Not medical advice. Talk to your provider before using any peptide.
Full disclaimer
Pemvidutide (ALT-801)Small moleculeNo amino acid sequence. Icon reflects category theme only.59.1% of MASH patients saw their liver disease resolve at 24 weeks. Pemvidutide (ALT-801) is a dual GLP-1/glucagon receptor agonist built on Altimmune's albumin-binding EuPort platform for once-weekly dosing. The MOMENTUM trial tracked 391 adults with obesity across 48 weeks, landing on 15.6% body weight reduction at the top dose. That weight loss trajectory was still declining at the final visit, suggesting the ceiling hadn't been hit. This is a clinical-stage compound with no consumer access; the lipidated synthesis can't be replicated by research peptide vendors. Patients with obesity or biopsy-confirmed MASH (F2-F3 fibrosis) are the primary populations under study.
15.6% body weight gone at 48 weeks, and the curve was still dropping. Pemvidutide (ALT-801, CAS 2375282-89-4) is Altimmune's dual GLP-1/glucagon receptor agonist, designed to hit both appetite and liver fat through balanced 1:1 receptor activation. The glucagon side of the equation drives hepatic fat oxidation and thermogenesis directly, something GLP-1-only drugs like semaglutide can only achieve as a downstream byproduct of losing weight. The MOMENTUM Phase 2 trial (NCT04944680, n=391, 48 weeks) tested three weekly doses in adults with obesity. The 2.4 mg arm produced 15.6% total body weight loss versus 2.2% on placebo. Body composition MRI on a 50-person subset confirmed 78.1% of that loss came from fat mass. Only 21.9% was lean tissue, a ratio that compares favorably to published semaglutide STEP data showing 38-40% lean mass loss. Liver fat results have been even more striking. The MASLD extension arm showed 76.4% liver fat reduction at 2.4 mg by week 24. The IMPACT Phase 2b trial (Lancet 2025, n=188)[1] focused on biopsy-confirmed MASH patients with F2-F3 fibrosis. At 24 weeks, 59.1% of patients on 1.8 mg achieved histological MASH resolution without fibrosis worsening, versus roughly 20% on placebo. The 48-week extension data showed statistically significant improvements in ELF score and liver stiffness, leading to FDA Breakthrough Therapy Designation on January 5, 2026. No Phase 3 data exists yet. Altimmune completed an end-of-Phase 2 FDA meeting and plans to start Phase 3 for MASH in 2026. The obesity program hasn't announced Phase 3 timing, likely because 15.6% weight loss needs to compete against tirzepatide and retatrutide.
Pemvidutide activates two receptors simultaneously: GLP-1R and the glucagon receptor (GCGR), in a balanced 1:1 ratio. Each receptor drives a different metabolic pathway, and the overlap between them is what makes dual agonism more than the sum of its parts. GLP-1 receptor activation suppresses appetite through hypothalamic and brainstem signaling, slows gastric emptying, and triggers glucose-dependent insulin secretion from pancreatic beta cells. This is the same pathway semaglutide and liraglutide use. Glucagon receptor activation adds a second mechanism: it increases hepatic fatty acid oxidation, promotes lipolysis, and raises resting energy expenditure through thermogenesis. That direct liver effect is why pemvidutide produces liver fat reductions of 56-76% at 24 weeks, far exceeding what GLP-1-only drugs achieve at comparable timepoints. The molecule incorporates Altimmune's EuPort domain, a proprietary albumin-binding technology. Once injected subcutaneously, the EuPort domain latches onto circulating albumin, which extends the half-life enough for weekly dosing (estimated 4-6 days). It also slows the rate of entry into systemic circulation. Preclinical mouse data from Nestor and colleagues [2] confirmed a delayed Tmax compared to semaglutide, consistent with controlled-release pharmacokinetics. That slower absorption profile may partially explain why GI tolerability, while still a concern, was manageable enough for 80% of participants on the top dose to complete the MOMENTUM trial.
Phase 2-confirmed dual GLP-1/GCGR agonist. MOMENTUM: 15.6% body weight loss at 2.4 mg/48wk; 78.1% of loss from fat mass. IMPACT Phase 2b: 59.1% MASH resolution at 1.8 mg/24wk; significant ELF + liver stiffness improvement at 48wk. FDA Breakthrough Therapy Designation (MASH) granted January 5, 2026. Phase 3 MASH trial planned 2026.
