Gastrointestinal

Apraglutide

Also called FE 203799, FE203799

Apraglutide is an experimental, long-acting copy of the gut hormone GLP-2, given as a once-weekly shot. Ironwood Pharmaceuticals is testing it for adults with short bowel syndrome who depend on IV nutrition or fluids. Its first phase 3 trial (STARS) met its main goal, but in 2025 Ironwood said that, after talks with the FDA, a second, confirmatory phase 3 trial was needed. That trial (STARS-2) began in mid-2026, so apraglutide is not approved anywhere.

Late-stage trialsTested in large human trials (phase 2b/3) but not yet approved in the US.

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Illustrative chain. The exact sequence has not been published in a source we could verify.

Overview

How it works

Established for the GLP-2 class: apraglutide is a full agonist of the GLP-2 receptor, with lab potency and selectivity similar to natural GLP-2 ²¹². GLP-2 receptor activation helps the remaining intestine adapt and absorb more fluid and nutrients ¹. Its main difference is how long it lasts: in rats its half-life was about 159 minutes vs 6.4 minutes for natural GLP-2 and 19 minutes for teduglutide (animal data) ⁷, and its reported elimination half-life is about 72 hours, which allows once-weekly dosing ⁴.

What research shows

STARS (phase 3 human RCT, n=163 adults with short bowel syndrome and intestinal failure, once weekly vs placebo): weekly IV support volume fell 25.5% vs 12.5% at 24 weeks (P=.001); in patients with a stoma it fell 25.6% vs 7.8% (P<.001). 43.0% vs 27.5% gained at least one IV-free day per week ¹.
In STARS patients whose colon was still connected, 48-week goals were not met: 51.8% vs 44.4% gained an IV-free day, and 12.5% vs 7.4% came off IV support entirely (neither statistically significant) ¹³.
Ironwood later reported that the drug exposure and dose delivered in STARS were lower than planned, which it linked to how doses were prepared and given; after FDA feedback it said a confirmatory trial was needed (company statement) ⁹.
Phase 2 crossover trial (human, n=8): once-weekly 5 mg and 10 mg raised urine output by about 714 and 795 mL/day vs placebo, a sign of better fluid absorption ⁴.
Phase 2 open-label study (human, n=9, colon-in-continuity, 52 weeks): IV support volume fell 52% (4,702 mL/week) and 7 of 9 patients gained at least one IV-free day ⁶.
Rat, monkey and minipig studies (animal): apraglutide lasted much longer than natural GLP-2, teduglutide or glepaglutide in rats and caused more small-intestine growth with less frequent dosing ⁷.

Doses studied in people

Study or label	Dose used	Source
Phase 2 crossover RCT (n=8)	5 mg once weekly vs placebo for 4 weeks, then 10 mg once weekly for 4 weeks, subcutaneous	⁴
Phase 1/2 open-label metabolic balance trial (n=8)	5 mg once weekly, subcutaneous, for 4 weeks	⁵
Phase 1 renal impairment study (n=16)	Single 5 mg subcutaneous dose	⁸

Doses shown come from published trials only and are reported, not recommended. The STARS phase 3 dose is not listed because neither the published abstract nor the trial registry states it; Ironwood has said the dose actually delivered in STARS was lower than planned ⁹.

Read this first: these are the amounts given to participants in published studies or written on official prescribing labels, reported for reference. They are not recommendations. Trial doses were chosen for specific patients under medical supervision, and a dose that is safe in one person can be harmful in another.

Vial math

Many research vials hold 5 or 10 mg of powder. This table shows how much ends up in each mark on a U-100 insulin syringe for common amounts of added liquid. It is arithmetic only, not a dose.

Vial	Liquid added	Concentration	Per unit (0.01 mL)
5 mg	1 mL	5 mg/mL	50 mcg	Open in calculator
5 mg	2 mL	2.5 mg/mL	25 mcg	Open in calculator
5 mg	3 mL	1.67 mg/mL	16.7 mcg	Open in calculator
10 mg	1 mL	10 mg/mL	100 mcg	Open in calculator
10 mg	2 mL	5 mg/mL	50 mcg	Open in calculator
10 mg	3 mL	3.33 mg/mL	33.3 mcg	Open in calculator

More sizes: all vial sizes · How this works: Syringes and units · Reconstitution guide.

