MEDICAL DISCLAIMER: Educational research guidelines only. Lyophilized peptides are investigational chemical compounds and are NOT approved for human consumption, diagnosis, or therapy. Consult a licensed physician before any research application.
MariTide Dosage Chart, Schedule & Reconstitution Protocol
Quickstart Highlights
MariTide (maridebart cafraglutide, formerly AMG 133) is an investigational Amgen antibody-peptide conjugate for obesity and type 2 diabetes. It pairs GLP-1 receptor agonism with GIP receptor antagonism: a monoclonal anti-GIPR antibody is conjugated to two GLP-1 agonist peptides (PMID 38316982). The antibody scaffold gives a ~21-day half-life, enabling subcutaneous dosing once every 4 weeks (monthly) rather than weekly. Trials used 140, 280, and 420 mg monthly, often with gradual dose escalation to limit nausea. In the Phase 2 trial, MariTide produced up to ~20% mean weight loss without diabetes and up to ~17% with type 2 diabetes (plus HbA1c reductions up to 2.2 points) at 52 weeks, with no plateau (PMID 40549887). It is administered subcutaneously by autoinjector; the single-vial reconstitution figures here are an educational measurement reference. MariTide is NOT FDA- or EMA-approved and is in Phase 3 MARITIME trials with a readout near early 2027.
Reconstitute: Add 1 mL bacteriostatic water → 420 mg/mL concentration.
Typical dose: 140-420 mg SC once every 4 weeks (monthly)
Easy measuring: At 420 mg/mL, 1 unit = 0.01 mL = 4.2 mg (4200 mcg) on a U-100 insulin syringe.
Storage: Antibody-peptide conjugate biologic: refrigerate at 2-8 °C, protect from light, and do NOT freeze (freezing can aggregate the antibody). Do not shake. The commercial investigational product is a refrigerated liquid in a prefilled autoinjector; for the educational lyophilized-vial model, keep the powder refrigerated, and after reconstitution store at 2-8 °C and use within about 2-4 weeks. Discard if the solution is cloudy or contains visible particulates.
Half-life: ~14-21 days (intact drug), roughly 3x semaglutide; supports once-monthly (every 4 weeks) subcutaneous dosing.
Route: Subcutaneous once every 4 weeks (monthly), clinically via prefilled autoinjector; modeled here as a high-concentration reconstitution reference for measurement only.
Status: Investigational; NOT FDA- or EMA-approved. In Phase 3 MARITIME trials (readout ~early 2027). Educational content, not medical advice.
About MariTide
MariTide (maridebart cafraglutide, formerly AMG 133) is an Amgen antibody-peptide conjugate that simultaneously activates the GLP-1 receptor and blocks the GIP receptor. Unlike most peptides catalogued on this site, its real-world clinical route genuinely is subcutaneous, delivered as a prefilled autoinjector once every four weeks; the vial-and-bacteriostatic-water scheme below is an educational reconstitution reference for measurement, not a commercially available format [1][2].\n\nThe defining feature of MariTide dosage is its monthly cadence. Because the antibody scaffold and reversible target binding extend the half-life to roughly 21 days, the molecule was engineered for once-monthly (or less frequent) dosing rather than the weekly schedule of semaglutide or tirzepatide [2][6]. The doses evaluated in trials are 140 mg, 280 mg, and 420 mg subcutaneously every 4 weeks, with optional gradual dose escalation to blunt early gastrointestinal effects [1][5].\n\nClinically, MariTide is a large mg-scale biologic, so its 280 mg and 420 mg doses are delivered as larger volumes (in practice, an autoinjector or split injections) rather than a single small insulin-syringe draw. The educational model here reconstitutes a 420 mg vial with 1 mL of bacteriostatic water to a 420 mg/mL reference solution, so on a U-100 insulin syringe 140 mg corresponds to about 33 units, 280 mg to about 67 units, and 420 mg to 100 units (1.0 mL).\n\nFrequency: Inject once every 4 weeks (monthly) subcutaneously into the abdomen, thigh, or upper arm; rotate sites and, where used, follow a deliberate multi-month dose-escalation schedule to improve tolerability [1][7].
