What is a GLP-1 receptor agonist, and why do different drugs have so many names?
GLP-1 stands for glucagon-like peptide-1, an incretin hormone produced in the gut in response to food intake. It signals the pancreas to release insulin in a glucose-dependent manner, slows gastric emptying, and acts on hypothalamic satiety circuits to reduce appetite. GLP-1 receptor agonists are synthetic peptide molecules that bind to and activate the GLP-1 receptor, mimicking and extending these effects.
The first generation of GLP-1 drugs was developed primarily for glycemic management. More recent agents, including once-weekly formulations with longer half-lives, are prescribed for weight management support in adults with obesity or excess body weight with a weight-related comorbidity. These are not over-the-counter supplements — they are prescription medications dispensed by licensed pharmacies under clinician oversight.
| Generic name | Brand name(s) | Primary indication | Frequency |
|---|---|---|---|
| Semaglutide | Ozempic, Wegovy, Rybelsus | T2D / weight management / oral T2D | Weekly (inj); daily (oral) |
| Tirzepatide | Mounjaro, Zepbound | T2D / weight management | Weekly |
| Liraglutide | Victoza, Saxenda | T2D / weight management | Daily |
| Dulaglutide | Trulicity | T2D | Weekly |
| Exenatide | Byetta, Bydureon | T2D | Twice daily / weekly (ER) |
Semaglutide: Ozempic, Wegovy, and Rybelsus
Semaglutide is probably the GLP-1 name you have heard most. The generic name is semaglutide; the brand names vary by formulation and indication:
- Ozempic — injectable semaglutide, FDA-approved for glycemic management in adults with type 2 diabetes and for cardiovascular risk reduction in adults with type 2 diabetes and cardiovascular disease. Manufactured by Novo Nordisk. Administered once weekly via subcutaneous injection.
- Wegovy — injectable semaglutide at a higher maintenance dose (2.4 mg), FDA-approved for chronic weight management in adults with obesity or overweight with at least one weight-related condition. Same active molecule as Ozempic; the approved indication and dosing protocol differ.
- Rybelsus — oral semaglutide, the first GLP-1 receptor agonist approved for oral administration. Lower bioavailability than injectable formulations; approved for glycemic management in adults with type 2 diabetes.
- Compounded semaglutide — during the period semaglutide was listed on the FDA drug shortage list, licensed 503A compounding pharmacies could prepare semaglutide for individual patients with a valid clinician prescription. Compounded semaglutide is not an FDA-approved drug and is not equivalent to Ozempic or Wegovy in a regulatory sense. It is compounded in the USA by licensed 503A pharmacies — no hidden overseas supply chain.
Tirzepatide: Mounjaro and Zepbound
Tirzepatide is a dual-receptor agonist — it activates both the GLP-1 receptor and the GIP (glucose-dependent insulinotropic polypeptide) receptor. That dual mechanism is structurally distinct from semaglutide, which is GLP-1-only. Both approved brand names contain the same active molecule:
- Mounjaro — tirzepatide FDA-approved for glycemic management in adults with type 2 diabetes. Manufacturer: Eli Lilly.
- Zepbound — tirzepatide FDA-approved for chronic weight management. Same molecule as Mounjaro; the labeled indication and prescribing context differ.
- Compounded tirzepatide — similarly available through licensed 503A compounding pharmacies when listed on shortage. Compounded formulations are not FDA-approved finished drug products.
In head-to-head clinical data (the SURPASS-2 trial), tirzepatide produced greater average reductions in body weightcompared to semaglutide. Individual responses vary significantly; a clinician review is the right context to evaluate which agent may fit a given patient’s situation.
One molecule, several names: Ozempic and Wegovy are both semaglutide; Mounjaro and Zepbound are both tirzepatide.
Liraglutide: Victoza and Saxenda
Liraglutide was among the first once-daily injectable GLP-1 receptor agonists approved in the US. Like semaglutide, it carries two brand names tied to different dosing and indications:
- Victoza — liraglutide 1.2 mg or 1.8 mg once daily, approved for glycemic management in type 2 diabetes and for cardiovascular risk reduction in adults with type 2 diabetes and high cardiovascular risk.
