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Peptide drug (FDA approved, brands discontinued)Human trialsFDA approved

Exenatide

Exenatide

Last reviewed October 27, 2026 · 17 sources · Written for general readers · Compare with another compound →

The bottom line

Exenatide was the first GLP-1 drug, approved in 2005 for type 2 diabetes. It lowers blood sugar but causes only modest weight loss, and large trials found no clear heart benefit and no effect on Parkinson's disease. The brand products are discontinued in the US, and it was never approved for weight loss.

Where the evidence stands

What it is

Exenatide is a lab made peptide 39 amino acids long. It was first identified in a lizard, Heloderma suspectum, better known as the Gila monster. The end of its chain is capped as an amide, and its formula is C184H282N50O60S.[1] FDA's substance registry lists its CAS number as 141758-74-9.[2]

Byetta is the original short acting form, approved for blood sugar control in adults with type 2 diabetes.[1] Bydureon BCise is a long acting weekly form approved for adults and children 10 and older with type 2 diabetes.[3] Neither is approved for weight loss.[1][3]

AstraZeneca stopped selling the original Bydureon in 2021 and told FDA in August 2024 that it planned to permanently stop selling Byetta and Bydureon BCise.[4] A generic version of Byetta, approved in November 2024, is listed by FDA as a prescription product.[5]

Name
Exenatide (Exenatide)
Other names
Byetta, Bydureon, Bydureon BCise, generic exenatide
Type
Peptide drug (FDA approved, brands discontinued)
Sequence
HGEGTFTSDLSKQMEEEAVRLFIEWLKNGGPSSGAPPPS
CAS number
141758-74-9
Formula
C184H282N50O60S
Molecular weight
About 4186.6 g/mol

What it does in the body

Exenatide is a lab made copy of a 39 amino acid peptide first found in a lizard called the Gila monster. Its chain partly overlaps human GLP-1, and it switches on the same GLP-1 receptor.[1] The short acting form has a half life of about 2.4 hours, so it is given twice a day, while the weekly form releases it slowly from tiny beads.[1][3]

This is the biology, area by area. A change measured in the body, like a higher blood level, does not always mean a person feels a benefit. The claims check below covers that.

Blood sugar

Well established

In people with type 2 diabetes, it restored the quick first burst of insulin release after a sugar rise, which is usually lost in this disease. It also lowers glucagon, a hormone that pushes sugar up, when blood sugar is high.[1]

Gut

Well established

It slows how fast food leaves the stomach, so sugar from a meal enters the blood more slowly.[1] Nausea is the price: 40% to 44% had nausea in most Byetta trials versus 8% to 18% on placebo.[1]

Fat and appetite

Measured in people

The label says it reduces food intake in both animals and humans.[1] In 152 adults with obesity but no diabetes, weight fell 5.1 kg versus 1.6 kg on placebo over 24 weeks.[6] In 42 young people with obesity caused by brain tumor damage, BMI did not change more than placebo, but body fat fell about 3.1 kg more and waist size 3.5 cm more.[7]

Brain and nerves

Measured in people

In 16 women with idiopathic intracranial hypertension (high fluid pressure around the brain), pressure measured by an implanted sensor fell within 2.5 hours of a shot and stayed lower at 24 hours and 12 weeks.[8] But controlled trials in Parkinson's disease and in mild memory loss found no benefit.[9][10]

Heart and blood vessels

Measured in people

In EXSCEL, 14,752 adults with type 2 diabetes had heart attack, stroke or heart death in 11.4% on the weekly form versus 12.2% on placebo over a median of 38.7 months, which showed safety but not a clear benefit.[3]

Immune system

Measured in people

Because it is not a human peptide, many people make antibodies to it. About 32% of adults on the weekly form made high levels, which weakened its effect on blood sugar.[3] With the twice daily form, antibodies were linked to a weaker response in about 1% to 4%.[1]

How it works

Exenatide switches on the GLP-1 receptor, the target of the body's own GLP-1 hormone.[1]

  • It boosts insulin release when blood sugar is high and lowers glucagon, a hormone that raises blood sugar, when it is too high.[1]
  • It slows how fast food leaves the stomach.[1]
  • The long acting form packs the drug into tiny beads called microspheres, made of a slowly dissolving polymer, so it is released over time.[3]

The receptor action is well established and described in the FDA labels.

