PF-08653945 (MET-233i)_Dosage, benefits & legal status
Also known as MET-233i, MET-233, PF'3945
An experimental amylin shot designed for monthly dosing, now in a 940-person phase 2b.
Common vial size is what vendors typically sell, not a recommendation. Enter your own vial in the calculator.
What is PF-08653945 (MET-233i)?
Plain language first. The technical label stays, but it never stands alone.Overview
Amylin is the fullness hormone released alongside insulin, and this version lasts weeks rather than minutes. An 80-person phase 1 showed up to 8.4% placebo-adjusted weight loss after five weekly doses, and the 940-person SOLIS-1 phase 2b is under way. It is not approved anywhere and has no INN.
PF-08653945 is an amylin analogue that also activates the calcitonin receptor. Metsera developed it as MET-233i, and Pfizer has owned it since November 2025. It carries the same albumin-binding lipid platform as berobenatide, and the two are designed to be given together.
What it's used for
An experimental amylin shot for weight loss, alone or with Pfizer's GLP-1 berobenatide. Only phase 1 results exist: 8.4% placebo-adjusted loss at day 36 on the top dose.
How does PF-08653945 (MET-233i) work?
What it does in the body, and where.PF-08653945 is a lipidated copy of amylin, redesigned to resist clumping into fibrils and to last for weeks.
- 01Amylin receptorAmylin receptors in the brainstem signal fullness and slow stomach emptying. Metsera reports full agonist activity, with cAMP potency at the AMY3 receptor about four times that of pramlintide.
- 02Calcitonin receptorIt also activates the calcitonin receptor, making it a dual amylin and calcitonin agonist. Its trial record uses the class label DACRA.
- 03Albumin anchorMetsera's HALO lipid binds albumin. A single dose took about 19 days to fall to half its peak level, and multiple-dose exposure tracked berobenatide's, so the two can share a schedule.
Hits 2 receptors at once.
What else is it used for?
Each group carries its own evidence level.Approved means regulators have cleared it for that purpose. Investigational means it is in trials. Early research means it is being studied and is not established.
Phase 1
Investigational- Human trialFive weekly doses, 40 people: placebo-subtracted weight loss of 8.4% at day 36 on 1.2 mg. The placebo group changed 0.6%.
- Human trialSingle doses, 40 people: 5.3% placebo-subtracted loss by day 8 after 2.4 mg.
- No dataWeight results for the lower doses sit in image tables in the filing and were not readable for this page.
Animal work
Early research- Animal studyIn rats, single doses of 3 and 10 nmol/kg caused more weight loss by day 6 than cagrilintide at 10 nmol/kg.
- Animal studyIn rats, the combination with berobenatide beat cagrilintide plus semaglutide from day 2. These are company figures without published percentages.
Combination with berobenatide
Investigational- No dataNo clinical results for the combination have been released. The phase 1/2a and SOLIS-1 are both still running.
The '19-day half-life' is the time a single dose took to fall to half its peak level, not a terminal elimination half-life; that has not been published. The 8.4% weight loss is placebo-adjusted, from 8 people on the top weekly dose at day 36 after five weekly doses, not one monthly dose. 'Placebo-like tolerability' applies only to starting doses: all 8 people on 1.2 mg weekly had nausea. No combination data with berobenatide have been released. It has no INN, so do not assume batelintide or lenbelintide are this compound. PF-08653944, one digit different, is berobenatide.
The published record
Papers and trials about PF-08653945 (MET-233i)
6 papers tagged human · 0 not reviews or lab · 0 clinical trial publications
4 registered trials · none with posted results
Furthest stage reached: Phase 2, under way
Counted from Europe PMC indexing, not read by a person; a human tag can land on reviews, commentary or lab papers; clinical trial publications is the narrower count.
At a glance
Four things to know about PF-08653945 (MET-233i)
Evidence
Investigational
Category
Weight loss and metabolic
Common vial
Varies
Half-life
Not published (about 19 days to fall to half of peak)
How much, and do you cycle it?
The range, and whether you take breaks.0.15 up to 1.2 mg weekly (phase 1 doses), weekly; monthly dosing under test. Not cycled in the trials Trial dose
Given weekly, or weekly then monthly, with no planned break. SOLIS-1 runs 48 weeks to its primary endpoint.
How long does it stay in the body?
The half-life, and where the figure comes from.Not published (about 19 days to fall to half of peak)Trial protocol
The company defines its 19-day figure as the time from dosing to 50% of the peak concentration after a single dose, not the usual terminal half-life. The terminal half-life is a registered outcome of NCT07022977, and no results have been posted. Multiple-dose exposure was similar to berobenatide's. In pigs: 114 hours.
Source: Metsera, Form 8-K (9 June 2025)
You can compare this against the whole library to see where it sits.
How do I dose and price it?
Enter your vial and your dose. Pick a mix. We show the draw and the cost.The vial holds a fixed amount of drug. Adding more water does not make more drug, it just spreads it thinner, so you draw a bigger number on the syringe for the same dose.
Choose your mix
Measuring the water1 mL = one full 100-unit syringe.
How do you store it?
Before mixing, and after.Dry powder in the freezer or fridge. Once mixed, fridge, and use within about a month.
Unmixed lyophilized PF-08653945 (MET-233i) keeps for a long time cold. Once you add water the clock starts: most reconstituted vials hold up for roughly 28 to 30 days at fridge temperature. Keep it out of light, and do not freeze it after mixing.
What are the side effects and cautions?
