Weight & Metabolic
Pemvidutide
aka ALT-801 · ALT801 · ALT 801 · pemvi · pemvidutide peptide · altimmune weight loss · altimmune mash drug · pemvidutid · pemvidutyde · pemvidotide · pemvitude
Grade
An experimental weekly injection from Altimmune that hits both GLP-1 and glucagon. It causes weight loss and cuts liver fat, but the company is now developing it for fatty liver disease and alcohol problems rather than as a weight-loss drug, and it is not approved anywhere.
- Class
- GLP-1/glucagon dual receptor agonist peptide; weekly injection
- Evidence
- Grade B · Promising human evidence
- Sport / WADA
- Prohibited at all times under S0 (non-approved substances). The WADA 2026 Prohibited List bans any pharmacological substance not covered elsewhere on the List and with no current approval by any governmental regulatory health authority for human therapeutic use, explicitly including drugs under clinical development.
- Last reviewed
- 2026-10
Grade B · Promising human evidence
Why this grade
Real placebo-controlled human trials, but none has finished Phase 3. In the liver disease MASH, the Phase 2b IMPACT trial (Lancet 2025, 212 people) met its goal for clearing liver inflammation at 24 weeks but missed its goal for reducing scarring (fibrosis) on biopsy. For weight loss, the 48-week Phase 2 MOMENTUM trial (391 people) reported up to 15.6% weight loss versus 2.2% on placebo, but only by company press release; it is not peer reviewed. A smaller 12-week liver-fat study is published (J Hepatol 2025). All trials were run by the manufacturer, Altimmune. A Phase 3 trial in MASH (PERFORMA) began in 2026; there is no Phase 3 trial for weight loss. No regulator has approved it.
What is it?
Why people buy it
People are interested in it to lose weight. The company is testing it mainly for a serious fatty liver disease.
What we actually know
- •It copies two natural hormones. One makes you feel full. The other makes the liver burn more fat.
- •In a year-long weight study, people on the top dose lost about 16% of their weight. That study has not been fully published.
- •In people with liver disease, it cleared signs of liver inflammation in about half of people. It did not clearly reduce liver scarring.
- •It is still being tested. It is not a licensed medicine in the UK or anywhere else.
What might happen
- •Weight loss looks likely. Less fat in the liver also looks likely.
- •Feeling sick and being sick were common at higher doses in the weight study.
- •In that study, about 1 in 6 people on the higher doses stopped because of side effects.
- •Long-term safety is unknown.
- •Anything sold online under this name is not checked. Nobody knows what is really in it.
- •It is banned in sport at all times, because it is not an approved medicine.
Bottom line
Real results in people, mostly for the liver. As a weight-loss drug it is not being taken forward to final testing.
Know someone taking this?
Send on WhatsAppPemvidutide is like a cleaner hired for the whole house who turned out to be best at the kitchen. It did tidy up the weight, but the company now has it working on the liver. The weight-loss job never got its final inspection.
How is it meant to work?
A dual agonist peptide that activates both the GLP-1 receptor and the glucagon receptor. GLP-1 activity reduces appetite and food intake and slows gastric emptying. Glucagon activity acts directly on the liver, increasing fat burning (fatty acid oxidation) and reducing new fat production. Given by once-weekly subcutaneous injection in trials.
What's it studied for?
Research contexts. Not proven uses, and not recommendations.
Does the human evidence stack up?
Moderate and mixed. Published: a 12-week liver-fat study (J Hepatol 2025, n=94) showing large reductions in liver fat, and the 24-week IMPACT Phase 2b MASH trial (Lancet 2025, n=212), which met its inflammation-resolution endpoint but missed its biopsy fibrosis endpoint. Not peer reviewed: the 48-week MOMENTUM obesity trial (n=391; up to 15.6% weight loss versus 2.2% on placebo) and 48-week IMPACT data based on non-invasive markers. Gastrointestinal side effects were common in MOMENTUM, with notable dropout at higher doses. All trials were sponsored by Altimmune. There are no Phase 3 results and no long-term safety data.
What could go wrong?
- !Not licensed by the MHRA or any other regulator. Its benefit-risk balance has not been signed off for any use
- !In MOMENTUM, nausea affected up to 59.6% and vomiting up to 27.8% (versus 11.3% and 3.1% on placebo), and about 16% stopped on the two higher doses because of drug-related side effects
- !The headline weight-loss figures come from a company press release and filing, not a peer-reviewed paper
- !In MASH, the biopsy fibrosis endpoint was missed at 24 weeks; later fibrosis claims rely on non-invasive markers
- !There is no Phase 3 weight-loss programme, so its weight-loss use is unlikely to be tested further
- !No long-term safety data
- !GREY MARKET: anything sold online as 'pemvidutide' or 'ALT-801' is unlicensed and outside regulatory oversight. Identity, dose, purity and sterility are unverified and it is not the trial product
Is it legal in the UK?
Investigational drug, not a licensed UK medicine. The MHRA has not granted a marketing authorisation, and it is not available on prescription or the NHS. Legitimate access is only through a registered clinical trial. Products sold to UK buyers under the name 'pemvidutide' are unlicensed research chemicals; supplying it for human use would breach the Human Medicines Regulations 2012.
Key trials
- NCT05989711· Phase 2b· Completed
IMPACT: Pemvidutide in MASH with fibrosis
212 participants; 24-week results published in The Lancet 2025.
- NCT07795164· Phase 3· Recruiting
PERFORMA: Pemvidutide in MASH
About 1,800 participants planned; started July 2026.
- NCT06987513· Phase 2· Completed
RECLAIM: Pemvidutide in alcohol use disorder
100 participants, 24 weeks; results by company release only.
Sources
- 01Safety and efficacy of weekly pemvidutide versus placebo for metabolic dysfunction-associated steatohepatitis (IMPACT): 24-week results from a multicentre, randomised, double-blind, phase 2b study — Noureddin M, et al., The Lancet (2025)
n=212; MASH resolution 58% and 52% vs 20% placebo; fibrosis improvement endpoint not met at 24 weeks.
- 02Effect of pemvidutide, a GLP-1/glucagon dual receptor agonist, on MASLD: A randomized, double-blind, placebo-controlled study — Harrison SA, et al., Journal of Hepatology (2025)
n=94; 12 weeks; liver fat reductions up to 68.5% vs 4.4% placebo; weight loss up to 4.3%.
- 03Altimmune Form 8-K: topline results from 48-week MOMENTUM Phase 2 obesity trial of pemvidutide, Altimmune / US SEC filing (2023)
n=391; 10.3%, 11.2%, 15.6% vs 2.2% placebo at 48 weeks; nausea, vomiting and discontinuation rates. Not peer reviewed.
- 04Altimmune second quarter 2026 results and business update, Altimmune / US SEC filing (2026)
PERFORMA Phase 3 MASH trial initiated (52-week data expected 2029); RECLAIM alcohol use disorder results; no obesity programme listed.
- 05World Anti-Doping Code International Standard: Prohibited List 2026, World Anti-Doping Agency (2026)
S0 non-approved substances: drugs under clinical development are prohibited at all times.
Related
Before you trust a vial
Peptides are freeze-dried for a reason. If you have seen Pemvidutide sold pre-mixed in a ready-to-use pen or syringe, here is why that is a red flag for potency, sterility and dosing.
Storage & stability →Stay posted
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