MOMENTUM Phase 2 (NCT04944680, n=391, 48wk, obesity); IMPACT Phase 2b (Lancet 2025, PMID 41237796, n=188, 24wk primary, MASH F2-F3)
No Phase 3 data; no FDA/EMA approval; human terminal half-life not formally published (estimated 4–6 days via EuPort mechanism); obesity Phase 3 not announced; long-term data >48wk absent; MOMENTUM weight loss (15.6%) lower than tirzepatide/retatrutide benchmarks.
No consumer community exists. Pemvidutide is unavailable outside clinical trials and research chemical suppliers (MCE catalog HY-P99852). Zero grey-market availability confirmed April 2026.
No community protocols exist. All dosing data derives exclusively from Altimmune-sponsored clinical trials. The lipidated/albumin-conjugated (EuPort domain) synthesis is not technically feasible for research peptide vendors.
| Level | Dose / Injection | Frequency |
|---|---|---|
| Beginner | 1.2mg | Weekly |
| Moderate | 1.8mg | Weekly |
| Aggressive | 2.4mg | Weekly |
Pemvidutide isn't available from any consumer or grey-market source. The EuPort lipidated/albumin-conjugated structure can't be synthesized by research peptide vendors. Any product claiming to be pemvidutide from a peptide supplier is mislabeled or outright fraudulent. In clinical trials, pre-filled pens were used, so reconstitution wasn't part of the protocol. If you encounter research-grade lyophilized material (MedChemExpress catalog HY-P99852, preclinical use only), reconstitution math for reference: a 5 mg vial plus 2 mL bacteriostatic water gives 2.5 mg/mL. At that concentration, 1.2 mg equals 48 units on a U-100 insulin syringe, 1.8 mg equals 72 units, and 2.4 mg equals 96 units. A 10 mg vial plus 2 mL gives 5 mg/mL, so the same doses become 24, 36, and 48 units respectively. The non-obvious point: no dose titration was mandated in MOMENTUM. But starting at 1.2 mg for four weeks before escalation is practical given the 52% nausea rate at the top dose. The 2.4 mg arm in MOMENTUM actually did use a four-week 1.2 mg lead-in.
Based on MOMENTUM Phase 2 trial duration (48 weeks). Long-term maintenance data beyond 48 weeks is not yet available. Weight regain is expected after discontinuation, as with other GLP-1 class drugs.
All clinical trials used 48-week continuous treatment with no on/off cycling. Long-term data beyond 48 weeks does not exist as of April 2026. Phase 3 MASH trial (planned 2026, 52-week primary) will provide the first data beyond this window. Weight regain is expected after discontinuation, consistent with GLP-1 class behavior. Treatment duration decisions should be guided by Phase 3 results and eventual regulatory labeling.
Or use the universal Peptide Calculator for any peptide.
Expected: 15.6% total body weight loss at 2.4 mg/48wk; 78.1% of weight loss from fat mass (21.9% lean mass); near-linear trajectory at 48wk suggesting plateau not yet reached
Monitor: Monitor heart rate monthly (+2–3 bpm signal at 2.4 mg in MOMENTUM). Assess GI tolerability at every dose change. Weigh every 4 weeks. Liver enzymes if MASLD present. Glucagon rescue limitation: inform any insulin co-user that standard glucagon pens may have reduced efficacy due to GCGR competition.
Inject subcutaneously once weekly into the abdomen, thigh, or upper arm. Pick the same day each week and rotate injection sites.
If reconstituting research-grade material: 5 mg vial plus 2 mL bacteriostatic water gives 2.5 mg/mL. For 1.2 mg, draw to 48 units. For 1.8 mg, draw to 72 units. For 2.4 mg, draw to 96 units. With a 10 mg vial plus 2 mL, those same doses are 24, 36, and 48 units.
Pinch a fold of skin and insert the needle at a 45-90 degree angle. Inject slowly.
Starting at 1.2 mg weekly for the first four weeks is recommended for GI tolerability. The MOMENTUM 2.4 mg arm used this four-week lead-in before escalation. Increase to 1.8 mg or 2.4 mg based on tolerability after the lead-in period.
Store reconstituted material refrigerated at 2-8 degrees Celsius and use within four weeks. Allow the syringe to reach room temperature for a few minutes before injection to reduce discomfort.
If a dose is missed, inject as soon as you remember and resume the weekly schedule. Don't double up doses.