- Saxenda — liraglutide 3.0 mg once daily, approved for chronic weight management. Also approved for weight management in adolescents aged 12 and older with obesity.
Liraglutide requires daily injection versus the once-weekly dosing of semaglutide or tirzepatide. For most patients, adherence is easier with a weekly schedule.
Other GLP-1 receptor agonist names
The GLP-1 drug class includes additional agents, some with longer histories in clinical practice:
- Dulaglutide (Trulicity) — once-weekly subcutaneous injection approved for glycemic management and cardiovascular risk reduction in type 2 diabetes. Not currently approved for weight management as a primary indication.
- Exenatide (Byetta / Bydureon) — one of the earliest approved GLP-1 drugs. Byetta is twice-daily; Bydureon (now Bydureon BCise) is an extended-release once-weekly formulation. Used in glycemic management for type 2 diabetes.
- Albiglutide (Tanzeum) — once-weekly injection for glycemic management; withdrawn from the US market in 2018 for business reasons, not safety concerns.
- Lixisenatide (Adlyxin) — once-daily injection; withdrawn from the US market in 2019.
For weight management specifically, the agents with the most robust clinical data and current availability are semaglutide (Wegovy / compounded) and tirzepatide (Zepbound / compounded).
What does “compounded GLP-1” actually mean?
When a clinician prescribes “compounded semaglutide” or “compounded tirzepatide,” they are prescribing a medication prepared by a licensed 503A compounding pharmacy from the same active pharmaceutical ingredient used in branded products. Several points matter:
- Compounded formulations are not FDA-approved drugs and should never be characterized as such. The FDA approval status applies to the branded finished drug product, not to compounded versions.
- 503A compounding is patient-specific: a licensed pharmacist compounds the medication based on a valid individual prescription, not for large-scale distribution.
- Quality depends on the pharmacy. Working through a telehealth clinician who partners with vetted, licensed 503A compounding pharmacies is meaningfully different from purchasing from unverified online sources.
PepScribe works with licensed 503A compounding pharmacies only. No hidden overseas supply chain.
Frequently asked questions
What are the main GLP-1 receptor agonist names?
The most widely recognized GLP-1 receptor agonist drug names include semaglutide (brand names Ozempic and Wegovy), tirzepatide (Mounjaro and Zepbound), liraglutide (Victoza and Saxenda), dulaglutide (Trulicity), and exenatide (Byetta and Bydureon). Each differs in molecular structure, dosing schedule, and labeled indication.
Is semaglutide a GLP-1 drug?
Yes. Semaglutide is a GLP-1 receptor agonist — a synthetic peptide analog of the glucagon-like peptide-1 hormone. It is available as branded injectable products and, through licensed 503A compounding pharmacies, as a compounded formulation prescribed by clinicians for weight management support.
What is the difference between semaglutide and tirzepatide?
Semaglutide is a single-receptor GLP-1 agonist. Tirzepatide is a dual GIP/GLP-1 receptor agonist, meaning it activates both the glucose-dependent insulinotropic polypeptide (GIP) receptor and the GLP-1 receptor. Clinical trials show tirzepatide generally produces greater average body-weight reductions in head-to-head data.
Are compounded GLP-1 medications the same as the brand-name drugs?
Compounded semaglutide and tirzepatide contain the same active peptide as the branded versions. However, compounded formulations are not FDA-approved finished drug products — they are prepared by licensed 503A compounding pharmacies based on a clinician prescription, and are not interchangeable with the FDA-approved brands in a regulatory sense.
What GLP-1 names refer to the same drug?
Ozempic and Wegovy are two brand names for semaglutide (injectable). Rybelsus is oral semaglutide. Mounjaro and Zepbound are both tirzepatide — Mounjaro carries a diabetes indication, Zepbound a weight-management indication. Victoza and Saxenda are both liraglutide.
Can I get a compounded GLP-1 with a clinician prescription?
During periods when branded GLP-1 products are on the FDA drug shortage list, licensed 503A compounding pharmacies may prepare compounded versions for individual patients with a valid clinician prescription. A clinician evaluates eligibility, writes the prescription, and monitors the patient through the course of treatment.