AmericanPeptide
Catalog/Semaglutide
MetabolicFDA Approved

Semaglutide

Also known as Ozempic · Wegovy · Rybelsus

The once-weekly GLP-1 receptor agonist behind Ozempic, Wegovy, and Rybelsus — FDA-approved for type 2 diabetes, chronic weight management, cardiovascular risk reduction, and MASH.

Research refreshed

Overview

Semaglutide is a 31-amino-acid GLP-1 receptor agonist engineered for once-weekly dosing via fatty-acid acylation and amino-acid substitutions that resist DPP-4 degradation. It is FDA-approved for type 2 diabetes (Ozempic, 2017; oral Rybelsus, 2019), chronic weight management (Wegovy, 2021), cardiovascular risk reduction in adults with obesity and established heart disease (2024), and — as of August 2025 — metabolic dysfunction-associated steatohepatitis (MASH) with moderate-to-advanced fibrosis. The STEP-1 obesity trial reported ~14.9% mean weight reduction at 68 weeks.

Background

Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist built on the backbone of human GLP-1. Two engineering changes define it: a C18 fatty-diacid chain attached through a linker that promotes reversible binding to albumin, and amino-acid substitutions that resist degradation by the enzyme DPP-4. Together these extend its half-life to roughly a week, enabling once-weekly administration. An oral formulation (Rybelsus) co-formulates the peptide with the absorption enhancer SNAC to protect it through the stomach.

Its pivotal data anchor the modern incretin era. The STEP-1 trial (Wilding et al., NEJM 2021, PMID 33567185) reported −14.9% mean body-weight change at 68 weeks on the 2.4 mg dose versus −2.4% on placebo — roughly 70% of participants lost at least 10% of body weight. The SELECT cardiovascular-outcomes trial reported a 20% reduction in major adverse cardiovascular events in adults with overweight or obesity and established cardiovascular disease but without diabetes, leading to a dedicated CV indication in 2024; the SOUL trial (McGuire et al., NEJM 2025, PMID 40162642) then showed the oral formulation cuts MACE by 14% in high-risk type 2 diabetes.

The liver program is the most recent expansion. The ESSENCE Phase 3 trial (Sanyal et al., NEJM 2025, PMID 40305708) reported resolution of steatohepatitis without worsening of fibrosis in 62.9% of participants on semaglutide 2.4 mg versus 34.3% on placebo at 72 weeks, and in August 2025 the FDA granted accelerated approval of Wegovy for noncirrhotic MASH with moderate-to-advanced fibrosis. Semaglutide’s acylation-plus-DPP-4-resistance template now informs the entire incretin class — dual agonists like tirzepatide and triple agonists like retatrutide are its molecular descendants.

Mechanism

GLP-1 receptor agonism → glucose-dependent insulin secretion, glucagon suppression, slowed gastric emptying, and central appetite suppression.

Key research findings

  • Weight management — STEP-1 (NEJM 2021) reported −14.9% mean weight reduction at 68 weeks (2.4 mg) versus −2.4% placebo; ~70% of participants lost ≥10% of body weight.
  • Cardiovascular outcomes — SELECT reported a 20% MACE reduction in obesity with established CVD (no diabetes); SOUL (NEJM 2025) reported a 14% MACE reduction for oral semaglutide in high-risk type 2 diabetes.
  • MASH — ESSENCE Phase 3 (NEJM 2025) reported 62.9% steatohepatitis resolution versus 34.3% placebo; FDA accelerated approval for MASH followed in August 2025.
  • Glycemic control — the original approved use: glucose-dependent insulin secretion and glucagon suppression in type 2 diabetes (SUSTAIN program).
  • Half-life engineering — fatty-acid acylation and DPP-4-resistant substitutions extend the half-life to ~1 week; the oral form adds the SNAC absorption enhancer.

How Semaglutide is made

Behind every vial of Semaglutide is the same exacting pipeline every research peptide runs — but the chemistry plays out differently for this molecule. Here is how Semaglutide, specifically, is brought into being.

  1. On paper first

    On paper, Semaglutide is C187H291N45O59 — about 4,113.6 daltons of precisely arranged atoms. Before a single bond is made, the target sequence, salt form, and purity threshold are written down as the contract the finished material must meet.

  2. Built residue by residue

    Semaglutide is assembled by solid-phase peptide synthesis — the chain grows one protected residue at a time on resin, and what you fail to build cleanly here you pay to remove later. It also carries fatty-acid acylation, an extra step beyond a plain chain that adds both capability and cost.