Quick Protocol Navigation
Reconstitution Instruction & Mixing Step-by-Step
Lyophilized powder must be reconstituted carefully. Agitating peptide chains can shear disulfide bonds and render the peptide biologically inert.
Draw 1 mL of bacteriostatic water into a sterile syringe (this yields a 420 mg/mL reference solution from a 420 mg vial).
Inject the water slowly down the inner wall of the vial; do not spray it directly onto the lyophilized cake, and avoid foaming this antibody-based product.
Gently swirl or roll the vial until fully dissolved and clear — never shake, since agitation can shear and aggregate the antibody conjugate.
Load a U-100 insulin syringe to the units for your dose (140 mg ≈ 33 units / 0.33 mL, 280 mg ≈ 67 units / 0.67 mL, 420 mg = 100 units / 1.0 mL); higher doses may need more than one draw.
Swab the site (abdomen, thigh, or upper arm), inject subcutaneously once every 4 weeks, rotate sites, and return the vial to the refrigerator at 2-8 °C.
Interactive MariTide Syringe Calculator
Currently visualizing the 420 mg vial reconstituted with 1 mL bacteriostatic water. Adjust the target dose to dynamically render syringe units.
Reconstitution Calculation: 420mg dry powder in 1mL water yields 420.00 mg/mL. To evaluate a 250mcg dose, pull to 0.1 units (0 syringe ticks).
U-100 Syringe Representation
Educational reference visual. Assumes standard U-100 insulin syringe where 1.0 mL volume = 100 units.
Titration & Dose Escalation Schedules
| Phase | Dose per injection | Units (per injection) |
|---|---|---|
| Initiation — 140 mg once every 4 weeks (lowest studied monthly dose; ~33 units / 0.33 mL) | 140000 mcg (140 mg) | 33 units (0.33 mL) |
| Escalation — 280 mg once every 4 weeks (~67 units / 0.67 mL) | 280000 mcg (280 mg) | 67 units (0.67 mL) |
| Target / maintenance — 420 mg once every 4 weeks (~100 units / 1.0 mL) | 420000 mcg (420 mg) | 100 units (1.00 mL) |
Administration guidelines: Refer to guidelines | 1 mL Reconstitution
Research Supplies Quantity Planner
Scientific mathematical planning of syringes, bacteriostatic water and dry vials needed for extended research blocks using the 420 mg vial.
Peptide Vials (MariTide, 420 mg each):
- check8 weeks (2 monthly doses): up to ~840 mg ≈ 2 vials
- check12 weeks (3 monthly doses): up to ~1260 mg ≈ 3 vials
- check16 weeks (4 monthly doses): up to ~1680 mg ≈ 4 vials (one 420 mg vial per monthly injection)
Insulin Syringes (U-100):
- check8 weeks: ~4 syringes (1 to reconstitute + 1 to inject per monthly dose)
- check12 weeks: ~6 syringes
- check16 weeks: ~8 syringes (each ≤420 mg dose fits one 100-unit draw)
Bacteriostatic Water (10 mL bottles): Use 1 mL per vial for reconstitution.
- check8 weeks (2 vials): ~2 mL → 1 × 10 mL bottle
- check12 weeks (3 vials): ~3 mL → 1 × 10 mL bottle
- check16 weeks (4 vials): ~4 mL → 1 × 10 mL bottle
Alcohol Swabs: One for the vial stopper + one for the injection site each dose.
