Exenatide

A synthetic 39-amino-acid copy of exendin-4, a Gila monster venom peptide, and the first GLP-1 receptor agonist approved in the United States (2005); every branded product has since been discontinued, leaving a generic twice-daily pen for type 2 diabetes.

Also referenced as: Exendin-4, Byetta, Bydureon, Bydureon BCise, AC2993, AC-2993, exenatide synthetic, exenatide extended-release, ITCA 650

Also appears in: Weight loss

COA Public product evidence No certificate records are bound to a tracked Exenatide product page A record counts here only when a vendor publishes a certificate against one of its own tracked Exenatide product pages. Other certificates naming this compound may still exist — search the wider certificate database. →

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What is Exenatide?

Exenatide is a genuine peptide: a synthetic 39-residue amide whose sequence is identical to exendin-4, a peptide first purified from the venom of the Gila monster, Heloderma suspectum. It shares roughly half of its sequence with human GLP-1, but it binds and activates the GLP-1 receptor with full potency and, because it carries glycine rather than alanine at position 2, it is not cleaved by dipeptidyl peptidase-4 the way native GLP-1 is — so the lizard peptide lasts hours in human circulation where the human hormone lasts minutes.

That accident of venom chemistry made exenatide the first GLP-1 receptor agonist to reach the market anywhere, approved in the United States on April 28, 2005 as twice-daily Byetta, followed by once-weekly microsphere formulations (Bydureon, 2012; Bydureon BCise, 2017). It appears in research-peptide catalogs today for the opposite reason: the class it founded moved on to semaglutide and tirzepatide, its originator has discontinued every branded presentation, and the molecule now circulates as bulk material, often listed under its original name, exendin-4.

How it works

• A venom peptide that happens to be a full GLP-1 receptor agonist. Exendin-4 was isolated from Heloderma suspectum venom as a 39-amino-acid peptide differing from exendin-3 at only two positions (Eng et al., Journal of Biological Chemistry, 1992;267(11):7402–7405). The following year it was shown to be a high-potency agonist at the GLP-1 receptor of insulin-secreting beta cells, while its N-terminally truncated fragment exendin-(9-39) acts as an antagonist (Göke et al., Journal of Biological Chemistry, 1993;268(26):19650–19655), a finding reproduced on the cloned human islet GLP-1 receptor (Thorens et al., Diabetes, 1993;42(11):1678–1682).
• Glucose-dependent insulin release, glucagon suppression, and slowed gastric emptying. Approved labeling describes exenatide as enhancing glucose-dependent insulin secretion from the pancreatic beta cell, suppressing inappropriately elevated glucagon secretion, and slowing gastric emptying. In the first controlled human studies, synthetic exendin-4 significantly reduced both postprandial and fasting plasma glucose in people with type 2 diabetes (Kolterman et al., Journal of Clinical Endocrinology and Metabolism, 2003;88(7):3082–3089). Because the insulinotropic effect is conditional on elevated glucose, exenatide alone carries a low intrinsic hypoglycemia risk; the labeled risk arises when it is combined with insulin or a sulfonylurea.
• DPP-4 resistance without albumin binding. Unlike liraglutide and semaglutide, which gain their half-lives from fatty-acid chains that bind albumin, exenatide’s durability comes from its backbone alone. The Byetta label gives a mean terminal half-life of 2.4 hours after subcutaneous injection, with clearance predominantly by glomerular filtration — long enough for twice-daily dosing, but short enough that a week-long product required encapsulating the peptide in biodegradable polymer microspheres rather than changing the molecule.

Research status

Type 2 diabetes, twice-daily. The pivotal 30-week placebo-controlled trials (the AMIGO program) tested exenatide 5 and 10 mcg twice daily on top of existing oral therapy. In sulfonylurea-treated patients, HbA1c fell by 0.86 percentage points at the 10 mcg dose versus a 0.12-point rise on placebo, with modest weight loss and dose-dependent nausea as the leading adverse event (Buse et al., Diabetes Care, 2004;27(11):2628–2635); the metformin-background trial produced a similar glycemic effect and about 2.8 kg of weight loss at 10 mcg (DeFronzo et al., Diabetes Care, 2005;28(5):1092–1100). These trials supported the April 2005 approval of Byetta (NDA 021773) as an adjunct to diet and exercise in adults with type 2 diabetes. A later randomized, placebo-controlled study in 120 patients aged 10 to 17 did not demonstrate effectiveness, and the Byetta label was updated in November 2021 to say so.

