Semaglutide
The established benchmark. Well-characterized safety profile and the widest clinical familiarity among prescribers.
Wholesale Sourcing Reference
GLP-1 Agonists: A Comparative Guide for Wholesale Buyers
A clinical reference for licensed compounding pharmacies and med spas evaluating Tirzepatide, Retatrutide, and Semaglutide for their formulary — with a focus on half-life, receptor pharmacology, and efficacy data relevant to wholesale peptide sourcing decisions.
The GLP-1 landscape in 2026
Incretin therapy has moved rapidly beyond first-generation GLP-1 mono-agonists. Today's clinical pipeline spans single-receptor agonists (Semaglutide), dual-agonists (Tirzepatide), and triple-agonists (Retatrutide). For wholesale buyers supplying compounding pharmacies and aesthetic clinics, understanding the pharmacological differences matters — patients respond differently, and prescribers increasingly ask sourcing partners to carry the full spectrum.
Side-by-side comparison
| Peptide | Receptor Target | Half-Life | Efficacy (Weight Reduction) |
|---|---|---|---|
| Semaglutide | GLP-1 receptor agonist | ~7 days (once-weekly dosing) | ~15% mean body-weight reduction at 68 weeks (STEP 1) |
| Tirzepatide | Dual GIP / GLP-1 receptor agonist | ~5 days (once-weekly dosing) | ~20.9% mean body-weight reduction at 72 weeks, 15 mg (SURMOUNT-1) |
| Retatrutide | Triple GIP / GLP-1 / glucagon receptor agonist | ~6 days (once-weekly dosing) | ~24.2% mean body-weight reduction at 48 weeks, 12 mg (Phase 2) |
Tirzepatide
Dual incretin action produces greater weight reduction and glycemic control than pure GLP-1 agonism in head-to-head trials.
Retatrutide
Investigational. Adds glucagon-receptor activity, which appears to drive additional lipolysis and energy expenditure. Phase 3 ongoing.
Half-life & dosing cadence
All three peptides support once-weekly subcutaneous dosing thanks to albumin-binding fatty-acid modifications that extend circulation. Semaglutide has the longest half-life (~7 days), Retatrutide sits in the middle (~6 days), and Tirzepatide clears fastest (~5 days). In practice the differences are clinically small — steady-state is reached in 4–5 weeks for all three — but Semaglutide's slightly longer tail can be useful for patients prone to missed doses.
Efficacy in head-to-head data
SURMOUNT-1 established Tirzepatide's advantage over Semaglutide on weight-loss endpoints, and Retatrutide's Phase 2 program has since produced the largest mean reductions reported to date for a once-weekly incretin. Practitioners typically stratify: Semaglutide for patients new to GLP-1 therapy, Tirzepatide for those needing greater response or dual metabolic benefit, and Retatrutide for research and clinical-trial contexts where its investigational status is appropriate.
Sourcing considerations for wholesale buyers
- Certificates of analysis. Require a third-party COA for every lot — HPLC purity ≥99%, mass spectrometry identity confirmation, and endotoxin limits appropriate for the intended route.
- Chain of custody. Cold-chain handling from synthesis through delivery preserves peptide integrity; gaps show up as aggregation and reduced potency long before visible reconstitution issues.
- Formulary breadth. Carrying all three — Semaglutide, Tirzepatide, and Retatrutide — lets a compounding partner meet prescriber preference without redirecting business to a second supplier.
- Regulatory posture. Retatrutide remains investigational; confirm your jurisdiction's handling of research peptides before ordering at scale.
Request wholesale access
Purity Med Supply serves licensed compounding pharmacies and med spas with third-party tested peptides — every lot's certificate of analysis is provided to verified buyers in the portal as it is published. Pricing is unlocked for verified businesses.
This guide is provided for licensed medical professionals for informational purposes only and does not constitute medical advice. Product availability varies by jurisdiction and regulatory status.