- checkPer monthly dose: ~2-3 swabs (stopper at reconstitution + stopper + injection site)
- check8-12 weeks: ~6-9 swabs → 1 × 100-count box
- check16 weeks: ~8-12 swabs → 1 × 100-count box
Mechanism of Action (MOA)
MariTide (maridebart cafraglutide) is a bispecific antibody-peptide conjugate. Its scaffold is a fully human monoclonal IgG antibody that acts as an antagonist at the glucose-dependent insulinotropic polypeptide receptor (GIPR, in vitro human IC50 ~42 nM), to which two GLP-1 receptor agonist peptide analogues are chemically conjugated through amino-acid linkers (in vitro human GLP-1R EC50 ~24 pM) [2][3]. This combines two mechanisms in one molecule: potent, sustained GLP-1R agonism and simultaneous GIPR blockade.\n\nGLP-1 receptor agonism drives the therapeutic core. At pancreatic beta cells it stimulates glucose-dependent insulin secretion and suppresses glucagon, lowering blood glucose with low intrinsic hypoglycemia risk; in the gut it slows gastric emptying; and in the hypothalamus and brainstem it activates anorexigenic pathways that reduce hunger and energy intake [1][3]. The GIPR-antagonist arm is the more novel and debated component: paradoxically, both GIPR agonism (as in tirzepatide) and GIPR antagonism (as in MariTide) can augment GLP-1-driven weight loss in humans, and Amgen's preclinical and clinical data indicate that blocking GIPR alongside GLP-1R agonism produces robust, durable fat loss with improved metabolic parameters [2][3].\n\nPharmacokinetically, the antibody architecture is what sets MariTide apart. The conjugate is absorbed slowly after subcutaneous injection and cleared slowly, giving intact-drug mean terminal half-life estimates of roughly 14-21 days across the Phase 1 single- and multiple-ascending-dose study — about three times the ~7-day half-life of semaglutide [2][3]. That long exposure is the basis for once-every-4-weeks (monthly) dosing, and the durability is striking: in Phase 1, three monthly 420 mg doses produced about 14.5% mean weight loss by day 85 that was largely maintained (~11.2%) out to day 150, months after the last dose [2][3][4].\n\nThe dosing strategy is deliberately stepwise. The Phase 2 trial tested fixed monthly doses of 140, 280, and 420 mg, plus dose-escalation arms that ramp to the 420 mg target over several months; the Phase 3 MARITIME program uses an optimized low-dose initiation (for example, starting near 21 mg and stepping through 35 mg and 70 mg before reaching target) over an 8-week escalation to further reduce early nausea and vomiting [1][5][8]. Gastrointestinal adverse events were predominantly mild-to-moderate, transient, and concentrated around the first dose, with lower incidence in the escalation arms [1][7].\n\nClinically MariTide is given as a subcutaneous autoinjector once monthly; the high-concentration single-vial reconstitution modeled here (420 mg in 1 mL) is an educational simplification so the mg-scale doses map onto U-100 insulin-syringe units, not the real formulation [1].
Clinical Trial Efficacy Highlights
- starPhase 2 obesity trial (Jastreboff AM, Ryan DH, Bays HE, et al., N Engl J Med 2025): in 592 adults randomized across cohorts with and without type 2 diabetes, once-monthly MariTide produced mean body-weight reductions up to approximately 20% (efficacy estimand near −19.9%) in participants with obesity but without diabetes versus about −2.5% with placebo at 52 weeks, with no apparent plateau in the weight-loss curve [1].
- starIn the same Phase 2 trial, participants with obesity AND type 2 diabetes achieved up to roughly 17% mean weight loss together with HbA1c reductions of up to 2.2 percentage points, alongside improvements in cardiometabolic risk factors, supporting a dual metabolic indication [1][7].
- starPhase 1 first-in-human study (Véniant MM, Lu SC, Atangan L, et al., Nat Metab 2024): in adults with obesity, three once-every-4-weeks doses of 420 mg produced about −14.5% mean body-weight change by day 85, and the effect was largely sustained at about −11.2% through day 150 — roughly two months after the final dose — demonstrating unusual durability for the molecule [2][3].
- starThe Phase 1 multiple-ascending-dose data showed dose-dependent weight loss across the 140, 280, and 420 mg monthly arms (for example roughly −7.4% at the 140 mg level by day 78), establishing the 140/280/420 mg monthly dose range later carried into Phase 2 [2][3].
- starPharmacokinetic characterization in Phase 1 confirmed a long intact-drug half-life on the order of 14-21 days, about three times that of weekly semaglutide, which is the mechanistic basis for monthly (or less frequent) subcutaneous dosing [2][3].
- starPreclinical work in the same Nature Metabolism report showed that conjugating a GIPR-antagonist antibody to GLP-1 analogues drove greater and more durable weight loss with improved metabolic parameters in obese mice and monkeys than GLP-1 agonism alone, validating the bispecific design that underlies MariTide [2].
