Exenatide
More actions
Exenatide is a synthetic version of exendin-4, originally isolated by John Eng at the Bronx VA Medical Center in 1992 from the saliva of the Gila monster (Heloderma suspectum).[3] The peptide is only 53% homologous to native human GLP-1 but is naturally resistant to DPP-4, that natural resistance is what made it the first clinically usable incretin mimetic, validating the GLP-1 receptor as a therapeutic target and opening the path to all subsequent agents in the class.
In contrast to the long-acting weekly agents that followed, exenatide carries a heavier GI side-effect burden (especially Byetta BID) and is associated with anti-exenatide antibody formation in a substantial minority of users, antibodies that can reduce efficacy.[1] Twice-daily Byetta was discontinued in the United States in 2024.[citation needed] Bydureon BCise remains available but is no longer commonly prescribed first-line.Experience
Log in to add your own experience.
Problems
Titration strategies
Steady-state plasma exenatide is reached only after 6–7 weeks of dosing, counsel patients that the medicine will keep ramping up well after the first injection. HbA1c response should be assessed at 12+ weeks, not earlier.[2]
Renal dosing: avoid if CrCl <45 mL/min.[2]Effects
- Nausea, historically the highest of any GLP-1 RA. ~40–50% of Byetta BID users report nausea; ~20% with Bydureon weekly.[1][2]
- Vomiting, diarrhea, constipation, dyspepsia[1]
- Injection-site reactions, notably higher with Bydureon (small nodules at injection sites are common, often visible/palpable for weeks)[2]
- Anti-exenatide antibodies, form in ~40% of users; high titers correlate with reduced glycemic efficacy[1]
- Headache, jitteriness (less common)[citation needed]
Pharmacokinetics
Chemistry. Exendin-4, a 39-amino-acid peptide originally isolated from the saliva of the Gila monster (Heloderma suspectum). Only 53% homologous with human GLP-1 but naturally resistant to DPP-4 cleavage because of a glycine at position 2.[3]
Byetta (BID): rapid absorption, peak ~2.1 h, half-life ~2.4 h. Renal elimination predominates (unlike most other GLP-1 RAs); dose adjustment required for CrCl 30–50, contraindicated <30.[1]
Bydureon BCise (weekly): exenatide is encapsulated in slow-release biodegradable polymer microspheres; multiple peaks occur as successive microsphere cohorts release the peptide. Steady-state plasma levels are reached only after 6–7 weeks of weekly dosing, meaning early efficacy looks weaker than other weekly GLP-1 RAs.[2]Pharmacodynamics
Receptor pharmacology. Selective agonist of the GLP-1 receptor. Mechanism identical to other GLP-1 RAs (glucose-dependent insulin secretion, glucagon suppression, delayed gastric emptying, hypothalamic appetite suppression).[4]
At maintenance doses:
- HbA1c reduction of ~0.8–1.0 percentage points (Byetta 10 µg BID or Bydureon 2 mg/wk)[1][2]
- Weight loss of ~2–3 kg[1]
- Cardiovascular outcomes: non-inferior but not superior to placebo in T2DM (EXSCEL), the only major GLP-1 RA CVOT not to demonstrate superiority[5]
Interactions
Pregnancy and lactation
Monitoring
- Baseline: HbA1c, weight, BP, renal function (especially important for exenatide, renally cleared)[1]
- Personal or family history of MTC or MEN2, contraindicated, do not start (Bydureon only, Byetta's label predates the class boxed warning conversion)[2]
- Every 3 months for first year: HbA1c, weight, GI tolerability, renal function, signs of pancreatitis or gallbladder disease
- Pre-procedure: Byetta, skip the dose before the procedure; Bydureon, hold weekly dose ≥7 days pre-op[6]
Patient counseling
- Byetta: inject within 60 min before a meal (not after). Skip the dose if you skip the meal.[1]
- Bydureon: same day each week. Suspension must be activated by vigorous shaking until uniformly cloudy, administration immediately after mixing is required.[2]
- Expect small injection-site nodules with Bydureon, these are the polymer microspheres and usually resolve over weeks to months.[2]
- GI side effects with Byetta BID peak in the first 8 weeks and often improve.[1]
- Surgery: hold Bydureon ≥7 days pre-op; for Byetta, skip the pre-procedure dose.[6]
Relevant anecdote
0
Relevant Literature
No literature entries yet.
Log in to submit relevant literature.
See also
References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 US FDA. Byetta (exenatide) prescribing information. AstraZeneca. https://www.accessdata.fda.gov/drugsatfda_docs/label/2009/021773s9s11s18s22s25lbl.pdf
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 US FDA. Bydureon BCise (exenatide extended-release) prescribing information. AstraZeneca. https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/209210s000lbl.pdf
- ↑ 3.0 3.1 Eng J, Kleinman WA, Singh L et al. (1992). Isolation and characterization of exendin-4, an exendin-3 analogue, from Heloderma suspectum venom. J Biol Chem 267(11):7402–5.
- ↑ Drucker DJ (2022). GLP-1 physiology informs the pharmacotherapy of obesity. Mol Metab 57:101351.
- ↑ Holman RR, Bethel MA, Mentz RJ et al. (2017). Effects of once-weekly exenatide on cardiovascular outcomes in type 2 diabetes (EXSCEL). NEJM 377(13):1228–39. doi:10.1056/NEJMoa1612917
- ↑ 6.0 6.1 Kindel TL et al. (2024). Perioperative GLP-1 receptor agonist safety guidance. Surg Obes Relat Dis 20(12):1183–8.