What the research shows

We keep animal and human evidence apart. A result in animals is a reason to study something in people, not proof that it works in people.

Animal and lab studies

Rodent studies are behind the thyroid warning

  • In a two year rat study of the long acting form, thyroid C cell tumors, both benign and cancerous, increased at every dose tested.[3]
  • In a two year rat study of Byetta, benign thyroid C cell tumors rose in females at all doses, at exposures 5 to 130 times those in people.[1]
  • In a two year mouse study of Byetta, no tumors were seen even at exposures about 95 times those in people.[1]
  • In pregnant mice, exposures about 390 times those in people slowed fetal growth and caused bone changes, and newborn deaths rose at about 3 times human exposure.[1]
  • Exenatide reduced alcohol intake in rodents and monkeys, which led to the human alcohol trial.[13]

Limit: Whether the rat thyroid findings apply to people is unknown.[3]

Human studies

Well studied in type 2 diabetes; mostly null outside it

  • Byetta trials: adults with type 2 diabetes were treated for 16 to 30 weeks, alone or with other diabetes drugs. HbA1c fell 0.5 to 1.0 point more than on placebo, and weight fell 1.1 to 2.9 kg, versus anything from a 1.0 kg gain to a 1.5 kg loss on placebo.[1]
  • Weekly form: in 26 to 28 week trials, HbA1c fell about 1.1 to 1.6 points and weight 1.4 to 2.7 kg. It lowered HbA1c a bit less than liraglutide (1.3 versus 1.5 points) and led to less weight loss (2.7 versus 3.6 kg).[3]
  • EXSCEL: 14,752 adults with type 2 diabetes got the weekly form or placebo for a median of 38.7 months. Major heart events were 11.4% versus 12.2%, which showed safety but not a clear benefit.[3]
  • Obesity without diabetes: 152 adults got twice daily shots or placebo with lifestyle advice for 24 weeks. Weight fell 5.1 kg versus 1.6 kg, and prediabetes returned to normal in 77% versus 56%.[6]
  • Young people with obesity: in 44 teens given the weekly form or placebo plus lifestyle help for 6 months, weight fell about 3 kg more and waist size 3.2 cm more, while liver fat did not change significantly.[11] In 42 people aged 10 to 25 with obesity after brain tumor treatment, 36 weeks of the weekly form did not lower BMI significantly more than placebo, but fat mass fell about 3.1 kg more.[7]
  • Parkinson's disease: a 2017 trial of 62 people found movement scores 3.5 points better than placebo after 48 weeks of weekly shots plus a 12 week break.[12] A larger 2025 phase 3 trial of 194 people treated for 96 weeks found no slowing of the disease, and serious side effects were similar (9% versus 11%).[9]
  • Alcohol use disorder: 127 people got weekly shots or placebo with talk therapy for 26 weeks. Heavy drinking days did not fall more than with placebo.[13]
  • Children 10 to 17 with type 2 diabetes: in a 24 week trial of 82 youths, HbA1c fell 0.25 points on the weekly form and rose 0.45 on placebo. About 64% developed high levels of antibodies to the drug.[3]
  • High pressure in the skull: 16 women with idiopathic intracranial hypertension got exenatide or placebo for 12 weeks while an implanted sensor tracked pressure. Pressure fell more on exenatide, with no serious safety signals.[8]
  • Mild memory loss: 32 adults got the weekly form or no treatment for 32 weeks. Memory scores did not improve, and women on exenatide scored worse.[10]

Limit: Nearly all large trials were in type 2 diabetes. Trials for Parkinson's disease, memory and alcohol did not show a clear benefit, and the skull pressure trial was tiny.

