Semaglutide vs Tirzepatide vs Retatrutide: 3-Way Research Comparison

Three peptides currently dominate metabolic-research conversations: Semaglutide (single GLP-1 agonist), Tirzepatide (dual GLP-1 + GIP), and Retatrutide (triple GLP-1 + GIP + glucagon). This guide compares them head-to-head on receptor mechanism, research-stage dosing patterns, reconstitution, stability, and sourcing — so researchers can match the right compound to the right study design.

Receptor agonism at a glance

Mechanisms — what each peptide does

Semaglutide

A GLP-1 receptor agonist that mimics the endogenous incretin hormone GLP-1. Research literature describes effects on glucose-dependent insulin secretion, delayed gastric emptying, and satiety pathways. Half-life is engineered to be long enough for once-weekly dosing in study contexts.

Tirzepatide

A dual GLP-1 + GIP receptor agonist. The added GIP activity is studied for synergistic effects on glucose handling and adipose tissue signaling. Several head-to-head studies suggest tirzepatide produces stronger composite metabolic effects than semaglutide in research models.

Retatrutide

A triple agonist of GLP-1, GIP, and glucagon receptors. The glucagon activity is studied for direct effects on energy expenditure and lipolysis. Retatrutide is the newest compound in this trio and is under active investigation in research-stage trials.

Research-stage dosing patterns

These ranges reflect commonly cited research-stage starting points — not clinical guidance. Always use the Prax peptide calculator to translate research goals into exact concentration math.

• Semaglutide: studies commonly start at 0.25 mg/week, escalating in 4-week steps
• Tirzepatide: studies commonly start at 2.5 mg/week, with monthly step-ups
• Retatrutide: studies have used a wider range, with escalation phases under active investigation

Reconstitution & storage

All three peptides arrive as lyophilized powder. Standard research handling:

1. Add bacteriostatic water (1–3 mL depending on target concentration) slowly down the vial wall
2. Gently swirl — never shake — until fully dissolved
3. Store reconstituted vials at 2–8 °C, protected from light
4. For storage beyond 2–4 weeks, aliquot and freeze at −20 °C or below

For full details, see our peptide storage guide.

Purity & verification

Every Prax Peptides batch of Semaglutide, Tirzepatide, and Retatrutide is third-party tested via HPLC and mass spectrometry to verify ≥99% purity. Certificates of analysis are available per lot.

Which to choose for which study

• Receptor specificity — Semaglutide is the cleanest single-receptor study tool
• Composite metabolic response — Tirzepatide adds GIP synergy
• Energy expenditure pathways — Retatrutide's glucagon arm extends the research scope

Order the research peptide that fits your study

• Semaglutide 5mg →
• Tirzepatide 10mg →
• Retatrutide (Reta GLP-3R) 10mg →