Week 43 | October 19–23, 2026
Story of the Week: Retatrutide Cuts Breathing Interruptions During Sleep by Dozens per Hour
Remember tirzepatide, the drug that mimics two gut hormones at once? Its "younger sibling" goes even further. Retatrutide from Eli Lilly is a so-called triple agonist: in addition to the GIP and GLP-1 receptors, it also activates the receptor for glucagon, a hormone involved in burning energy.
At the European congress Sleep Europe 2026, held October 20–23 in Maastricht, the Netherlands, researchers presented results from two phase III trials focused on obstructive sleep apnea. The studies were also published in the New England Journal of Medicine.
What the trials looked at:
- TRIUMPH-1-OSA: 243 adults with moderate to severe sleep apnea and overweight or obesity, without diabetes.
- TRIUMPH-2-OSA: 448 adults with the same diagnosis who had type 2 diabetes.
- Both trials lasted 80 weeks and compared retatrutide with placebo.
What they showed:
- In people without diabetes, the number of breathing pauses and reductions per hour of sleep (the so-called AHI) fell by about 34 at the middle dose tested, compared with about 10 on placebo.
- In people with diabetes, the AHI fell by about 25 at the higher doses, compared with about 10 on placebo.
- Participants without diabetes lost 12.5% to 22.2% of their body weight (4.8% on placebo), and participants with diabetes lost 12.1% to 18.5% (5.6% on placebo).
Why it matters: Sleep apnea affects a large number of people with obesity. Breathing stops repeatedly during sleep, people wake up tired, and over time it puts strain on the heart and blood vessels. Until now, it has mainly been treated with a device that keeps the airways open during sleep. In December 2024, tirzepatide became the first drug approved in the US for this condition. Retatrutide now shows that adding a third hormonal signal can deliver similarly strong, or even stronger, results. It is still an investigational drug awaiting approval.
Read more: We took a detailed look at how tirzepatide works and what its trials showed in our article Tirzepatide: How It Works and What the Trials Showed. Retatrutide is covered in Retatrutide: Mechanism of Action and Trial Results.
CagriSema: Women Lost an Average of a Quarter of Their Body Weight
The second big story of the week came from Danish company Novo Nordisk. At The Menopause Society 2026 Annual Meeting in San Diego, researchers presented new analyses of the drug CagriSema. They were covered by CNBC (October 20) and Pharmacy Times (October 22), among others.
What CagriSema is: A once-weekly injection that combines two peptides:
- semaglutide, which mimics the gut hormone GLP-1,
- cagrilintide, which mimics the hormone amylin. The pancreas releases amylin together with insulin, and in the brain it helps create a feeling of fullness.
The two peptides therefore act on satiety from two different angles.
What the analyses showed: They were based on the phase III trial REDEFINE 1, which included 3,417 adults with obesity or overweight without diabetes and lasted 68 weeks. Women made up about two-thirds of the participants.
- Women treated with CagriSema lost an average of 25% of their body weight. With semaglutide alone, it was 19%; with cagrilintide alone, 13.4%; and with placebo, 3%.
- The results were strong across all life stages: premenopausal women lost an average of 26.7%, perimenopausal women 24.8% and postmenopausal women 23.1%. On placebo, it was just 1.7% to 2.6%.
Why it matters: Many women say losing weight gets harder around menopause. These analyses suggest that CagriSema works well in postmenopausal women, too. The authors stress that these are post hoc analyses that need to be confirmed in further studies. Novo Nordisk submitted an application for approval to the US FDA in December 2025, and a decision is expected by the end of 2026.
US: The Government Wants a Regulated Peptide Market
In the United States, the debate over how to make certain peptides that are not yet approved as drugs available to people moved forward this week.
How we got here:
- In April 2026, the US Food and Drug Administration (FDA) removed 12 peptides from the category of substances that pharmacies were not allowed to compound and sent them to an expert panel for review.
- In July 2026, an FDA advisory committee recommended adding six peptides to the list of substances pharmacies may compound: BPC-157, TB-500, KPV, MOTS-c, Semax and Epitalon.
- On October 14, the Department of Health and Human Services (HHS) and the FDA sent a so-called interim peptide access policy to the White House for review. It would allow pharmacies to compound some of these peptides for individual patients until permanent rules are in place.
What happened this week:
- According to the regulatory news site RAPS (October 23), Health Secretary Robert F. Kennedy Jr. reiterated that he wants to create a regulated market for selected peptides, overseen by individual states. He argues this would protect people better than sourcing peptides from unverified suppliers.
- Bloomberg (October 22) reported that the plan would require pharmacies to report side effects. This would start generating data on how peptides perform in practice.
What's next: The interim policy has not yet been issued, and the plan also has its critics. A second committee meeting, which is to review five more peptides (GHK-Cu, LL-37, Dihexa, Melanotan II and PEG-MGF), is expected by the end of February 2027.
Why it matters in Europe too: The US sets the trends in the peptide world. FDA decisions often become a benchmark that shapes the debate in other countries as well. In the EU, nothing has changed yet in how these peptides are regulated.
Read more: We wrote about MOTS-c, one of the six recommended peptides, in our article MOTS-c: The Exercise Peptide Made by Your Mitochondria. Melanotan II, which is awaiting review, is covered in Melanotan II: History, Mechanism and Research Explained.
The Week in Brief
- Retatrutide significantly reduced breathing interruptions during sleep in two phase III trials, and people lost more than a fifth of their body weight. The results were presented at the European congress Sleep Europe in Maastricht.
- CagriSema helped women lose an average of a quarter of their body weight, including after menopause.
- In the US, an interim policy is getting closer that would allow pharmacies to compound some peptides, including BPC-157 and MOTS-c, in a regulated setting.
We'll be back with the next roundup next week.
Sources
- Grunstein RR, et al. "Retatrutide Once Weekly for Treatment of Obstructive Sleep Apnea." New England Journal of Medicine, 2026. DOI: 10.1056/NEJMoa2611477: nejm.org
- EMJ – Retatrutide Cuts Sleep Apnea Events in Phase III Trials: emjreviews.com
- ESRS – Sleep Europe 2026, Maastricht, October 20–23, 2026: esrs.eu
- Pharmacy Times – CagriSema Tied to 25% Weight Loss in Women, Post Hoc Data Show (October 22, 2026): pharmacytimes.com
- CNBC – Novo's CagriSema shows 25% weight loss in women (October 20, 2026): cnbc.com
- RAPS – This Week at FDA: Peptide dispute, clinical trial legislation, and more (October 23, 2026): raps.org
- Bloomberg – RFK Jr. Pushes Peptide Access, Compounding Pharmacies Face New Reporting Rules (October 22, 2026): bloomberg.com
- Holland & Knight – Peptides at a Crossroads: What Wellness Providers Need to Know About HHS and FDA Actions (October 16, 2026): hklaw.com
- AJMC – FDA Panel Backs 6 Peptides for Compounding (July 31, 2026): ajmc.com