What makes a medicine a GLP-1
GLP-1 (glucagon-like peptide-1) is released by the gut after a meal and acts on receptors that influence insulin, glucagon, stomach emptying and appetite. The body breaks the natural hormone down within minutes: the Saxenda® label gives it a half-life of 1.5 to 2 minutes [7].
A GLP-1 receptor agonist activates the same receptor but lasts far longer. Every label below calls its product a GLP-1 receptor agonist; tirzepatide is labelled as a GIP receptor and GLP-1 receptor agonist because it also acts on a second gut-hormone receptor [4][5]. The molecules are built very differently, which partly explains why some are taken twice a day and others once a week.
Every US brand in one table
Each row restates section 1 (approved use) and sections 2 and 3 (how it is taken and supplied) of that product’s US prescribing information, checked on 20 October 2026. Exenatide products are left out because their US approvals have been withdrawn; they are covered further down. The table explains the labels; it does not say which medicine suits anyone.
| Brand | Active ingredient | Form and schedule | US approved use (with diet and activity) | Source |
|---|---|---|---|---|
| Ozempic® injection | semaglutide | pen or prefilled syringe, once weekly | blood sugar in adults with type 2 diabetes; heart events with type 2 diabetes and heart disease; kidney decline with type 2 diabetes and chronic kidney disease | [1] §1–3 |
| Rybelsus® | semaglutide | tablet, once daily, empty stomach | blood sugar in adults with type 2 diabetes; heart events in high-risk adults with type 2 diabetes | [3] §1–3 |
| Ozempic® tablets | semaglutide | tablet, once daily, empty stomach | the same uses as Rybelsus®; not interchangeable milligram for milligram | [3] §1–3 |
| Wegovy® injection | semaglutide | single-dose pen or syringe, or multi-dose FlexTouch® pen, once weekly | heart events in adults with heart disease and obesity or overweight; weight reduction and maintenance in adults and from age 12; MASH with moderate to advanced fibrosis | [2] §1–3 |
| Wegovy® tablets | semaglutide | tablet, once daily, empty stomach | heart events as for the injection; weight reduction and maintenance in adults | [2] §1–3 |
| Mounjaro® | tirzepatide | single-dose pen or vial, multi-dose vial or KwikPen®, once weekly | blood sugar in adults and children 10+ with type 2 diabetes; heart events in high-risk adults with type 2 diabetes | [4] §1–3 |
| Zepbound® | tirzepatide | single-dose pen or vial, multi-dose vial or KwikPen®, once weekly | weight reduction and maintenance in adults; obstructive sleep apnea (moderate to severe) in adults who have obesity | [5] §1–3 |
| Victoza® | liraglutide | prefilled pen, once daily | blood sugar in adults and children 10+ with type 2 diabetes; heart events with type 2 diabetes and heart disease | [6] §1–3 |
| Saxenda® | liraglutide | prefilled pen, once daily | weight reduction and maintenance in adults and in those 12+ weighing over 60 kg with obesity | [7] §1–3 |
| Trulicity® | dulaglutide | single-dose pen, once weekly | blood sugar in adults and children 10+ with type 2 diabetes; heart events with heart disease or several risk factors | [8] §1–3 |
| Foundayo™ | orforglipron | tablet, once daily, with or without food | weight reduction and maintenance in adults | [9] §1–3 |
Semaglutide: one molecule, four product lines
- Ozempic® injection is the weekly diabetes product. It comes in multi-dose pens and, in the current label, also in single-dose prefilled syringes [1].
- Rybelsus® and Ozempic® tablets share one label. Rybelsus® uses 3, 7 and 14 mg tablets and Ozempic® tablets 1.5, 4 and 9 mg; the label says the two cannot be swapped milligram for milligram [3].
- Wegovy® injection now has three presentations: single-dose pens, including a 7.2 mg strength called Wegovy® HD, single-dose syringes, and a multi-dose FlexTouch® pen that gives four 2.4 mg doses. Wegovy® tablets come as 1.5, 4, 9 and 25 mg [2].
- The tablets are swallowed first thing in the morning, before eating, with a small amount of plain water (the labels set a 4-ounce limit), and food, drink or other tablets wait at least 30 minutes [2][3].
- Semaglutide has a half-life of about one week, and the Wegovy® label advises against combining it with any other semaglutide product or GLP-1 receptor agonist [1][2].
Tirzepatide: Mounjaro® and Zepbound®
Mounjaro® is the diabetes brand and Zepbound® the weight and sleep apnea brand. Both are supplied as single-dose pens and vials and as multi-dose vials or KwikPen® pens that hold four doses [4][5]. The Mounjaro® label added children aged 10 and older in December 2025 and a heart-events indication in August 2026; the latter rests on SURPASS-CVOT, in which tirzepatide was compared with dulaglutide rather than placebo and was found non-inferior, with a hazard ratio of 0.92 [4].
