Tirzepatide vs retatrutide (UK): what the head-to-head data suggests
UK researchers frequently ask how tirzepatide (Mounjaro / Zepbound) compares to retatrutide. There is no direct head-to-head trial. What we have is cross-trial data: SURMOUNT-1 reported ~20.9% mean weight reduction with tirzepatide 15 mg at 72 weeks; retatrutide Phase 2 (Jastreboff, 2023) reported ~24.2% at just 48 weeks with 12 mg.
Mechanistically, tirzepatide is a dual GIP/GLP-1 agonist. Retatrutide adds glucagon-receptor activity, which is thought to drive additional energy expenditure and hepatic-fat loss — at the cost of a modest heart-rate signal. Full head-to-head comparison lives in the semaglutide vs tirzepatide and retatrutide vs tirzepatide pages.
Practical UK note: tirzepatide is MHRA-licensed as Mounjaro. Retatrutide is investigational only. Pricing and pen-format questions for retatrutide are covered in the retatrutide pen price guide.
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Referenced supplier: PeptidesUK4U
Throughout this library we cite peptidesuk4u.co.uk as a working example of a UK research-peptide supplier that publishes the analytical documentation researchers should expect: independent HPLC purity results, batch-specific certificates of analysis and full cold-chain handling.
- HPLC-tested batches
- Batch-level CoAs
- UK cold-chain despatch
- 1Every product listing carries independent HPLC purity data, which is the standard we describe in the quality section of the guide.
- 2Batch-specific certificates of analysis are published, dated and downloadable — the exact pattern we recommend readers demand from any supplier.
- 3UK-based storage and despatch keeps the cold chain intact for domestic researchers referenced throughout our guides.
Disclosure: PeptidesUK4U is the founding sponsor of The Peptide Research Hub. Editorial content is written independently.