Pemvidutide is an investigational peptide drug from Altimmune, developed under the code name ALT-801. It activates two receptors at once: the GLP-1 receptor and the glucagon receptor. That dual action is the whole idea. GLP-1 signaling reduces appetite, while glucagon signaling pushes up energy expenditure and acts on the liver to burn fat and curb new fat production. Altimmune frames the combination as mimicking the complementary effects of diet and exercise.
It is dosed once weekly by subcutaneous injection. That schedule comes from a proprietary half-life extension technology Altimmune calls EuPort, which binds the peptide to albumin in the blood so it clears more slowly.
What it is being studied for
Two conditions, mainly: obesity and metabolic dysfunction-associated steatohepatitis (MASH, the more advanced form of fatty liver disease, formerly called NASH). There has also been work in MASLD, the broader fatty-liver category.
Pemvidutide is not an approved drug. It remains investigational and is being evaluated in clinical trials. Nothing here is medical or dosing advice.
The evidence so far
Obesity (MOMENTUM, Phase 2). This 48-week placebo-controlled trial randomized 391 adults with overweight or obesity to one of three weekly doses or placebo. At week 48, mean weight loss was 10.3%, 11.2%, and 15.6% at the 1.2 mg, 1.8 mg, and 2.4 mg doses, against 2.2% on placebo, as presented at the American Diabetes Association's 2024 Scientific Sessions.
Fatty liver (MASLD, Phase 2). A 12-week double-blind study in 94 patients with liver fat content of at least 10% reported a 68.5% relative reduction in liver fat at the 1.8 mg dose versus 4.4% on placebo, with more than half of patients on that dose normalizing liver fat to 5% or less. The drug was well tolerated, with no severe or serious adverse events reported. The results were published in the Journal of Hepatology in 2024.
MASH (IMPACT, Phase 2b). This is the program that has drawn the most attention. At 24 weeks, MASH resolution without worsening of fibrosis was reached in 59.1% and 52.1% of patients on the 1.2 mg and 1.8 mg doses. The 48-week data, reported in late 2025, showed continued improvement on non-invasive fibrosis tests including Enhanced Liver Fibrosis (ELF) and Liver Stiffness Measurement (LSM), with weight loss of 4.5% and 7.5% at the two doses versus 0.2% on placebo. The 24-week phase 2b results were published in The Lancet02304-9/abstract?rss=yes).
Not every readout has been uniformly positive, and the MASH data have been described by some observers as mixed, partly because weight loss at the doses used in IMPACT was more modest than in the obesity trial. Worth reading the trial reports directly rather than relying on summaries.
Regulatory status
In January 2026 the FDA granted pemvidutide Breakthrough Therapy Designation in MASH, based on the 24-week IMPACT data. Altimmune has said it intends to begin a registrational Phase 3 trial in MASH in 2026. The drug has no marketing approval anywhere, and we found no record of a specific WADA prohibited-list entry for pemvidutide by name; as an unapproved investigational agent it should be treated as research-use-only.
The buyer-quality angle
Because pemvidutide is not approved, any material sold under its name or the ALT-801 code outside a clinical trial is unregulated. There is no pharmacy-grade supply chain behind it. If you are looking at a vial from a research-chemical vendor, the label claim is just a claim until a third party verifies it. The things that actually matter are identity and purity: a recent, batch-specific certificate of analysis (COA) from an independent lab, ideally with mass-spec confirmation of identity and HPLC purity. peptideone aggregates third-party COA and vendor-rating signals so you can see what has actually been tested rather than what a product page asserts. Independent testing is the only real check on whether a vial contains what it says.