Tirzepatide’s half-life is about 5 days in the Mounjaro® label and 5 to 6 days in people with obesity in the Zepbound® label. The Zepbound® label advises against combining it with other tirzepatide products or any GLP-1 receptor agonist [4][5].
Liraglutide and dulaglutide
Liraglutide is the daily option: Victoza® for type 2 diabetes and Saxenda® at a higher dose for weight. Its half-life is about 13 hours [6][7]. The NIDDK describes Victoza® as the same drug at a lower dose under a different name [16]. The Saxenda® label advises against combining it with other liraglutide products or any GLP-1 receptor agonist [7].
Dulaglutide, sold as Trulicity®, is built differently from the others: a fusion protein in which a GLP-1-like sequence is joined to part of an antibody, with a molecular weight of about 63 kilodaltons. Its half-life is about 5 days, and it comes in single-dose pens of 0.75, 1.5, 3 and 4.5 mg [8].
Exenatide: approved in 2005, withdrawn since
Exenatide was the earliest of these ingredients to be approved in the US, in 2005. Its last label described Byetta® as a twice-daily injection before the morning and evening meals for adults with type 2 diabetes, with an average terminal half-life of 2.4 hours; unlike the other products here, it carried no thyroid boxed warning [10].
Approval is no longer in place. A Federal Register notice records that FDA withdrew approval of Byetta® as of 3 September 2025 after AstraZeneca reported it was no longer marketed, and a March 2026 notice lists the weekly Bydureon® and Bydureon BCise® products with a withdrawal date of 8 April 2026 [11][19]. Stock already in pharmacies on those dates could be dispensed until it ran out or expired. In the EU, the Byetta® authorisation was withdrawn on 1 January 2026 [20]. If you used one of them, your prescriber can explain what replaced it in your care.
Orforglipron: Foundayo™
Foundayo™ is the newest ingredient, first approved in the US in 2026. It is a once-daily tablet that can be taken with or without food, and its US label covers weight reduction and long-term maintenance in adults [9].
It is not a peptide. The label gives orforglipron calcium a molecular weight of 902 g/mol, against 3,751 Da for liraglutide, 4,114 g/mol for semaglutide and 4,814 Da for tirzepatide [2][4][7][9]. Its half-life is about 29 to 49 hours, steady levels are reached after about a week, and it is broken down mainly by the liver enzyme CYP3A4, so some other medicines change the dose limit [9].
Same names, different documents abroad
- European Union: tirzepatide is authorised only as Mounjaro®, and its product information covers both type 2 diabetes (from age 10) and adult weight management [12]. EMA lists no Zepbound® product.
- European Union: the Rybelsus® tablets described there start at 1.5 mg and list maintenance doses of 4, 9, 25 and 50 mg, a different strength series from the US Rybelsus® label [3][13].
- European Union: EMA’s committee for human medicines adopted a positive opinion on Foundayo™ on 15 October 2026 for weight management and for adults with type 2 diabetes. EMA says the full product information will appear after the European Commission grants the authorisation [14].
- Canada: the Wegovy® monograph covers the injection, and its heart claim is narrower than the US one: reducing the risk of non-fatal heart attack in adults with established heart disease and a BMI of 27 or more [15].
What they have in common
- Every current product carries a boxed warning about thyroid C-cell tumours, and none is to be used by anyone whose own or family history includes medullary thyroid carcinoma, or who has MEN 2; the withdrawn Byetta® label had no such box [1][9][10].
- Most are started low and raised in steps, which the labels link to fewer stomach side effects; nausea, diarrhoea and vomiting are among the most common reactions in every label checked [1][5][8][9].
- Each label says the medicine slows stomach emptying, which can affect tablets taken at the same time; several ask for closer monitoring of oral medicines whose levels need tight control [2][4][8][9].
- Taking two GLP-1 products together is advised against in the Wegovy®, Zepbound®, Saxenda® and Foundayo™ labels [2][5][7][9].
Where they sit among weight medicines
GLP-1 medicines are not the only prescription option for weight. The NIDDK page on weight medicines, last reviewed in June 2024, lists six FDA-approved drugs for long-term use: orlistat, phentermine-topiramate, naltrexone-bupropion, liraglutide, semaglutide and tirzepatide. It predates Foundayo™. It says medicines do not replace healthy eating and activity, and that the choice is made with your health care professional [16].
Some names you may see online are not on any list here. The FDA says compounded drugs are not FDA approved and are not reviewed for safety, effectiveness or quality before they are sold, and that retatrutide and cagrilintide cannot be used in compounding under federal law and are not part of any FDA-approved drug [17].
Ozempic®, Wegovy®, Rybelsus®, Saxenda®, Victoza® and FlexTouch® are registered trademarks of Novo Nordisk A/S. Mounjaro®, Zepbound®, Trulicity® and KwikPen® are registered trademarks, and Foundayo™ is a trademark, of Eli Lilly and Company. Byetta® and Bydureon BCise® are trademarks of the AstraZeneca group of companies. PepLabo is not affiliated with or endorsed by Novo Nordisk, Eli Lilly and Company or AstraZeneca.