Claims check

The most common claims about this compound, and what studies actually found. Verdicts rate the evidence, not whether you should use it.

Lowers blood sugar

Shown in people

In placebo controlled Byetta trials of 16 to 30 weeks in adults with type 2 diabetes, HbA1c (a three month blood sugar average) fell about 0.5 to 1.0 point more than with placebo.[1] The weekly form lowered HbA1c by about 1.1 to 1.6 points in trials of 26 to 28 weeks.[3]

Causes weight loss

Mixed results

In diabetes trials, people on Byetta lost about 1.1 to 2.9 kg, usually 0.3 to 2.7 kg more than on placebo.[1] In a 24 week trial of 152 adults with obesity but no diabetes, exenatide plus lifestyle advice led to 5.1 kg loss versus 1.6 kg on placebo, a difference of about 3% of body weight.[6] In 44 teens with obesity, the weekly form led to about 3 kg more weight loss than placebo over 6 months.[11]

Protects the heart

No benefit in trials so far

EXSCEL followed 14,752 adults with type 2 diabetes for a median of 38.7 months. Heart attack, stroke or heart death happened in 11.4% on the weekly form versus 12.2% on placebo, a difference too small to rule out chance. It showed the drug did not raise heart risk.[3]

Slows Parkinson's disease

No benefit in trials so far

A 2017 trial of 62 people with Parkinson's disease found movement scores 3.5 points better than placebo after 60 weeks.[12] But a larger 2025 phase 3 trial of 194 people treated for 96 weeks found no difference: movement scores worsened 5.7 points on exenatide and 4.5 on placebo.[9]

Cuts alcohol cravings and drinking

Mixed results

In a 26 week trial of 127 people with alcohol use disorder, weekly exenatide did not reduce heavy drinking days overall versus placebo. Brain scans showed less reaction to alcohol cues, and in an unplanned look at people with obesity, drinking did fall.[13]

Lowers pressure inside the skull

Mixed results

In a placebo controlled trial of 16 women with idiopathic intracranial hypertension, pressure measured by an implanted sensor fell more on exenatide at 2.5 hours and 24 hours, with a smaller, borderline difference at 12 weeks. No serious safety problems were seen.[8] The trial was very small, and a larger trial is needed.

Protects memory

No benefit in trials so far

In a 32 week trial of 32 people with mild memory and thinking problems, weekly exenatide did not improve the main memory score versus no treatment, and women on it did worse. Blood sugar and weight did fall.[10] The trial was small, so a modest benefit cannot be ruled out.

Known risks and side effects

  • Nausea and stomach upset. In most Byetta trials, 40% to 44% had nausea versus 8% to 18% on placebo, vomiting affected 13% to 18%, and diarrhea up to 18%.[1] With the weekly form, nausea affected 8.2% and about 3.9% quit because of side effects.[3]
  • Low blood sugar with other diabetes drugs. When Byetta was added to a sulfonylurea, another diabetes pill, low blood sugar reached about 36% at the higher strength versus about 3% on placebo.[1]
  • Injection site lumps and antibodies. Lumps at the injection site were the most common side effect of the weekly form (10.5%), and rare serious reactions needed surgery. About 32% of adults made high levels of antibodies, which weakened blood sugar control.[3]
  • Pancreas, kidney, gallbladder and platelets. Both labels warn about pancreatitis (an inflamed pancreas), kidney injury from fluid loss, gallbladder disease, and a rare immune reaction that destroys platelets, the blood cells that help clotting.[1][3]
  • Boxed warning for thyroid tumors. The long acting form carries a boxed warning based on rat studies, and people with a personal or family history of medullary thyroid cancer or MEN 2 must not use it.[3]

Regulatory status

Today: Exenatide remains an FDA approved drug, but Drugs@FDA lists Byetta and Bydureon BCise as discontinued. A generic exenatide from Amneal is listed as a prescription product.[14][15][16][5] WADA's 2026 Prohibited List does not name GLP-1 drugs.[17]