  3. Purity is won here

    The crude mixture — Semaglutide plus its deletions and side products — is then separated on preparative HPLC, and where the cut is taken decides the difference between a genuinely pure peptide and a barely-passable one.

  4. Proven, then protected

    A real batch of Semaglutide proves itself: identity confirmed by mass spectrometry against its ~4,113.6 Da, purity read directly off an analytical HPLC trace, water and counterion content measured. That batch-specific certificate of analysis is the only honest way to know what is actually in a vial of Semaglutide — and a short, cold, accountable chain of custody is how that purity survives the trip to your bench.

Walk the full synthesis pipeline

Handling, storage & why purity is hard

Beyond its 31-residue chain, semaglutide carries a fatty-diacid side chain on a linker — extra synthetic steps that each add cost and another opportunity for impurities to form. Genuine material is purified to a defined spec and documented on a certificate of analysis, never judged by appearance.

Storage
Lyophilized: store frozen and protected from light; stable for extended periods. Reconstituted: refrigerate at 2–8 °C and use within weeks, not months.
Handling
Reconstitute gently — swirl rather than shake, since agitation can shear the peptide. Protect from heat and minimize freeze–thaw cycles.

Don't judge a vial by its cake. A fluffy, good-looking lyophilized powder reflects bulking agents and freeze-drying parameters — not purity. Insist on a batch-specific certificate of analysis.

How peptides are made — the full pipeline

Research areas

  • Type 2 diabetes
  • Obesity
  • MASH
  • Cardiovascular risk reduction

Research-area guides

Latest research

Recent clinical trials and publications mentioning Semaglutide, pulled automatically from ClinicalTrials.gov and PubMed and refreshed daily. Listings are unfiltered search results, not curated endorsements.

Recent trials

Recent publications

Frequently asked questions

What is semaglutide?+

Semaglutide is a long-acting GLP-1 receptor agonist FDA-approved for type 2 diabetes (Ozempic, Rybelsus), chronic weight management (Wegovy), cardiovascular risk reduction in obesity with established heart disease, and — since August 2025 — MASH with moderate-to-advanced fibrosis.

How much weight do people lose on semaglutide?+

In the pivotal STEP-1 trial (NEJM 2021), adults on semaglutide 2.4 mg lost a mean of 14.9% of body weight at 68 weeks versus 2.4% on placebo; about 70% lost at least 10%, and about half lost at least 15%. These are trial population means, not individual predictions.

What is the difference between Ozempic, Wegovy, and Rybelsus?+

All three are semaglutide. Ozempic (weekly injection) and Rybelsus (daily oral tablet) are approved for type 2 diabetes; Wegovy (weekly injection, higher 2.4 mg dose) is approved for chronic weight management, cardiovascular risk reduction, and MASH. This page is a research reference, not medical advice.

Is semaglutide approved for fatty liver (MASH)?+

Yes — in August 2025 the FDA granted accelerated approval of Wegovy for adults with noncirrhotic MASH and moderate-to-advanced liver fibrosis, based on the ESSENCE Phase 3 trial (62.9% steatohepatitis resolution versus 34.3% placebo at 72 weeks).

What are the side effects of semaglutide?+

The most common adverse events in trials are gastrointestinal — nausea, vomiting, diarrhea, and constipation — usually during dose escalation. The label carries a boxed warning about thyroid C-cell tumors seen in rodent studies. This page is a research reference, not medical advice.

Why is semaglutide dosed once weekly?+

A fatty-diacid side chain lets it bind reversibly to albumin, and amino-acid substitutions resist breakdown by the enzyme DPP-4 — together stretching GLP-1’s natural minutes-long half-life to about one week.

How does semaglutide compare to tirzepatide and retatrutide?+

Semaglutide activates GLP-1 alone; tirzepatide adds GIP (dual agonist, ~22.5% mean weight loss in SURMOUNT-1) and retatrutide adds both GIP and glucagon (triple agonist, ~28.7% in the first Phase 3 readout). Cross-trial comparisons are not head-to-head; semaglutide remains the most extensively studied and broadly approved of the three.

Is semaglutide a peptide?+

Yes — a 31-residue analog of human GLP-1 (~4,113.6 Da) built by solid-phase synthesis, with a C18 fatty-diacid chain on a linker attached to a lysine. The oral Rybelsus form co-formulates the same peptide with the SNAC absorption enhancer.

Related peptides

Peptide Agent

Ask the Agent about Semaglutide

Dosing protocols, mechanism, comparisons, and the latest trials — citation-backed answers grounded in PubMed, PubChem, and ClinicalTrials.gov.