Semaglutide
Quick Definition
Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist FDA-approved for type 2 diabetes (Ozempic, Rybelsus) and chronic weight management (Wegovy). It is administered as a once-weekly subcutaneous injection or as a daily oral tablet, and acts by slowing gastric emptying, increasing satiety signaling, and improving glucose-dependent insulin secretion.
In Depth
Semaglutide was first FDA-approved in 2017 for type 2 diabetes under the brand name Ozempic. The same molecule received approval at higher doses in 2021 for chronic weight management as Wegovy. The oral tablet form, Rybelsus, was approved for type 2 diabetes in 2019.
The molecule binds to and activates the GLP-1 receptor — a receptor normally activated by the body's own GLP-1 hormone after meals. Activation slows gastric emptying (food stays in the stomach longer, producing prolonged fullness), enhances glucose-dependent insulin release (raising insulin only when blood glucose is elevated), and modulates appetite signaling at the hypothalamus.
Semaglutide is engineered for an extended half-life through structural modifications to the native GLP-1 backbone, including a fatty acid chain that allows reversible albumin binding. The result is a half-life of approximately 7 days, supporting once-weekly subcutaneous dosing.
The pivotal weight loss evidence comes from the STEP trial program, which demonstrated approximately 15% mean body weight reduction over 68 weeks in adults with obesity. The diabetes evidence comes from the SUSTAIN trials, which showed both glycemic control and cardiovascular benefit in patients with type 2 diabetes.
Common side effects are concentrated during the dose-titration period and include nausea, diarrhea, vomiting, and constipation. Rare but serious risks include pancreatitis, gallbladder disease, and a labeled warning regarding rodent thyroid C-cell tumors (with contraindication in personal or family history of medullary thyroid carcinoma or MEN2).
Semaglutide is also available through 503A compounding pharmacies in some clinical contexts. The compounded preparations use the same active molecule but are not FDA-approved as finished drug products. The regulatory landscape for compounded semaglutide changed substantially in 2025 following the FDA's resolution of the semaglutide shortage.
Related Terms
Tirzepatide
Tirzepatide is a dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist administered by weekly subcutaneous injection. The FDA approved tirzepatide for type 2 diabetes management in 2022 under the brand name Mounjaro, and for chronic weight management in adults with obesity or overweight with weight-related comorbidities in 2023 under the brand name Zepbound. Compounded tirzepatide formulations, which are prepared by state-licensed compounding pharmacies pursuant to valid prescriptions, are not FDA-approved drug products and differ from the branded versions in formulation, dosing, and regulatory oversight.
Liraglutide
Liraglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist administered once daily via subcutaneous injection. The FDA approved liraglutide under the brand name Victoza for type 2 diabetes management and under the brand name Saxenda for chronic weight management in adults with obesity or overweight with at least one weight-related comorbidity. It mimics the action of naturally occurring GLP-1, a hormone that regulates blood sugar and appetite by slowing gastric emptying, enhancing insulin secretion, and reducing glucagon release. Compounded liraglutide formulations, which may be available through telehealth pharmacies like ZYNDIO, are not FDA-approved drug products and are prepared by state-licensed compounding pharmacies pursuant to a valid prescription from a licensed provider.
Compounded Medication
A compounded medication is one prepared by a licensed pharmacist for a specific patient, typically because the commercially manufactured product is unavailable, the patient cannot tolerate an inactive ingredient, or a non-standard dose is clinically required. Compounded preparations are not FDA-approved as finished drug products.
GLP-1 Receptor Agonist
A GLP-1 receptor agonist is a medication that activates the glucagon-like peptide-1 receptor, mimicking the body's GLP-1 hormone. The class is FDA-approved for type 2 diabetes and chronic weight management, and includes semaglutide, liraglutide, dulaglutide, and exenatide.