- starDose-escalation arms in the Phase 2 study reduced the incidence of gastrointestinal adverse events relative to starting directly at high fixed doses, informing the optimized low-dose-initiation escalation now used in the Phase 3 MARITIME program [1][7][8].
- starAs of 2025-2026 MariTide is being evaluated in the Phase 3 MARITIME chronic weight-management trials (72-week studies in obesity/overweight with and without type 2 diabetes); these are ongoing with a primary readout anticipated around early 2027, so no Phase 3 efficacy or long-term outcome data are yet available [8].
Side Effects & Tolerability Profile
Clinical subjects transiently report mild side effects. Slowly escalating the titration dose represents the single most effective intervention to limit side effects.
- warningGastrointestinal effects are the most common adverse events: nausea, vomiting, and constipation predominated in the Phase 1 and Phase 2 trials. They were mostly mild-to-moderate, transient, and concentrated around the first dose, and resolved relatively quickly [1][2][7].
- warningGradual dose escalation markedly lowers gastrointestinal toxicity: arms that ramped to the 420 mg target over several months had fewer and milder GI events than those starting at a high fixed dose, which is why the Phase 3 program uses a multi-week low-dose initiation [1][7][8].
- warningTreatment discontinuation for adverse events was roughly 11% in the Phase 2 trial, with GI-related discontinuations under about 8% — higher than placebo but consistent with the incretin drug class [1][7].
- warningAs a GLP-1 receptor agonist, MariTide carries class-level cautions shared with semaglutide, liraglutide, and tirzepatide, including potential acute pancreatitis, gallbladder events (cholelithiasis/cholecystitis) with rapid weight loss, and increased hypoglycemia risk when combined with insulin or sulfonylureas; these require clinician oversight in trial settings [1].
- warningInjection-site reactions and a modest increase in heart rate can occur with this drug class; rapid GI fluid losses can contribute to dehydration and, rarely, acute kidney injury [1].
- warningLong-term safety, effects on lean mass and bone mineral density, cardiovascular outcomes, and use in pregnancy, breastfeeding, or children have not been established; these are being assessed in the ongoing Phase 3 MARITIME program [8].
- warningBecause MariTide is an investigational biologic and not commercially available, any research-grade material sold under this name cannot be assumed sterile, correctly sequenced, or accurately dosed; the antibody conjugate is also sensitive to freezing and agitation.
- warningRegulatory status: MariTide is NOT approved by the FDA, EMA, or any major regulator for any indication. It is an investigational drug in clinical development; the dosing and reconstitution figures here are educational only and are not medical advice.
Subcutaneous Injection Technique
Most research peptides require subcutaneous injection into fatty tissue. Never inject directly into a blood vessel or deep muscle tissue unless clinically detailed.
1. Site Selection
Common locations include the abdomen (2 inches from navel), outer upper arms, or thighs.
2. Sanitization
Thoroughly clean the selected site, stopper and vial top using 70% isopropyl alcohol prep swabs.
3. Angle & Push
Pinch the skin and insert the needle at a 45 to 90-degree angle. Depress plunger smoothly.
4. Site Rotation
Rotate injection sites continuously to avoid lipodystrophy or tissue scarring.
Frequently Asked Questions
What is the typical MariTide dosage?expand_more
In clinical trials the typical MariTide dosage is 140 mg, 280 mg, or 420 mg given subcutaneously once every 4 weeks (monthly). The 420 mg monthly dose is the highest target studied and produced the greatest weight loss. To reduce early nausea and vomiting, trials often escalate gradually to the target dose over several months rather than starting high; the Phase 3 MARITIME program uses a low-dose initiation (for example around 21 mg, then 35 mg, then 70 mg) over an 8-week ramp before reaching target. MariTide is investigational, so these are research doses, not a prescribed regimen.
Is MariTide FDA approved?expand_more
No. MariTide (maridebart cafraglutide, AMG 133) is NOT approved by the FDA or the EMA for any indication. As of 2025-2026 it is an investigational drug being evaluated in Amgen's Phase 3 MARITIME chronic weight-management trials, with a primary readout anticipated around early 2027. It is not commercially available; any material sold under this name is unapproved, and the information here is educational only, not medical advice.