Type 2 diabetes, once-weekly. DURATION-1 compared 2 mg of exenatide in poly(lactide-co-glycolide) microspheres injected once weekly against 10 mcg twice daily over 30 weeks: HbA1c fell 1.9 versus 1.5 percentage points, meeting non-inferiority and then superiority, with less nausea in the weekly arm (Drucker et al., Lancet, 2008;372(9645):1240–1250). FDA issued two complete response letters in 2010 — the second asking for a thorough QT study — before approving Bydureon on January 27, 2012 (NDA 022200), first as a single-dose vial-and-diluent tray and, from 2014, as a dual-chamber pen. Bydureon BCise, a pre-mixed autoinjector of the same microspheres, was approved on October 20, 2017 (NDA 209210). On July 22, 2021, FDA extended the extended-release indication to patients aged 10 and older on the strength of an 82-patient pediatric trial — the first once-weekly GLP-1 receptor agonist labeled for adolescents.

Cardiovascular outcomes: neutral. EXSCEL (NCT01144338) randomized 14,752 patients with type 2 diabetes to once-weekly exenatide 2 mg or placebo across 687 sites, following them for a median of 3.2 years. The primary composite of cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke occurred in 11.4% of the exenatide group and 12.2% of the placebo group (hazard ratio 0.91; 95% CI 0.83–1.00). Exenatide met non-inferiority for safety (P<0.001) but missed superiority for efficacy (P=0.06) (Holman et al., New England Journal of Medicine, 2017;377(13):1228–1239). It therefore sits between the GLP-1 receptor agonists that demonstrated cardiovascular benefit (liraglutide, semaglutide, dulaglutide) and those that did not; no cardiovascular-risk-reduction indication was ever added to any exenatide label.

Parkinson’s disease: Phase 3 failure. A single-center 60-week Phase 2 trial (NCT01971242) in 62 randomized patients reported that once-weekly exenatide produced a 3.5-point advantage on the off-medication MDS-UPDRS part 3 score at 60 weeks, 12 weeks after the last dose (Athauda et al., Lancet, 2017;390(10103):1664–1675), which drove a decade of interest in GLP-1 agonists as disease-modifying agents. The confirmatory Exenatide-PD3 trial (NCT04232969), 194 participants at six UK sites over 96 weeks, did not replicate it: the primary endpoint was not met (p=0.47), off-medication MDS-UPDRS part 3 scores worsened in both arms (by 5.7 points on exenatide versus 4.5 on placebo), and secondary outcomes did not favor exenatide (Vijiaratnam et al., Lancet, 2025;405(10479):627–636). The authors found no evidence to support exenatide as a disease-modifying treatment for Parkinson’s disease. One caveat now attaches to that report: on June 22, 2026, The Lancet published an Expression of Concern after the corresponding author informed the journal of regulatory inspection findings at King’s College Hospital NHS Foundation Trust, one of the six trial sites, and asked the sponsor’s institution to investigate (Lancet, 2026;407(10548):2588). As of October 2026 the paper has not been corrected or retracted, and nothing in the notice points toward a hidden positive result — but the trial’s data integrity is formally under review.

Implantable exenatide: refused. ITCA 650 delivered continuous exenatide from a subdermal osmotic mini-pump intended to be replaced every six months. FDA issued complete response letters on September 21, 2017 and March 9, 2020; on September 21, 2023 the Endocrinologic and Metabolic Drugs Advisory Committee voted 19–0 that the benefits did not outweigh the risks, citing acute kidney injury and cardiovascular safety concerns, and on August 23, 2024 FDA published its final decision refusing to approve the application on the ground that Intarcia had not shown the product to be safe for its intended use.

Market exit. The original Bydureon single-dose tray was permanently discontinued in 2018 and the Bydureon Pen in March 2021, both for business reasons. AstraZeneca then discontinued Byetta on October 25, 2024 and Bydureon BCise on October 28, 2024 and notified FDA; all three NDAs are now listed as Discontinued in Drugs@FDA. The European Commission withdrew Byetta’s EU marketing authorization on January 1, 2026 at the holder’s request, for commercial reasons. Separately, FDA approved the first generic exenatide prefilled pen on November 21, 2024, and a generic 10 mcg pen launched in April 2025, so an approved exenatide product remains available in the United States even though no originator product does.

