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Retatrutide Pre-filled Pen 20mg Weight Loss

Le plus grand volume, prêt à l'emploi.

The largest volume of our pen range, for anyone who has already found their rhythm. A triple GLP-1, GIP and glucagon agonist, delivered ready to use: nothing to reconstitute, nothing extra to buy, the dose set on a dial. Volume for volume, it is the pen that costs least per milligram, and the one that spares you the most orders across a year. Four needles are included: you inject the day it arrives, no pharmacy run. For research use.

5mg99,00 €10mg139,00 €20mg199,00 €

199,00 €

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39 in stock, ready to ship

Next dispatch: Saturday, October 3

In stock in France

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Your complete kit

20mg penIn the box
4 needlesIn the box
Nothing else to buyReady to use

The solution is ready and the needles are included: set the dose on the dial and you are good to go. Keep the pen in the fridge (2 to 8 °C).

The largest volume in our pen range. Retatrutide is a triple agonist of the GLP-1, GIP and glucagon receptors; this ready-to-use format removes reconstitution and dose calculation, and offers the lowest cost per milligram among our pens. It suits those who have already settled into a routine.

Science

01
Mechanism of action

Retatrutide acts simultaneously on three receptors: GLP-1, GIP and glucagon. This triple action distinguishes it from GLP-1-only agonists such as semaglutide, and from dual GLP-1/GIP agonists such as tirzepatide. Published work covers glycaemic regulation, gastric emptying and energy expenditure. This is a research compound: available data come from ongoing clinical studies and do not constitute a therapeutic indication.

Clinical data

02Clinical studies

Clinical data on retatrutide are still recent but spectacular. The pivotal phase II obesity trial Jastreboff 2023 NEJM (Retatrutide Phase 2 Obesity Trial) tested 1/4/8/12mg weekly in 338 obese non-diabetic adults over 48 weeks. Mean weight loss: -8.7% (1mg), -17.1% (4mg), -22.8% (8mg), -24.2% (12mg) vs -2.1% placebo. At 12mg, 92% of participants lost >= 5%, 75% >= 15%, 56% >= 20%, and 26% lost >= 25%. These figures are the highest ever published for an anti-obesity pharmacological agent and directly rival sleeve gastrectomy bariatric surgery (typically -25% at 1 year).

Phase II diabetes study Rosenstock 2023 Lancet: 281 T2D patients over 36 weeks with doses 0.5/4/8/12mg. HbA1c: -2.02% at 12mg vs -0.01% placebo; weight loss -16.94% vs -3.0% placebo at 12mg. Retatrutide demonstrated an effect equivalent or superior to the best GLP-1 mono-agonists on diabetes while producing markedly stronger weight loss.

Phase II hepatic steatosis study Sanyal 2024 Lancet: retatrutide 5-10mg weekly in 98 patients with MASLD and obesity, over 48 weeks. Hepatic fat fraction reduction: -57.0% (5mg), -81.4% (10mg) vs -0.3% placebo. At 10mg, 85% of patients reached hepatic fat fraction < 5% (resolution threshold), 74% had >= 30% reduction. These results exceed those of any other pharmacological agent tested on MASLD, including tirzepatide in SYNERGY-NASH.

Phase III TRIUMPH trials are ongoing. TRIUMPH-1 (adult obesity, n=2250), TRIUMPH-2 (obesity with comorbidities), TRIUMPH-3 (type 2 diabetes + obesity), TRIUMPH-4 (MASH with fibrosis), TRIUMPH-6 (sleep/OSA): results expected 2025-2027. The program was designed to demonstrate broad superiority vs tirzepatide (direct comparator in certain arms) on weight loss, metabolic improvement, hepatic steatosis, and sleep apnea.

