What Is a GLP-1 Receptor Agonist? Plain Explanation
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GLP-1 receptor agonist

Also called GLP-1, GLP-1 RA, GLP-1 agonist, GLP-1 analog · Reviewed

Definition: A GLP-1 receptor agonist is a drug that switches on the same receptor as GLP-1 (glucagon-like peptide-1), a hormone the gut releases after you eat. GLP-1 raises insulin when blood sugar is high, lowers glucagon and reduces appetite. Semaglutide (Ozempic, Wegovy) and liraglutide are GLP-1 receptor agonists.

How it works

"Agonist" means a molecule that activates a receptor. Drug makers change the GLP-1 chain to make it last longer. The Wegovy label describes semaglutide as a GLP-1 analog with 94% sequence match to human GLP-1 and an elimination half-life of about 1 week, which is why it is a once-weekly shot.

GLP-1 is one of two "incretin" hormones, gut hormones that boost insulin after a meal. The other is GIP. GLP-1 also slows appetite, which over time leads to weight loss (Nauck & Meier 2018).

Why it matters when you track doses

GLP-1 medicines start low and step up, a process called titration. A log that records the dose and the date of each change makes it easy to line up how you feel with each step.

Reading the Wegovy step schedule

  1. The Wegovy label starts at 0.25 mg once weekly for weeks 1 to 4.
  2. Then 0.5 mg for weeks 5 to 8, 1 mg for weeks 9 to 12, and 1.7 mg for weeks 13 to 16.
  3. The usual maintenance dose of 2.4 mg begins at week 17. That is 4 steps of 4 weeks, or 16 weeks, before the maintenance dose.

Your prescriber may hold you on a step longer. Log the dose you actually took, not the one the schedule says.

Common mix-ups

  • Tirzepatide is not only a GLP-1 drug. It also activates the GIP receptor (Mounjaro label).
  • Compounded or "research" semaglutide is not Wegovy. FDA says compounded drugs are not FDA approved, and that salt forms such as semaglutide sodium are different active ingredients.

Read more on Dose Track: Semaglutide · Wegovy · Semaglutide vs tirzepatide · GLP-1 units guide

General education drawn from labels and published studies, not personal medical advice. Your prescriber, pharmacist and the label that came with your product are the final word.
GIP (glucose-dependent insulinotropic polypeptide)GIP (glucose-dependent insulinotropic polypeptide) is a hormone released by K cells in the upper gut after… Amylin analogAn amylin analog is a man-made version of amylin, a hormone your pancreas releases together with insulin… Titration (dose escalation)Titration means adjusting a dose in planned steps, usually starting low and going up, until a target or… Half-lifeHalf-life is the time it takes for the amount of a drug in your body to fall by half. After one half-life,… Compounding pharmacyA compounding pharmacy makes a medicine from raw ingredients for a specific patient, rather than…

Frequently asked questions

What does GLP-1 stand for?+
Glucagon-like peptide-1, a hormone released by the gut after eating.
Why is semaglutide taken once a week?+
The Wegovy label gives semaglutide an elimination half-life of about 1 week, so one shot keeps working for days.
Is tirzepatide a GLP-1 receptor agonist?+
Yes, and also a GIP receptor agonist. The Mounjaro label calls it a GIP receptor and GLP-1 receptor agonist.

Sources

  1. Wegovy (semaglutide) US prescribing information, DailyMed
  2. Nauck & Meier. Diabetes Obes Metab 2018 (incretin hormones GIP and GLP-1, review). PMID 29364588
  3. Mounjaro (tirzepatide) US prescribing information, DailyMed
  4. FDA: FDA's concerns with unapproved GLP-1 drugs used for weight loss

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