Retatrutide (LY3437943)
LY3437943
Clinical trials are ongoing or recently completed. Final approval has not been granted.
An investigational once-weekly injection that works on three different appetite and metabolism pathways at once, producing some of the most significant weight loss results seen in clinical trials -- up to about 29% body weight reduction over about 16 months. It is not yet FDA-approved.
This entry is a cited research summary, not an established treatment reference. Dosing language is included as source context, not as medical instruction.
Safety Summary
Most adverse effects are gastrointestinal, dose-dependent, and concentrated during initial dose-titration; they generally improve with continued use. Discontinuation rates due to AEs in Phase 3 TRIUMPH-4: 12.2% (9 mg), 18.2% (12 mg), 4.0% (placebo). Dysesthesia is a novel signal at higher doses requiring ongoing monitoring -- more frequent in Phase 3 data (~20.9% at 12 mg) than initially suggested by Phase 2 data. Heart rate increases typically peak around 24 weeks then decline. No excess major adverse cardiac events in Phase 2. Rodent C-cell thyroid tumors observed in class-wide nonclinical studies (GLP-1/GIP agonists) -- limited human relevance but a recognized nonclinical signal. Post-discontinuation weight regain is anticipated based on GLP-1RA class data but not yet directly documented for retatrutide, DOI:10.1056/NEJMoa2301972.
Clinical check-in
If real-world use or exposure is being considered, review potential interactions, contraindications, and monitoring needs with a licensed clinician rather than relying on summary copy alone.
Sources: [1-10]