Common dosage forms

• Multi-dose prefilled pens at 250 mcg/mL, delivering 5 mcg per dose (300 mcg in 1.2 mL) or 10 mcg per dose (600 mcg in 2.4 mL), 60 doses per pen. This is the Byetta presentation and the one the current generic reproduces; it is the only exenatide format still marketed in the United States.
• Extended-release microsphere suspension, 2 mg per weekly dose, in three successive discontinued presentations: a vial of powder with a prefilled diluent syringe (Bydureon kit), a dual-chamber pen (Bydureon Pen), and a pre-mixed single-dose autoinjector (Bydureon BCise, 2 mg/0.85 mL).
• Implantable osmotic mini-pump (ITCA 650), a drug-device combination that was never approved and is not available.
• Lyophilized powder in vials, typically labeled in milligrams for reconstitution and frequently sold under the name “exendin-4” rather than exenatide, in research-market listings. This format has no counterpart in the approved product line, which has only ever consisted of solution pens and microsphere suspensions.
• Multi-compound blend vials pairing exenatide or exendin-4 with other metabolic peptides, where the per-vial exenatide content is often not stated separately.

Key considerations

• Approved and generically available, but orphaned by its originator. Exenatide carries full FDA approval for type 2 diabetes, and a generic prefilled pen is currently marketed; the FDA Approved status reflects that an FDA-approved drug product containing the molecule exists. At the same time, every AstraZeneca presentation — the Bydureon tray (2018) and pen (2021), then Byetta and Bydureon BCise (October 2024) — has been discontinued for business reasons rather than safety, and the EU authorization for Byetta was withdrawn on January 1, 2026. Readers who encounter “Byetta is discontinued” and “exenatide is FDA approved” are reading two true statements about different products. No extended-release exenatide product of any kind remains on the US market.
• Labeled safety signals. The twice-daily labeling carries no boxed warning but lists acute pancreatitis, hypoglycemia with concomitant insulin or insulin secretagogues, acute kidney injury due to volume depletion, severe gastrointestinal adverse reactions, immunogenicity, hypersensitivity, drug-induced thrombocytopenia, acute gallbladder disease, and pulmonary aspiration during general anesthesia or deep sedation among its warnings and precautions. The extended-release products carried the GLP-1 class boxed warning for thyroid C-cell tumors, which the short-acting product never did. Approved labeling also states that exenatide is not a substitute for insulin and should not be used in type 1 diabetes or diabetic ketoacidosis.
• Immunogenicity is a real, exenatide-specific limitation. Because the sequence is only about half human, anti-exenatide antibodies develop in a substantial share of treated patients, most at low titer; labeling reports that in a small percentage (roughly 1 to 4 percent across the pivotal studies) antibody formation was associated with an attenuated glycemic response. This is one reason the field moved toward human-sequence analogs, and it is a consideration that generic cross-reading from semaglutide or liraglutide data does not capture.
• The evidence record is deep but ends in neutral and negative results. Exenatide has one of the oldest trial records of any GLP-1 receptor agonist, yet its cardiovascular outcomes trial was neutral, its Parkinson’s disease Phase 3 failed in 2025 (and that report itself is now under an Expression of Concern), its implantable form was refused in 2024, and its weight effect in trials (roughly 1 to 3 kg) was never large enough to support an obesity indication. Claims of neuroprotective or weight-management benefit attributed to “exendin-4” in research-market copy rest on preclinical work and the small 2017 Phase 2 study, not on the larger trials that followed.
• Naming confusions. Exenatide and exendin-4 are the same 39-residue sequence; FDA records list the active ingredient as “exenatide synthetic.” Exendin-3 is a different venom peptide (two substitutions), exendin-(9-39) is a receptor antagonist rather than an agonist and is in development under the name avexitide, and lixisenatide is a distinct exendin-4-derived analog with a modified C-terminus. Byetta, Bydureon, and Bydureon BCise contain the same peptide at very different doses and release profiles and were never interchangeable; AC2993 is the molecule’s original development code and ITCA 650 the name of the unapproved implant.