Known cautions and warnings for this compound.Who should avoid it
- Diabetes, excluded from the monotherapy phase 1 and from SOLIS-1
- Pregnancy or breastfeeding
- Anyone wanting known long-term safety: published results cover at most five weekly doses
Stop and get help
- Vomiting badly enough that you cannot keep fluids down
- Severe stomach pain spreading to your back
- Spreading hives, swelling of the face or throat, or trouble breathing
Common effects
- Nausea in all 8 people on 1.2 mg weekly and all 6 given a single 2.4 mg dose
- Vomiting in 5 of 6 at 2.4 mg, and 3 of 8 at both 0.6 and 1.2 mg weekly
- Few and mild stomach effects at 0.15 to 0.3 mg
- No severe events in phase 1; stomach effects mostly came in the first week
Where this page says nothing is established, that means nobody has studied it, not that a compound is safe.
Is PF-08653945 (MET-233i) approved?
And where the numbers on this page come from.No. PF-08653945 (MET-233i) is not approved anywhere and is currently in company-run clinical trials. There is no legal route to obtain it outside a trial.
- Approval statusInvestigational
- RouteUnder the skin (subcutaneous)
- Checked11 October 2026
- DoseFrom published clinical trials. Not approved by a regulator for this dose.
- Vial sizeFrom what vendors typically list; not a recommendation.
- SourcesMetsera, Form 8-K with phase 1 results (9 Jun 2025)Metsera, Form 10-K for 2024ClinicalTrials.gov, SOLIS-1 (NCT07575932)ClinicalTrials.gov, phase 1 monotherapy (NCT07022977)ClinicalTrials.gov, combination with berobenatide (NCT06924320)Pfizer, ADA 2026 release (6 Jun 2026)Pfizer, Form 10-Q for Q2 2026
What has happened recently
Not approved anywhere and has no INN. The IND was cleared in October 2024. The monotherapy phase 1 (NCT07022977, 144 people) finished in April 2026; results for its first 80 participants appeared in a June 2025 company filing. A phase 1/2a combining it with berobenatide (NCT06924320) is recruiting, and SOLIS-1 (NCT07575932), a 940-person phase 2b of weekly and monthly dosing alone and with berobenatide, started in May 2026 and has finished enrolling. Pfizer acquired it with Metsera in November 2025; part of the deal's contingent payment depends on the combination reaching phase 3 and approval.
You can compare this against the whole library, or read how to check a seller.
What else is like PF-08653945 (MET-233i)?
Others in Amylin analogs, side by side.If you're weighing PF-08653945 (MET-233i), it's worth reading Pramlintide, Cagrilintide, and Eloralintide in the same class.
An experimental amylin shot designed for monthly dosing, now in a 940-person phase 2b.
- Dose
- 0.15 up to 1.2 mg weekly (phase 1 doses)
- How often
- Weekly; monthly dosing under test
An approved mealtime shot used with insulin to blunt blood-sugar spikes and hunger.
- Dose
- 0.015 up to 0.12 mg per dose (start low, increase slowly)
- How often
- With meals
A weekly fullness-hormone shot, often paired with semaglutide for bigger loss.
- Dose
- 0.3 up to 4.5 mg per dose (start low, increase slowly)
- How often
- Weekly
An experimental weekly fullness-hormone shot for weight loss.
- Dose
- 1 up to 9 mg per week (trial doses)
- How often
- Weekly
Guides for this compound
- How to Reconstitute a Peptide
Mix peptide powder with bacteriostatic water, step by step.
- How to Read an Insulin Syringe
Read the units, convert to millilitres, and draw the exact dose.
- mcg vs mg: The Peptide Dosing Mistake to Avoid
Your vial says mg and your protocol says mcg. Here is the conversion and how to check it.
- How to Read a Peptide COA
What the purity number does and does not tell you, and how to spot an edited report.
- How to Vet a Peptide Vendor
Independent COAs, HPLC purity, and the red flags that mean walk away.
Sources
- Metsera, Form 8-K with phase 1 results (9 Jun 2025)(2025)Single doses of 0.15 to 2.4 mg (40 people) and five weekly doses of 0.15 to 1.2 mg (40 people). Placebo-subtracted weight loss 5.3% at day 8 after 2.4 mg and 8.4% at day 36 on 1.2 mg weekly. About 19 days from dosing to 50% of peak concentration. Full adverse event tables.
- Metsera, Form 10-K for 2024(2025)Ultra-long-acting amylin analogue with improved solubility, designed to lower fibril formation; dual amylin and calcitonin receptor agonist. Rat weight loss beat cagrilintide. Pig half-life 114 hours. IND cleared October 2024.
- ClinicalTrials.gov, SOLIS-1 (NCT07575932)(2026)Phase 2b, 940 enrolled, alone or with berobenatide against placebo. Primary endpoint % weight change at week 48. Started 11 May 2026; diabetes excluded.
- ClinicalTrials.gov, phase 1 monotherapy (NCT07022977)(2026)144 enrolled in four parts, including 12 weekly doses followed by monthly doses. Completed April 2026; no results posted.
- ClinicalTrials.gov, combination with berobenatide (NCT06924320)(2026)Phase 1/2a, about 381 participants, weekly and every-4-week dosing of both drugs together. Recruiting.
- Pfizer, ADA 2026 release (6 Jun 2026)(2026)SOLIS-1 investigates weekly and monthly maintenance dosing of PF'3945 alone and with berobenatide.
- Pfizer, Form 10-Q for Q2 2026(2026)Contingent value right payments tied to the combination: $4.60 a share at its phase 3 start and $9.65 at FDA approval.
Beyond these, 6 records are indexed. Browse the records