What are GLP-1 receptor agonists?
GLP-1 (glucagon-like peptide-1) is a gut hormone released after eating. It signals the pancreas to release insulin, tells the brain to reduce appetite, and slows gastric emptying. GLP-1 receptor agonists are synthetic molecules engineered to bind GLP-1 receptors with greater potency and a much longer half-life than the endogenous hormone — long enough for once-weekly injection in most modern formulations.
Tirzepatide, the dual agonist, adds a second mechanism: it also activates GIP (glucose-dependent insulinotropic polypeptide) receptors, adding a distinct pathway for insulin secretion and adipose tissue regulation. This dual mechanism is why tirzepatide trials showed modestly greater average weight reduction than semaglutide trials, though direct head-to-head comparative data are limited.
What are all the FDA-approved GLP-1 medications?
Semaglutide-based
- Ozempic (semaglutide 0.5 mg, 1 mg, 2 mg weekly injection) — FDA-approved for glycemic management in adults with type 2 diabetes. Widely prescribed off-label for weight management.
- Wegovy (semaglutide 2.4 mg weekly injection) — FDA-approved for chronic weight management in adults with BMI ≥30, or ≥27 with a weight-related comorbidity.
- Rybelsus (oral semaglutide 3 mg, 7 mg, 14 mg daily tablet) — FDA-approved for glycemic management in adults with type 2 diabetes. The only oral GLP-1 receptor agonist.
Tirzepatide-based (GLP-1 + GIP dual agonist)
- Mounjaro (tirzepatide 2.5–15 mg weekly injection) — FDA-approved for glycemic management in adults with type 2 diabetes.
- Zepbound (tirzepatide 2.5–15 mg weekly injection) — FDA-approved for chronic weight management in adults with BMI ≥30, or ≥27 with a weight-related comorbidity.
Liraglutide-based
- Victoza (liraglutide 1.2 mg, 1.8 mg daily injection) — FDA-approved for type 2 diabetes management and cardiovascular risk reduction.
- Saxenda (liraglutide 3 mg daily injection) — FDA-approved for chronic weight management in adults and adolescents.
Exenatide-based
- Byetta (exenatide 5 mcg, 10 mcg twice daily injection) — FDA-approved for type 2 diabetes management.
- Bydureon / Bydureon BCise (exenatide extended-release 2 mg weekly injection) — FDA-approved for type 2 diabetes management.
Dulaglutide-based
- Trulicity (dulaglutide 0.75–4.5 mg weekly injection) — FDA-approved for type 2 diabetes management and cardiovascular risk reduction.
What compounded GLP-1 medications are available?
Compounded semaglutide and compounded tirzepatide are available through licensed 503A compounding pharmacies under specific conditions: the branded commercial product must be on the FDA drug shortage list at the time of dispensing. Compounded preparations use pharmaceutical-grade API and must be prepared under USP compounding standards, but they are not FDA-approved as finished drug products.
Practically speaking, compounded versions have been significantly more accessible than branded products for many patients — lower cost (no insurance gatekeeping), faster access, and consistent supply in the period when branded product availability was constrained.
The regulatory basis for compounded semaglutide and tirzepatide is dynamic: it is tied to shortage status and can change. Patients should confirm current regulatory status with their prescribing clinician.
What’s available through PepScribe
- Compounded semaglutide — subcutaneous injection, dispensed by licensed 503A pharmacies in the USA
- Compounded tirzepatide — subcutaneous injection, dispensed by licensed 503A pharmacies in the USA
Both require a licensed clinician to review your intake and issue a valid prescription. No hidden overseas supply chain — compounded in the USA.
How do you choose between GLP-1 medications?
Patients often ask whether semaglutide or tirzepatide is “better.” The honest answer from the clinical literature:
- Both produce clinically meaningful weight reduction in eligible adults in the context of a comprehensive weight management approach.