  1. FDA approved Byetta, the first exenatide product.[15]
  2. FDA approved Bydureon BCise, a weekly long acting form.[16]
  3. AstraZeneca permanently stopped selling all strengths of the original Bydureon.[4]
  4. AstraZeneca told FDA it planned to permanently stop marketing Byetta and Bydureon BCise.[4]
  5. FDA approved a generic exenatide pen from Amneal.[14]

Sources

  1. AstraZeneca. BYETTA (exenatide) injection: prescribing information. Revised 09/2025. FDA label
  2. U.S. Food and Drug Administration, Global Substance Registration System. Exenatide (UNII 9P1872D4OL): codes. FDA GSRS
  3. AstraZeneca. BYDUREON BCISE (exenatide extended-release) injectable suspension: prescribing information. Revised 05/2025. FDA label
  4. U.S. Food and Drug Administration, Office of Surveillance and Epidemiology. Pediatric Postmarketing Pharmacovigilance Review: exenatide (Bydureon BCise, Bydureon, Byetta). April 14, 2025. FDA review
  5. U.S. Food and Drug Administration. Drugs@FDA: ANDA 206697, exenatide synthetic injection (Amneal). Drugs@FDA
  6. Rosenstock J, Klaff LJ, Schwartz S, et al. Effects of Exenatide and Lifestyle Modification on Body Weight and Glucose Tolerance in Obese Subjects With and Without Pre-Diabetes. Diabetes Care. 2010. PMID 20332357
  7. Roth CL, Perez FA, Whitlock KB, et al. A phase 3 randomized clinical trial using a once-weekly glucagon-like peptide-1 receptor agonist in adolescents and young adults with hypothalamic obesity. Diabetes Obes Metab. 2021;23(2):363-373. PMID 33026160
  8. Mitchell JL, Lyons HS, Walker JK, et al. The effect of GLP-1RA exenatide on idiopathic intracranial hypertension: a randomized clinical trial. Brain. 2023;146(5):1821-1830. PMID 36907221
  9. Vijiaratnam N, Girges C, Auld G, et al. Exenatide once a week versus placebo as a potential disease-modifying treatment for people with Parkinson's disease in the UK: a phase 3, multicentre, double-blind, parallel-group, randomised, placebo-controlled trial. Lancet. 2025. PMID 39919773
  10. Dei Cas A, Micheli MM, Aldigeri R, et al. Long-acting exenatide does not prevent cognitive decline in mild cognitive impairment: a proof-of-concept clinical trial. J Endocrinol Invest. 2024;47(9):2339-2349. PMID 38565814
  11. Weghuber D, Forslund AH, Ahlstrom HK, et al. A 6-month randomized, double-blind, placebo-controlled trial of weekly exenatide in adolescents with obesity. Pediatr Obes. 2020;15(7):e12624. PMID 32062862
  12. Athauda D, Maclagan K, Skene SS, et al. Exenatide once weekly versus placebo in Parkinson's disease: a randomised, double-blind, placebo-controlled trial. Lancet. 2017. PMID 28781108
  13. Klausen MK, Jensen ME, Moller M, et al. Exenatide once weekly for alcohol use disorder investigated in a randomized, placebo-controlled clinical trial. JCI Insight. 2022. PMID 36066977
  14. U.S. Food and Drug Administration. 2024 First Generic Drug Approvals (ANDA 206697, exenatide injection, reference Byetta, approved 11/19/2024). FDA
  15. U.S. Food and Drug Administration. Drugs@FDA: NDA 021773, Byetta (exenatide synthetic). Drugs@FDA
  16. U.S. Food and Drug Administration. Drugs@FDA: NDA 209210, Bydureon BCise (exenatide synthetic). Drugs@FDA
  17. World Anti-Doping Agency. World Anti-Doping Code International Standard: Prohibited List 2026. September 2025. WADA Prohibited List 2026
Medical disclaimer

This page is educational information only. It is not medical advice and does not replace care from a licensed medical provider. Do not use this page to decide whether to take any substance. Talk to a licensed medical provider first.

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