Tirzepatide is approved for type 2 diabetes and obesity and shows superior HbA1c reduction compared to semaglutide. Its unique pharmacology compared to GLP-1 receptor agonists is:
- A It is a dual agonist at GLP-1 receptors and glucagon receptors, reducing hepatic glucose output
- B It is a dual agonist at GLP-1 receptors and GIP (glucose-dependent insulinotropic polypeptide) receptors, with GIP component also augmenting adipose fatty acid metabolism ✓
- C It is a triple agonist at GLP-1, GIP, and glucagon receptors (similar to retatrutide)
- D It is a selective GIP receptor agonist with no activity at GLP-1 receptors
Explanation
Tirzepatide is a GIP/GLP-1 receptor dual agonist (a 'twincretin'), activating both GIP receptors and GLP-1 receptors. GIP acts synergistically with GLP-1 to augment glucose-dependent insulin secretion, suppress glucagon, and in adipose tissue promotes fatty acid uptake and storage — reducing ectopic lipid deposition. The GIP component may also reduce the nausea from GLP-1R stimulation and contribute to superior weight loss and glycaemic control seen in SURPASS trials compared to semaglutide. The triple GLP-1/GIP/glucagon agonist is retatrutide (a distinct investigational molecule).
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
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Written and medically reviewed by the StethoPrep medical team.