- SURMOUNT-1 (tirzepatide) and STEP-1 (semaglutide) trials showed different average outcomes, but direct head-to-head randomized trials are limited. Average trial results don’t predict individual patient response.
- Side effect profiles are similar (primarily GI: nausea, vomiting, diarrhea, constipation), generally dose-dependent and most common during dose escalation.
- Contraindication profiles overlap significantly. Both carry a black box warning regarding personal or family history of medullary thyroid carcinoma or MEN2.
- The most important factor is which your prescribing clinician recommends based on your health history, goals, and current medication list.
Which GLP-1 medications compare best for weight management?
| Medication | Active ingredient | Dosing | Weight approval |
|---|---|---|---|
| Wegovy | Semaglutide 2.4 mg | Once weekly SC | Yes (BMI ≥30 or ≥27 + comorbidity) |
| Zepbound | Tirzepatide 2.5–15 mg | Once weekly SC | Yes (BMI ≥30 or ≥27 + comorbidity) |
| Saxenda | Liraglutide 3 mg | Once daily SC | Yes (adults + adolescents) |
| Compounded semaglutide | Semaglutide (API) | Once weekly SC | Rx required; 503A pharmacy; not FDA-approved product |
| Compounded tirzepatide | Tirzepatide (API) | Once weekly SC | Rx required; 503A pharmacy; not FDA-approved product |
SC = subcutaneous injection. Compounded formulations are available when branded products are on the FDA shortage list. Clinician evaluation required for all.
What is NOT a GLP-1 medication?
OTC supplements marketed as “GLP-1 support” (berberine, bitter melon, fiber blends) are not GLP-1 receptor agonists. They are dietary supplements in a separate regulatory category and should not appear on any list of GLP-1 medications. The naming is a marketing convention, not a pharmacological claim.
Frequently asked questions
What is the full list of GLP-1 medications available in the USA?
FDA-approved GLP-1 receptor agonists include: semaglutide (Ozempic, Wegovy, Rybelsus), tirzepatide (Mounjaro, Zepbound), liraglutide (Victoza, Saxenda), exenatide (Byetta, Bydureon), dulaglutide (Trulicity), and albiglutide (Tanzeum, discontinued). For weight management specifically, Wegovy (semaglutide), Zepbound (tirzepatide), and Saxenda (liraglutide) have weight-focused approvals. Compounded versions of semaglutide and tirzepatide are also available via licensed 503A pharmacies when the branded products are on the FDA shortage list.
What is the difference between semaglutide and tirzepatide?
Semaglutide is a GLP-1 receptor agonist only. Tirzepatide is a dual agonist that activates both GLP-1 and GIP (glucose-dependent insulinotropic polypeptide) receptors. Clinical trials (SURMOUNT vs STEP) suggest tirzepatide may produce modestly greater weight reduction on average, though individual response varies and both are clinically meaningful options.
Can I get compounded GLP-1 medication?
Compounded semaglutide and tirzepatide are available through licensed 503A compounding pharmacies when the branded products are on the FDA shortage list. This requires a valid prescription from a licensed clinician. Compounded versions are not FDA-approved as finished drug products but use pharmaceutical-grade API.
Are all GLP-1 medications injections?
Most GLP-1 medications are subcutaneous injections. The exception is Rybelsus (oral semaglutide tablets), which is FDA-approved for type 2 diabetes management. Compounded GLP-1 preparations (semaglutide, tirzepatide) are injectable.
Which GLP-1 medications are approved for weight management vs diabetes?
Weight management (BMI-based): Wegovy (semaglutide 2.4 mg weekly), Zepbound (tirzepatide), Saxenda (liraglutide 3 mg daily). Primarily diabetes: Ozempic (semaglutide 0.5–2 mg weekly), Mounjaro (tirzepatide), Victoza (liraglutide 1.2–1.8 mg), Trulicity (dulaglutide), Byetta/Bydureon (exenatide), Rybelsus (oral semaglutide). Some diabetes-approved GLP-1s are prescribed off-label for weight management.