Can an NAD+ pill protect muscle in people taking semaglutide?
Sironax has enrolled about half of its Phase 2 trial testing an oral NAD+ booster alongside semaglutide to preserve lean mass in adults with obesity.
Summary
Weight-loss drugs like semaglutide work, but some of the weight lost is muscle, which matters for strength, balance and independence as we age. Biotech company Sironax says it has reached about 50 percent of its enrollment target in the Phase 2 FORGE-LM trial of SIR4156, an oral pill that activates NAMPT, a key enzyme in making NAD+. NAD+ is a molecule involved in energy and mitochondrial function, and its levels fall with age and metabolic dysfunction. In mouse studies, the company reports the drug produced preferential fat loss, preserved lean mass and improved physical performance. The human trial is randomized, double-blinded and placebo-controlled, and pairs the drug with semaglutide in adults with obesity. Its primary goal is body fat and body composition, with lean mass as a secondary measure. The drug is investigational, and animal results often fail to translate to people.
Detailed Summary
Semaglutide and related GLP-1 drugs have transformed obesity treatment, but the weight they take off is not all fat. Some is lean mass, including muscle. That matters most for older adults, who have less muscle to spare and rely on it for strength, balance and independence. Longevity researchers have therefore watched the muscle question around these drugs closely.
Sironax, a Waltham, Massachusetts biotech, announced on 13 October that it has reached roughly 50 percent of its targeted enrollment in the global Phase 2 FORGE-LM trial. The study is double-blinded, randomized, placebo-controlled and parallel-group. It tests SIR4156, a first-in-class oral allosteric activator of NAMPT, alongside semaglutide in adults with obesity. NAMPT is a rate-limiting enzyme in NAD+ production. NAD+ supports energy regulation and mitochondrial function, and it declines with age and metabolic dysfunction.
The company reports that in multiple preclinical models, SIR4156 produced preferential fat loss, preserved lean mass, reduced muscle atrophy and improved physical performance. Mouse data on restoring tissue NAD+ were presented at the Aging Research and Drug Discovery conference in Boston. The human trial's primary objective is the effect on body fat mass and body composition. Body weight, lean mass, safety, tolerability, pharmacokinetics and pharmacodynamics are secondary objectives.
For readers, the practical message is that nothing here changes what to do today. Muscle loss on GLP-1 therapy is a recognized concern, and the best-supported strategies remain adequate protein and resistance training, which this article does not address. This pill is an experimental approach to a real problem, not an available treatment.
Several caveats apply. Lean mass is a secondary rather than primary endpoint, so a clean muscle-preservation result is not guaranteed. The release omits the enrollment target, treatment length and results timeline, and does not spell out the comparison arms, though semaglutide plus placebo is likely. The data so far come from mice and company statements. SIR4156 is unapproved, and its safety and efficacy in humans are unestablished.
Key Findings
- Sironax reports about 50% of its targeted enrollment reached in the Phase 2 FORGE-LM trial of SIR4156 plus semaglutide.
- SIR4156 is an oral NAMPT activator meant to restore NAD+, which declines with age and metabolic dysfunction.
- Company-reported mouse data show preferential fat loss, preserved lean mass, less muscle atrophy and better physical performance.
- The primary endpoint is fat mass and body composition; lean mass is only a secondary endpoint.
- The drug is unapproved, and the release gives no enrollment target, treatment duration or results date.
Methodology
This is a news report based largely on a company press release about an ongoing Phase 2 trial, published by Longevity.Technology. No human efficacy data are reported; the evidence cited is company-presented preclinical mouse data. The article does add some independent commentary on trial design and gaps.
Study Limitations
The findings are preclinical and company-reported, with no peer-reviewed human data yet. Key trial details, including sample size, duration, comparator arms and timeline, are missing, and lean mass is not the primary endpoint. Check ClinicalTrials.gov and future publications for protocol and results.
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