Safety

STARS (n=163): the published report describes apraglutide as well tolerated with a favorable safety profile, but the abstract and the company's topline release give no adverse-event rates ¹³.
Phase 2 crossover (n=8): common treatment-related effects were more urine, stoma complications and changes in stoma output, less thirst, swelling and injection-site reactions; no serious events were judged related to the drug ⁴.
Phase 1/2 open-label (n=8): common related effects included reduced stoma output, stoma complications, nausea, flatulence and abdominal pain; one patient had a related serious event (abdominal pain) ⁵.
Phase 2 colon-in-continuity study (n=9): 127 adverse events over 52 weeks, mostly mild to moderate ⁶.
People with severe kidney disease did not have higher drug levels after a single 5 mg dose ⁸.
Long-term safety is unknown; apraglutide has no approved label and the confirmatory trial is ongoing ¹¹¹².

Report side effects of any drug or product to the FDA through MedWatch. For a possible poisoning in the US, call Poison Control at 1-800-222-1222.

Legal status

FDA: Investigational; not FDA-approved. In April 2025 Ironwood said that FDA feedback indicated a confirmatory phase 3 trial is needed to seek approval ⁹. Ironwood aligned with the FDA on key trial design points in Q4 2025 ¹⁰. The confirmatory STARS-2 trial (about 124 patients, 24 weeks, once weekly vs placebo) was recruiting as of August 2026, with primary completion estimated for October 2028 ¹¹¹².
Compounding: No compounding-specific FDA action for apraglutide was found in the sources reviewed; it is an unapproved investigational drug.
Sports (WADA): Not named on the WADA 2026 Prohibited List. The S0 class bans drugs in clinical development with no approval from any government health authority, which appears to cover apraglutide; athletes should check with their anti-doping organisation ¹⁶.
Other: Not approved in any country. Asahi Kasei holds an exclusive license for Japan under a 2022 agreement with VectivBio ¹⁵.

Rules change often. See Legal status of peptides for how these categories work.

History

Early trials ran under the code FE 203799, sponsored by GlyPharma Therapeutics with VectivBio as collaborator ¹⁴; VectivBio pays royalties on it to Ferring under a license ¹⁵. Ironwood Pharmaceuticals took control of VectivBio in 2023 and completed the merger on December 12, 2023 ¹³. The phase 3 STARS trial ran from 2021 to 2024 and reported positive topline results on February 29, 2024 ²³. In April 2025, while preparing a US filing, Ironwood reported that drug exposure in STARS was lower than planned and that, after discussions with the FDA, a confirmatory phase 3 trial was needed to seek approval ⁹. Ironwood agreed key trial design points with the FDA in late 2025 ¹⁰, and the confirmatory STARS-2 trial was recruiting by August 2026 ¹¹¹².

Common questions

Is apraglutide approved?

No. It is not approved in any country. In 2025 Ironwood said FDA feedback showed a confirmatory phase 3 trial was needed, and that trial (STARS-2) began recruiting in 2026 ⁹¹¹¹².

Why does the FDA want another trial?

While preparing its filing, Ironwood found that the drug exposure and dose delivered in the STARS trial were lower than planned, and that FDA feedback indicated a confirmatory phase 3 trial is needed to seek approval ⁹.

What did the STARS trial show?

In 163 patients, once-weekly apraglutide cut weekly IV nutrition and fluid volume by 25.5% vs 12.5% on placebo at 24 weeks. Results at 48 weeks in patients with an intact colon were not statistically significant ¹.

How is it different from teduglutide?

Teduglutide is injected daily. Apraglutide lasts much longer in the body (a reported elimination half-life of about 72 hours), so it is being tested as a once-weekly shot ⁴⁷.

What are the known side effects?

Small trials reported stoma changes, more urine, swelling, nausea, abdominal pain and injection-site reactions, mostly mild to moderate ⁴⁵⁶. The STARS paper calls it well tolerated, but long-term safety is not yet known ¹.

Is apraglutide banned in sport?

It is not named on the 2026 WADA list, but the S0 class bans unapproved drugs still in clinical development, which appears to apply ¹⁶.

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Sources

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Last reviewed 2026-10-30 · How we research · Found an error? See our corrections policy.