peptides. Research-grade semaglutide is available from international suppliers; OzPeps focuses on the next-generation compounds that go beyond GLP-1 single agonism.

Tirzepatide (Mounjaro/Zepbound, Eli Lilly) is a dual GLP-1 and GIP (glucose-dependent insulinotropic polypeptide) receptor agonist, the first approved dual incretin agonist. The addition of GIP receptor agonism amplifies insulin secretion and is believed to improve tolerability relative to pure GLP-1 agonists by reducing nausea.

SURMOUNT-1 trial data (72 weeks, non-diabetic obesity): mean body weight reduction of ~20.9% at the 15mg dose, substantially exceeding semaglutide outcomes. Tirzepatide is FDA-approved for both type 2 diabetes and obesity.

Research-grade Tirzepatide from OzPeps allows Australian researchers to study dual incretin agonism without the cost and regulatory complexity of pharmaceutical procurement. View Tirzepatide →

Retatrutide (LY3437943, Eli Lilly) is a triple agonist adding glucagon receptor activation to the GLP-1 + GIP profile of Tirzepatide. The glucagon component drives thermogenesis and energy expenditure, a mechanism absent in tirzepatide, which research suggests may explain Retatrutide's larger weight loss outcomes in Phase 2 data.

Phase 2 NEJM trial (48 weeks, 12mg weekly): mean body weight reduction of ~24.2%, the highest reported in any major incretin peptide trial to date. Phase 3 TRIUMPH programme is underway as of 2025.

Retatrutide is the frontier of GLP-1 research and the most potent triple agonist available for Australian researchers. View Retatrutide →

Summary of key research compounds for Australian metabolic researchers:

• Semaglutide, GLP-1 only; ~15% weight loss; gold standard comparator; FDA approved
• Tirzepatide, GLP-1 + GIP dual; ~21% weight loss; FDA approved; available from OzPeps
• Retatrutide, GLP-1 + GIP + glucagon triple; ~24% weight loss (Phase 2); Phase 3 ongoing; available from OzPeps

For researchers studying the incremental contribution of each receptor pathway to metabolic outcomes, OzPeps' Tirzepatide and Retatrutide allow direct mechanistic comparison of dual versus triple agonism within the same research programme.

GLP-1 receptor agonism has demonstrated effects beyond weight and glucose in preclinical and clinical research:

• Cardiovascular protection, GLP-1 RAs reduce MACE (major adverse cardiovascular events) in high-risk type 2 diabetes populations; mechanism involves direct cardiac and vascular GLP-1 receptor activation
• NAFLD/NASH, hepatic fat reduction is consistently observed; glucagon receptor agonism (Retatrutide) adds additional hepatic fat-clearing mechanisms
• Kidney protection, emerging data from the FLOW trial (semaglutide) demonstrates renal protective effects in CKD
• Neurological applications, GLP-1 receptors are expressed in the brain; research into Alzheimer's and Parkinson's disease is expanding, driven by observations of reduced dementia risk in GLP-1 RA users

OzPeps supplies research-grade GLP-1 pathway peptides Australia-wide with fast dispatch and discreet packaging:

• Tirzepatide 30mg (GLP-1 + GIP) →
• Retatrutide 20mg (GLP-1 + GIP + Glucagon) →

For a side-by-side comparison of the two leading next-generation GLP-1 compounds, see the Retatrutide vs Tirzepatide research guide →

All GLP-1 pathway peptides supplied by OzPeps are for laboratory and in-vitro research purposes only. They are not TGA-approved therapeutic goods and are not intended for human or animal consumption. Researchers are responsible for compliance with all applicable regulations.