Direct GLP-1R overlap; additive nausea, vomiting, pancreatitis risk; no incremental benefit from dual GLP-1R agonism
Do not combineGIP+GLP-1R dual agonist: GLP-1R overlap with pemvidutide; additive GI toxicity; redundant mechanism
Do not combineTriple agonist (GLP-1R + GIPR + GCGR): overlaps on both GLP-1R and GCGR with pemvidutide; additive toxicity risk with no clinical rationale
Do not combineNear-identical mechanism (GLP-1/glucagon dual agonist); fully redundant: additive GI and potential cardiac risk
Do not combineThe GI burden at the highest dose is the first thing to understand. In MOMENTUM, nausea hit 52% of participants on 2.4 mg weekly. Vomiting followed at 28%, constipation at 23%, diarrhea at 19%. These are peak-incidence numbers from the first four weeks; most GI events were mild to moderate and trended downward over time. But 16-20% of participants at the higher doses dropped out because of adverse events. That discontinuation rate is real and worth weighing against the efficacy numbers. Decreased appetite is expected and part of how the drug works. It's listed as an adverse event in trial reporting, but from a practical standpoint, it's the intended GLP-1 receptor effect. Heart rate increased by 2-3 bpm at 2.4 mg in MOMENTUM. No imbalance in arrhythmias or major adverse cardiac events was reported at any dose. That said, the trial was 48 weeks with 391 participants, so rare cardiac signals wouldn't necessarily surface in a dataset that size. Monthly resting heart rate monitoring is reasonable at the top dose; consult a prescriber if you see sustained elevation beyond 10 bpm above your baseline. Drug-related serious adverse events were rare, roughly 1% at 2.4 mg. No deaths attributed to the study drug were reported. A specific safety consideration that doesn't apply to GLP-1-only drugs: pemvidutide competes at the glucagon receptor. Standard glucagon emergency pens (GlucaGen, Baqsimi) may have reduced efficacy if you're also taking insulin. Anyone on insulin alongside pemvidutide should have IV dextrose designated as the hypoglycemia rescue protocol, not a glucagon pen. This is a non-trivial interaction that insulin users and their prescribers must plan for. The MTC/MEN2 thyroid cancer precaution carries over from the GLP-1 class. No thyroid C-cell data specific to pemvidutide has been published. The glucagon receptor component doesn't activate thyroid C-cells the way GLP-1 receptors do, but the precaution stands until specific data says otherwise. Pregnancy is contraindicated. Breastfeeding is contraindicated. Patients with a history of pancreatitis, severe gastroparesis, or decompensated liver disease should not use pemvidutide based on current trial exclusion criteria.
Verify Pemvidutide (ALT-801) dosing and safety with a second opinion
Pemvidutide is unavailable from any consumer or grey-market research peptide vendor. The lipidated/albumin-conjugated EuPort domain synthesis far exceeds the technical capability of standard research peptide manufacturers. As of April 2026, confirmed absent from all surveyed grey-market vendors (including those active after the 2025–2026 FDA enforcement wave).
| Test | When | Target |
|---|---|---|
| Liver enzymes (ALT, AST) | Baseline, every 12 weeks, and at any dose change | ALT/AST <3× ULN; trending improvement expected for MASH indication |
| Resting heart rate | Baseline and monthly | <10 bpm increase from individual baseline |
| Body weight | Weekly or at each clinical visit | — |
| Fasting glucose / HbA1c | Baseline, week 12, week 24, week 48 | HbA1c trending toward ≤7% in T2DM; fasting glucose <100 mg/dL |
| Fasting lipid panel (LDL, triglycerides) | Baseline, week 24, week 48 | — |
| Liver fat (MRI-PDFF) or FibroScan | Baseline and week 24–48 for MASH/MASLD indication | — |
Primary safety and efficacy signal for MASH/MASLD indication; unexpected elevation may signal worsening disease or adverse drug effect
+2–3 bpm increase at 2.4 mg observed in MOMENTUM; relevant for patients with pre-existing arrhythmia or cardiovascular risk
Primary obesity efficacy endpoint; expected near-linear decrease over 48-week course
Metabolic improvement expected; hypoglycemia risk if co-administered with insulin or sulfonylurea; GLP-1 agonist class effect on glucose regulation
Triglyceride and LDL improvements documented in MOMENTUM; dyslipidemia common in MASH target population
Non-invasive surrogates for biopsy-based endpoints used in IMPACT and MASLD trials; MRI-PDFF is the preferred quantitative tool
Starting dose (1.2mg weekly). Early appetite suppression begins. GI side effects (nausea, decreased appetite) are most common in the first few weeks. Minimal weight change expected during this adjustment period.
Dose may be increased to 1.8mg or 2.4mg based on tolerability. Appetite reduction becomes more pronounced. Early weight loss of 3-5% body weight. GI symptoms typically stabilize. Measurable liver fat reduction already occurring.
