Retatrutide has not been studied as a tablet. The ClinicalTrials.gov registry lists 34 studies of retatrutide, and in none of them was it given by mouth. The clinical trials used a subcutaneous injection once a week, and one phase 1 study also tested intravenous use. It was the injection that produced the results that drew attention to this molecule: 24.2 percent lower body weight after 48 weeks and 25.0 percent after 80 weeks. Below we explain why retatrutide comes as an injection and what this means when choosing a product.
In what form has retatrutide been studied?
We checked all retatrutide studies in the ClinicalTrials.gov registry as of 17 October 2026. The registry holds 34 studies: 15 in phase 1, 4 in phase 2 and 14 in phase 3, plus a pre-approval access programme.
| Route | Number of studies |
|---|---|
| subcutaneous injection | almost all |
| intravenous infusion | 1, part of a phase 1 study |
| tablet or capsule | 0 |
In the study descriptions, oral medicines appear only as comparison drugs. This is the case in interaction studies, where participants swallowed, for example, metoprolol or caffeine and received retatrutide as an injection.
Why is retatrutide given once a week?
Retatrutide is a single peptide that activates three receptors: GLP-1, GIP and glucagon. It was described by a team at Eli Lilly in 2022. Already the first study in humans showed that the way it is processed in the body allows once-weekly dosing, and the drop in body weight after one dose lasted up to day 43.
A phase 1b study in 72 people with type 2 diabetes measured the half-life at about 6 days. After 6 days half of the molecule is still in the blood, and the level is enough until the next dose. An injection once a week means 52 injections a year instead of daily intake. How long other peptides stay in the body is explained in the guide how long peptides stay in the body.
Why do peptides work poorly as tablets?
Peptides are poorly absorbed from the digestive tract. This is clearly seen with semaglutide, which as one of the medicines in this group also exists as a tablet. The tablet contains an additive called SNAC that makes absorption easier, and still only about 1 percent of the dose reaches the blood.
| Semaglutide | Reaches the blood | Dose |
|---|---|---|
| tablet | about 1 percent | 25 or 50 mg daily |
| subcutaneous injection | about 89 percent | 2.4 mg once a week |
In a study of 5 and 10 mg tablets 0.8 percent of the dose was absorbed, and only under strict rules: on an empty stomach, with little water and with a wait before eating. A 25 mg tablet uses about 73 times more semaglutide per week than a 2.4 mg injection. Both forms are compared in the guide semaglutide tablets vs injections.
Retatrutide is also a peptide, so a tablet would require its own formulation and its own studies. There are no such studies in the registry. All the results we know concern the injection.
What did retatrutide achieve as an injection?
In a phase 2 study in 338 people with obesity, retatrutide was injected under the skin once a week for 48 weeks. The 12 mg dose lowered body weight by an average of 24.2 percent, against 2.1 percent with placebo. In the phase 3 TRIUMPH-1 study in 2339 people the drop after 80 weeks was 25.0 percent at the 12 mg dose.
| Study | Duration | 12 mg dose | Placebo |
|---|---|---|---|
| phase 2 | 48 weeks | -24.2 percent | -2.1 percent |
| TRIUMPH-1 | 80 weeks | -25.0 percent | -3.9 percent |
How body weight fell month by month is described in the guide retatrutide results after one month, 3 months and a year. The results of each dose are collected in the guide retatrutide doses in trials.
Where is the retatrutide injection given?
The clinical trials describe a subcutaneous injection. One phase 1 study in healthy people with a high BMI compared three injection sites: the abdomen, the upper arm and the thigh. The researchers measured how much retatrutide reaches the blood from the arm and the thigh compared with the abdomen, and how quickly the body clears it.
In the registry the study has the status completed. The general rules of the different routes for peptides are described in the guide peptide routes of administration.
Vial or pen with retatrutide?
