Tirzepatide
A dual GLP-1 and GIP receptor agonist — marketed as Mounjaro for type 2 diabetes and as Zepbound for obesity.
Why it matters
Tirzepatide combines GLP-1 agonism (which slows gastric emptying and increases satiety) with GIP agonism (which adds insulin secretion and adipose-tissue effects). Phase 3 weight-loss data show ~21% body weight reduction over 72 weeks at the highest dose — larger than semaglutide.
In practice
Prescribed as a weekly subcutaneous injection. The titration schedule starts at 2.5mg and steps up to therapeutic doses to minimise GI side effects. Research-market tirzepatide is sold but not regulated as a pharmaceutical.
Common confusion
Tirzepatide and semaglutide are not interchangeable — the dual mechanism produces a distinct effect and side-effect profile.
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