Late-stage trial data for retatrutide shows obese patients on the highest dose lost an average of 25 percent of their body weight after 80 weeks, as pharmaceutical companies accelerate development of multi-hormone receptor agonists for conditions ranging from severe weight management to alcohol-use disorder and obstructive sleep apnea.
Clinical Trial Results for Retatrutide and Triple Hormone Action
Late-stage clinical trial data released for retatrutide, developed by Eli Lilly, detail how the triple hormone receptor agonist interacts with the human body. The trial began in 2023 and included 2,339 participants across 131 clinical trial sites in 11 countries. Participants were divided into four groups, receiving either 4 mg, 9 mg, 12 mg, or a placebo. At the start of the study, participants averaged approximately 113 kg (250 pounds) with an average body mass index of 40.
According to findings shared in the New England Journal of Medicine, individuals struggling with obesity who received the maximum 12 mg dosage shed a mean 25 percent of their initial mass by week 80, which further improved to a mean 30 percent reduction following an extended trial duration of 104 weeks. Overall, more than a third of subjects taking the drug lost 30 percent or more of their body weight. Unlike medications that target only one or two pathways, retatrutide acts for three distinct hormones: glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and glucagon.
Impact on Knee Osteoarthritis and Sleep Apnea Symptoms
Beyond weight loss, subsets of clinical trial participants experienced measurable improvements in obesity-related secondary conditions. Of the total participants, 574 suffered from osteoarthritis of the knee, and 243 suffered from obstructive sleep apnea syndrome. Patients with knee osteoarthritis reported a reduction in knee pain of up to 62 percent. Additionally, participants with sleep apnea recorded a reduction in breathing interruptions per hour of up to 57 percent.
Two randomized phase III trials, TRIUMPH-1-OSA and TRIUMPH-2-OSA, specifically evaluated retatrutide in adults with moderate-to-severe obstructive sleep apnea and a body mass index of at least 27. While TRIUMPH-1-OSA recruited 243 subjects without type 2 diabetes, TRIUMPH-2-OSA incorporated 448 individuals diagnosed with the condition. In TRIUMPH-1-OSA, participants receiving the 9 mg dose experienced an average reduction of 34.3 breathing events per hour, compared with 9.9 events in the placebo group. Participants in TRIUMPH-2-OSA taking 9 mg and 12 mg doses saw reductions of 24.7 and 25.4 breathing events per hour, respectively, compared with 10.3 events for placebo recipients.
Cardiometabolic Improvements and Pre-Diabetes Resolution
Trial results demonstrated broad enhancements across cardiovascular and metabolic indicators. Participants showed improvements in blood pressure, triglycerides, and low-density lipoprotein cholesterol, commonly known as bad cholesterol. At the start of the study, more than one-third of participants had prediabetes. By the end of the trial, that condition had resolved in more than 90 percent of those participants. The safety profile of retatrutide appeared comparable to existing GLP-1 and dual-receptor medications, with temporary, mild-to-moderate gastrointestinal symptoms such as nausea, diarrhea, and constipation reported as the most frequent adverse events.
Expanding Applications for Brain Disorders and Substance Use
Pharmaceutical development in the GLP-1 class has extended beyond weight management and metabolic disease into neurology and psychiatry. Academic studies published in 2025 demonstrated that semaglutide reduced alcohol cravings and heavy drinking episodes over time in people with alcohol-use disorder. These findings spurred commercial development of related compounds tailored with longer half-lives suitable for psychiatric and substance-use conditions.
Eli Lilly presented clinical results for brenipatide, a GIP and GLP-1 mimic featuring a half-life of 9 to 12 days compared to the 5 to 7 days typical of approved medications, tested for alcohol-use disorder. Brenipatide is also in clinical trials for tobacco and opioid-use disorders, depression, schizophrenia, and bipolar disorder. Robert Nicholson, who leads medical affairs for psychiatry and substance-use disorders at Eli Lilly, noted that the extended duration makes the compound suitable for patients managing psychiatric conditions.
With the industry trials coming online, we’ll see this area of work grow even more quickly in the next couple of years, Hopefully that will lead to one or more FDA approvals for GLP-1 therapies for addiction.
Christian Hendershot, addiction scientist at the University of Southern California in Los Angeles