DurgicalDurgical
EN
Open the app

Pharmacology · GLP-1 receptor agonists

Tirzepatide !

A weekly injection that activates both GIP and GLP-1 receptors: large falls in glucose and weight. Used in type 2 diabetes and obesity.

Updated 2026-11-01

  • Class: GLP-1 receptor agonists
  • Receptor: GIP receptor and GLP-1 receptor (dual agonist)
  • ATC code: A10BX16
  • WHO Model List of Essential Medicines

The figure shows tirzepatide bound to the human GIP receptor coupled to its Gs protein; tirzepatide also activates the GLP-1 receptor.

Target in 3D: GIP receptor and GLP-1 receptor (dual agonist). PDB structure 7FIY (RCSB PDB, public domain). View the structure at RCSB PDB

Mechanism of action

Tirzepatide is a single peptide built on the GIP sequence with a fatty diacid chain that binds albumin. It activates the GIP receptor and the GLP-1 receptor, both Gs-coupled. Together they increase glucose-dependent insulin release, lower glucagon, slow gastric emptying and reduce food intake, producing larger weight loss than GLP-1 agonism alone in trials.

  1. Activates GIP and GLP-1 receptors (Gs, cAMP)
  2. More insulin when glucose is high, less glucagon
  3. Stomach empties slowly; appetite and intake fall
  4. Large falls in HbA1c and body weight

Pharmacokinetics

Absorption
Weekly subcutaneous injection.
Distribution
Highly bound to albumin.
Metabolism
Broken down by peptidases and fatty-acid oxidation.
Half-life
Long, which allows once-weekly injection.

Indications

Adverse effects

Common

  • Nausea, vomiting, diarrhea, constipation, abdominal pain (most common, mostly at the start)
  • Reduced appetite
  • Injection-site reactions
  • Slightly faster heart rate

Contraindications

  • Personal or family history of medullary thyroid carcinoma
  • Multiple endocrine neoplasia type 2 (MEN 2)
  • Serious hypersensitivity to the drug

Key interactions

Insulin or sulfonylureas
Higher risk of hypoglycemia; their dose is often reduced.
Oral drugs in general
Slower gastric emptying can change their absorption.
Oral hormonal contraceptives
Can be less effective, mostly after starting or raising the dose; another or added method is advised.

What is monitored

  • HbA1c and weight
  • Kidney function if vomiting or diarrhea
  • Symptoms of pancreatitis or gallbladder disease

Administration and safety

  • Subcutaneous injection in the abdomen, thigh or upper arm, rotating sites.
  • Pens are for one person only and are never shared, even with a new needle.
  • The dose is raised step by step to limit nausea.
  • Unopened pens are kept in the refrigerator, not frozen.

Nursing care

  • Before: thyroid history (medullary carcinoma, MEN 2), pancreatitis history, kidney function.
  • During: severe abdominal pain spreading to the back (pancreatitis), vomiting and dehydration.
  • Teach to report a neck lump, hoarseness or trouble swallowing.
  • The anesthesia team is told before surgery or endoscopy.
  • Ask about oral contraceptives and discuss a backup method.

Pregnancy and breastfeeding

Not used in pregnancy (weight loss is not a goal and animal data showed harm); it is stopped ahead of a planned pregnancy.

Test yourself

Think of the answer, then tap the question to see it.

Which two receptors does tirzepatide activate?

The GIP receptor and the GLP-1 receptor.

Why may a woman on tirzepatide need a backup contraceptive method?

Slowed gastric emptying can reduce absorption of oral hormonal contraceptives, especially after starting or raising the dose.

Besides diabetes and obesity, which condition is tirzepatide used for?

Obstructive sleep apnea in adults with obesity.

Add to my cards (3)

← Back to the class: GLP-1 receptor agonists

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: Tirzepatide injection: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); Cryo-EM structure of the tirzepatide-bound human GIPR-Gs complex (RCSB Protein Data Bank, 2022); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); eEML - Electronic Essential Medicines List (World Health Organization, 2025).

Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake

Representative model, for educational purposes only.