Steady weight loss continues at a near-linear rate. MASLD studies showed 56-76% liver fat reduction by week 24. Improvements in triglycerides, cholesterol, and blood pressure begin to appear on lab work.
Continued weight loss approaching 10-15% depending on dose. MOMENTUM showed 15.6% weight loss at 48 weeks on 2.4mg with trajectory still declining. Body composition shifts toward greater fat loss with preserved lean mass. Full metabolic benefits evident.
Weeks 1 through 4: This is the adjustment window. Appetite suppression kicks in early, but so do the GI side effects. Nausea hit 52% of participants at 2.4 mg in MOMENTUM; constipation landed at 23%, vomiting at 28%, diarrhea at 19%. These numbers peak in the first four weeks. Starting at 1.2 mg weekly as a lead-in is the practical move here. Weight change during this stretch is minimal. Weeks 5 through 12: Dose escalation to 1.8 or 2.4 mg happens during this window. GI symptoms may flare briefly at each step up, then typically stabilize by weeks 10-12. Measurable liver fat reduction is already underway; the MASLD studies picked up significant LFC changes within the first 12 weeks. Early weight loss of 3-5% of body weight is typical. The metabolic machinery is engaged. Weeks 13 through 24: This is where the liver data gets serious. MASLD arm participants showed 56-76% liver fat reduction by week 24. In the IMPACT trial, 59.1% of patients on 1.8 mg achieved MASH resolution without fibrosis worsening at this timepoint, versus roughly 20% on placebo. Triglycerides, LDL, and blood pressure improvements start showing up on lab work. Weight loss continues on a near-linear path. Weeks 25 through 48: Full protocol duration from MOMENTUM. The 2.4 mg arm reached 15.6% total body weight loss at week 48 with the curve still trending downward. Body composition analysis confirmed 78.1% of that loss was fat mass. The IMPACT 48-week extension data showed statistically significant ELF score and liver stiffness improvements, which formed the basis for FDA Breakthrough Therapy Designation in January 2026. GI side effects are markedly lower than the early weeks by this stage; heart rate elevation of 2-3 bpm may persist at 2.4 mg.
GI side effects most pronounced (nausea, decreased appetite, constipation). Minimal weight change during adjustment. Optional 1.2 mg lead-in dose establishes tolerability before escalation.
No community data: science-only
Dose may increase to 1.8–2.4 mg. Measurable liver fat reduction begins (MASLD studies show significant LFC reduction within first 12 weeks). Early weight loss 3–5%. GI symptoms typically stabilize after week 8.
No community data
MASLD: 56–76% liver fat reduction by week 24. IMPACT: 59.1% MASH resolution (1.8 mg), 38.1% (1.2 mg) vs ~20% placebo. Triglycerides, LDL, and blood pressure improvements appear on labs. Weight loss continues at near-linear rate.
No community data
MOMENTUM: 15.6% body weight loss at 2.4 mg/48wk; trajectory still declining at week 48. 78.1% of total loss confirmed as fat mass. IMPACT 48wk: statistically significant ELF score + liver stiffness reduction; basis for FDA BTD Jan 2026.
No community data
Source: Estimated ~4-6 days based on weekly dosing schedule and EuPort albumin-binding domain; exact human t½ not publicly disclosed. Preclinical mouse MRT ~22h (Nestor et al., PMID 35461369)
Loading the interactive decay curve.
Pemvidutide (ALT-801) is an investigational drug with no FDA, EMA, or other regulatory approval for any indication. It received FDA Breakthrough Therapy Designation for MASH on January 5, 2026, which expedites the review process but does not constitute approval. All human data comes from Altimmune-sponsored clinical trials: MOMENTUM (obesity, Phase 2, NCT04944680) and IMPACT (MASH, Phase 2b). Phase 3 for MASH is planned to begin in 2026 following a successful end-of-Phase 2 FDA meeting. There is no legitimate consumer source. The lipidated EuPort domain synthesis is not feasible for research peptide manufacturers. Research-grade material from suppliers like MedChemExpress (catalog HY-P99852) is intended for in vitro and preclinical use only, priced at roughly $500-$2,000+ per milligram. Any product marketed as pemvidutide from a grey-market peptide vendor should be treated as mislabeled. For athletes: pemvidutide is not currently listed on the WADA Prohibited List by name, but GLP-1 receptor agonists as a class may fall under metabolic modulators depending on future WADA classification updates. This content is for informational purposes only and does not constitute medical advice. Consult a licensed healthcare provider before considering any investigational therapy.
Peptide Schedule Research TeamReviewed Apr 20268 Citations
