What it is
Exenatide is the peptide that started the GLP-1 drug class. It is 39 amino acids long, ends in an amide, and weighs 4,186.6 daltons. The Byetta label gives its full sequence and says it was originally identified in the Gila monster, Heloderma suspectum — a venomous lizard of the American south-west. The natural peptide is called exendin-4; exenatide is its synthetic copy.
That origin matters for how it behaves. Human GLP-1 is broken down quickly by the enzyme DPP-4. Exendin-4 is not the human hormone: its sequence only partially overlaps GLP-1, yet it still switches on the human GLP-1 receptor, and it lasts hours rather than minutes.
How it works
Per the Byetta label, exenatide raises insulin release from the pancreas when blood glucose is high, suppresses glucagon, and slows stomach emptying. The insulin effect fades as glucose falls towards normal, and the label notes that exenatide does not block the body's glucagon response to low blood sugar.
Its timing, from the label:
| Measure | Value |
|---|---|
| Time to peak after injection under the skin | 2.1 hours (median) |
| Terminal half-life | 2.4 hours |
| Measurable in blood | about 10 hours |
| Main route out | kidney filtration, then breakdown |
A half-life measured in hours is why Byetta was a twice-daily injection.
A class founder, now almost off the shelf
| Product | Form | Approved | Status in FDA data, 2026-09-27 |
|---|---|---|---|
| Byetta | 5 and 10 mcg pens, twice daily | 2005 | Discontinued |
| Bydureon | Extended-release weekly kit | 2012 | Discontinued |
| Bydureon Pen | Weekly pen | 2012 | Discontinued |
| Bydureon BCise | Weekly autoinjector | 2017 | Discontinued |
| Exenatide (Amneal generic) | 5 and 10 mcg pens | 2024-11-19 | Prescription |
So the first GLP-1 drug is now carried in the US by a single generic of its original twice-daily form. The weekly versions — the ones built to compete with dulaglutide and semaglutide — are all listed as discontinued.
Doses on the label
Reported as the Byetta label states them, not as guidance: 5 mcg twice daily, injected within the 60 minutes before the morning and evening meals (or two main meals at least six hours apart), increased to 10 mcg twice daily after one month. Each pen holds 60 doses — a month of twice-daily use. The label says it should not be given after a meal.
The heart trial
EXSCEL (NEJM 2017, NCT01144338) tested once-weekly exenatide 2 mg against placebo in 14,752 people with type 2 diabetes, 73% of whom already had heart disease, for a median 3.2 years. The composite of heart attack, stroke or cardiovascular death occurred in 11.4% on exenatide and 12.2% on placebo — hazard ratio 0.91 (0.83–1.00). That established safety, but not benefit: unlike liraglutide and dulaglutide, exenatide carries no cardiovascular indication.
Safety
The Byetta label's serious warnings: acute pancreatitis; never sharing a pen between patients; low blood sugar with insulin or insulin secretagogues; acute kidney injury from fluid loss; severe gastrointestinal reactions; immunogenicity (antibodies against a non-human sequence); hypersensitivity; drug-induced low platelets; gallbladder disease; and pulmonary aspiration during anaesthesia. Its label also shows it slows the absorption of other oral drugs — acetaminophen's peak level fell by up to 56% when given an hour after exenatide.
Where it stands
378 ClinicalTrials.gov records list exenatide as an intervention, and Europe PMC's MEDLINE index holds 2,722 records naming it in the title or abstract, 386 tagged as randomised controlled trials (2026-09-27). The research record is large; the commercial record is almost closed.
Related reading
Every later GLP-1 drug in this library started from the receptor exenatide proved: liraglutide, dulaglutide, semaglutide and the dual agonist tirzepatide. The amylin analogue pramlintide came from the same developer, Amylin Pharmaceuticals, and was approved six weeks earlier.