What is the half-life of MariTide?expand_more
MariTide has an unusually long half-life because it is built on a monoclonal antibody scaffold. Phase 1 data estimated an intact-drug mean terminal half-life of roughly 14-21 days — about three times that of weekly semaglutide (~7 days). This long exposure is exactly what allows once-every-4-weeks (monthly) subcutaneous dosing, and in Phase 1 weight loss was largely maintained for two months after the final dose.
How is MariTide administered and can the dose be reconstituted?expand_more
Clinically MariTide is a subcutaneous injection given once every 4 weeks, in trials via a prefilled autoinjector. Because it is a large mg-scale antibody-peptide conjugate, the 280 mg and 420 mg doses are larger-volume injections rather than a single small insulin-syringe draw. The reconstitution model on this page is an educational reference only: dissolving a 420 mg vial in 1 mL of bacteriostatic water gives a 420 mg/mL solution, so 140 mg is about 33 units, 280 mg about 67 units, and 420 mg is 100 units (1.0 mL) on a U-100 syringe. Swirl gently, never shake, and keep refrigerated.
How does MariTide differ from semaglutide and tirzepatide?expand_more
MariTide is a GLP-1 receptor agonist combined with a GIP receptor ANTAGONIST, delivered as an antibody-peptide conjugate dosed monthly. Semaglutide is a pure GLP-1 agonist and tirzepatide is a GLP-1/GIP dual AGONIST, both dosed weekly. Notably, both blocking GIPR (MariTide) and activating GIPR (tirzepatide) can enhance GLP-1-driven weight loss. The biggest practical difference is cadence: MariTide's ~21-day half-life enables once-monthly injection versus the weekly schedule of semaglutide and tirzepatide.
Related Guides & Tools
Step-by-step references for reconstituting, measuring, and storing MariTide, plus the universal dosing calculator.
Academic References & Study Citations
Jastreboff AM, Ryan DH, Bays HE, et al. Once-Monthly Maridebart Cafraglutide for the Treatment of Obesity — A Phase 2 Trial. N Engl J Med. 2025;393(9):843-857. doi:10.1056/NEJMoa2504214. PMID 40549887. (Up to ~20% weight loss without diabetes, ~17% with type 2 diabetes at 52 weeks; 140/280/420 mg every 4 weeks.) View Scientific Paper →
Véniant MM, Lu SC, Atangan L, et al. A GIPR antagonist conjugated to GLP-1 analogues promotes weight loss with improved metabolic parameters in preclinical and phase 1 settings. Nat Metab. 2024;6(2):290-303. PMID 38316982. (AMG 133 mechanism, ~21-day half-life, Phase 1 weight loss.) View Scientific Paper →
Véniant MM, et al. A GIPR antagonist conjugated to GLP-1 analogues... Nat Metab. 2024;6(2):290-303 — full text (PMC). Reports GIPR IC50 ~42 nM, GLP-1R EC50 ~24 pM, intact-drug half-life 14-21 days, and durable weight loss to day 150. View Scientific Paper →
ClinicalTrials.gov. Single and Multiple Ascending Dose Study of AMG 133 in Participants With Obesity (Phase 1). NCT04478708. U.S. National Library of Medicine. View Scientific Paper →
ClinicalTrials.gov. A Study to Evaluate the Efficacy, Safety, and Tolerability of Maridebart Cafraglutide (AMG 133) in Adults With Obesity (Phase 2). NCT05669599. U.S. National Library of Medicine. View Scientific Paper →
Amgen. Amgen Announces Robust Weight Loss With MariTide in People Living With Obesity or Overweight at 52 Weeks in a Phase 2 Study. Press release, November 2024. View Scientific Paper →
Amgen. Results From Amgen's Phase 2 Obesity Study of Monthly MariTide Presented at the American Diabetes Association 85th Scientific Sessions. Press release, June 2025. View Scientific Paper →
Amgen. Inside Amgen's Phase 3 MARITIME Program: Advancing the Future of Obesity Care. June 2025. (72-week Phase 3 studies, optimized low-dose initiation, readout ~early 2027.) View Scientific Paper →