Exenatide
Also known as: Byetta, Bydureon, Bydureon BCise
One of the first GLP-1 receptor agonists, FDA-approved since 2005. Originally derived from Gila monster saliva. Available as twice-daily injections (Byetta) or once-weekly (Bydureon BCise). An older option that's been largely overtaken by semaglutide and tirzepatide.
How it works
Exenatide is a synthetic version of exendin-4, a peptide found in Gila monster venom that mimics human GLP-1. It stimulates insulin release when blood sugar is high, slows stomach emptying, and reduces glucagon secretion. The extended-release version (Bydureon BCise) uses microspheres to slowly release the drug over a week.
Common uses
- Type 2 diabetes management
- Blood sugar control alongside diet and exercise
- Modest weight loss as a secondary benefit
Side effects
- Nausea (36-44%, the most common, usually improves within 4-8 weeks)
- Vomiting (4-13%)
- Diarrhea (6-13%)
- Injection site reactions (especially with extended-release form)
- Headache
- Low blood sugar when combined with sulfonylureas or insulin
- Rare: pancreatitis, kidney injury
Key research
- Multiple Phase 3 trials demonstrated HbA1c reductions of 0.8-1.5% in type 2 diabetes
- Weight loss of 2-5 kg typical over 24-30 weeks (less than newer GLP-1 drugs)
- EXSCEL cardiovascular outcomes trial showed non-inferiority but not superiority vs placebo for cardiovascular events
Safety notes
- Boxed warning for thyroid C-cell tumors with extended-release form (Bydureon)
- Original Bydureon vial/pen was discontinued in 2021. Bydureon BCise autoinjector is still available
- Byetta (twice-daily) still marketed but less commonly prescribed
- Generally considered less effective for weight loss than newer GLP-1 options like semaglutide
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