In the shop retatrutide comes in two injectable forms: as a powder in a vial and as a ready solution in a pen.
| Product | Form | Price | Availability |
|---|---|---|---|
| Retatrutide 20 mg Bio-Peptide | powder vial | 200 EUR | in stock |
| Retatrutide 20 mg Genheal | powder vial | 200 EUR | on backorder |
| Retatrutide 40 mg Nouveaux Ltd. Quick Pen | pen with solution | 350 EUR | in stock |
The vial has to be dissolved first, while the pen is ready straight away. The 40 mg pen contains twice as much substance as a vial and costs less than two vials. How many weeks each form lasts is calculated in the guide how long a GLP-1 vial lasts, and the convenience of both forms is compared in the guide peptide pen vs powder vial.
All variants are gathered on the retatrutide page. Retatrutide is not yet a registered medicine, and since June 2026 the registry has listed a pre-approval access programme. The products in the shop are material for laboratory research, not a medicine.
Frequently asked questions
Is retatrutide available as a tablet?
No. In none of the 34 studies registered on ClinicalTrials.gov was retatrutide given by mouth. The clinical trials concern a subcutaneous injection once a week.
How often is retatrutide given?
Once a week. The half-life of retatrutide is about 6 days, which according to the phase 1b study allows dosing once a week.
Why do peptides work poorly as tablets?
They are poorly absorbed from the digestive tract. From a semaglutide tablet about 1 percent of the dose reaches the blood, and from an injection about 89 percent.
How much weight was lost with retatrutide injections?
At the 12 mg dose an average of 24.2 percent of body weight after 48 weeks in the phase 2 study and 25.0 percent after 80 weeks in the TRIUMPH-1 study.
How much does retatrutide cost in the shop?
A 20 mg vial costs 200 EUR from Bio-Peptide and Genheal, and the 40 mg Nouveaux Ltd. Quick Pen costs 350 EUR.
Sources
- ClinicalTrials.gov, search for studies with the intervention retatrutide and LY3437943, accessed 17 October 2026. https://clinicaltrials.gov/search?intr=retatrutide
- Coskun T, Urva S, Roell WC et al. LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist for glycemic control and weight loss: From discovery to clinical proof of concept. Cell Metabolism, 2022, 34(9): 1234-1247. https://doi.org/10.1016/j.cmet.2022.07.013
- Urva S, Coskun T, Loh MT et al. LY3437943, a novel triple GIP, GLP-1, and glucagon receptor agonist in people with type 2 diabetes: a phase 1b, multicentre, double-blind, placebo-controlled, randomised, multiple-ascending dose trial. The Lancet, 2022, 400(10366): 1869-1881. https://doi.org/10.1016/S0140-6736(22)02033-5
- Jastreboff AM, Kaplan LM, Frías JP et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial. New England Journal of Medicine, 2023, 389(6): 514-526. https://doi.org/10.1056/NEJMoa2301972
- Jastreboff AM, Kaplan LM, Davies MJ et al. Retatrutide, a Triple Hormone Receptor Agonist, for Treatment of Obesity. New England Journal of Medicine, 2026. https://doi.org/10.1056/NEJMoa2604169
- Overgaard RV, Navarria A, Ingwersen SH et al. Clinical Pharmacokinetics of Oral Semaglutide: Analyses of Data from Clinical Pharmacology Trials. Clinical Pharmacokinetics, 2021, 60(10): 1335-1348. https://doi.org/10.1007/s40262-021-01025-x
- La Vignera S, Condorelli RA et al. Oral vs. Subcutaneous Semaglutide for Obesity Treatment: A Systematic Review of Efficacy, Safety, and Patient-Oriented Outcomes. Pharmaceuticals, 2026, 19(8). https://doi.org/10.3390/ph19081236
- Effect of Injection Site on the Relative Bioavailability of a Single Dose of LY3437943 in Healthy Participants With a High Body Mass Index, NCT05959096. https://clinicaltrials.gov/study/NCT05959096
- Pre-approval Expanded Access of Retatrutide (LY3437943), NCT07629401. https://clinicaltrials.gov/study/NCT07629401