Tolerance profile: in phase II trials, gastrointestinal adverse events (nausea, vomiting, diarrhea, constipation) are frequent but mostly mild-to-moderate and concentrated in the early titration weeks. Adverse-event discontinuation rate was 6-16% depending on dose. Two signals deserve vigilance: mean heart rate increase of 3-7 bpm (similar to tirzepatide, likely linked to the GLP-1 arm), and modest ALT elevation in some patients (likely linked to GCGR-induced hepatic lipolysis). Retatrutide did not produce significant hypoglycemia in non-diabetics, confirming that the glucagon arm is properly balanced by the incretin arm.

In research these references structure protocols. The standard phase II titration was: 2mg W1-4, 4mg W5-8, 8mg W9-12, 12mg W13+ (progression by 4mg steps every 4 weeks). Researchers seeking to reproduce Jastreboff 2023 conditions use this schema as reference. Phase III trials test extended plateaus up to 16mg in certain arms, reflecting the possibility of an unsaturated dose-response even at 12mg.

1
ObésitéTriple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial
Jastreboff AM, Kaplan LM, Frías JP, et al. · New England Journal of Medicine · 2023
2
Diabète type 2Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a phase 2 trial
Rosenstock J, Frías J, Jastreboff AM, et al. · The Lancet · 2023

The listed studies are provided for documentation and research purposes only. They do not constitute a therapeutic indication nor a recommendation for human use. This product is strictly for laboratory use only (RUO).

Lab workflow

03
Research protocols

A pre-filled pen requires no reconstitution. The solution is ready to use: no powder to dissolve, no bacteriostatic water to add, no volume to calculate. That is the essential difference from a vial.

Before first use. Take the pen out of the fridge ten to fifteen minutes beforehand: a cold solution is more uncomfortable to inject, and this is the most common cause of discomfort. Check that the liquid is clear and colourless. A cloudy appearance or visible particles means it should not be used.

Attaching the needle. Remove the cap, screw on one of the needles supplied with the pen, then remove both needle covers. Use a new needle for every injection, never reuse one.

Priming. Before the very first injection from a new pen, set the dial to the smallest graduation and press the button until a droplet appears at the tip. This clears air from the cartridge and ensures the following dose is complete. It is not repeated for subsequent injections.

Setting the dose and injecting. Turn the dial to the desired figure. Pinch the skin lightly, insert the needle at ninety degrees, press the button fully and hold for ten seconds before withdrawing: this ensures the full dose has been delivered. Withdrawing too early is the most common mistake.

Afterwards. Remove the needle, dispose of it in a sharps container, replace the cap and return the pen to the fridge. Rotate the injection site each time.

WarningTheoretical tool for chemical handling. Does not constitute medical advice.

What is normal on arrivalThe observations that worry customers, and are not defects

The pen carries a handwritten marking: the product initials and the dose. This is our dose marker on the pen body. Check that it matches your order.
The needles are in the box, not on the pen. Four screw-on needles, a new one for each injection.
The liquid is clear and colourless, sometimes with a small air bubble. That is expected. Priming, before the first injection, clears the bubble.
The parcel is plain. Nothing on the outside indicates the contents or the brand name.

What is not normal: cloudy or coloured liquid, visible particles, a cracked pen or a dial that will not turn. In those exact cases, write to us with a photo and we will take the pen back.

Handling

04Storage & handling

Store the pen between +2 °C and +8 °C, refrigerated and away from light. This is an important difference from lyophilised powder, which tolerates room temperature: a pen contains an already-reconstituted solution and therefore requires continuous refrigeration.

Never freeze it. A solution that has been frozen and thawed should be discarded, even if it looks normal.

Take the pen out a few minutes before injecting: this noticeably reduces discomfort without breaking the cold chain.

It tolerates a few hours out of the fridge during transport, between the delivery point and home. Return it to the cold as soon as you receive it.

01Do I need to add bacteriostatic water?

No, and that is the whole point of this format. The solution is already prepared inside the cartridge. Bacteriostatic water is only needed for vials of lyophilised powder.

02Are needles included with the pen?

Yes, they are included. You receive the pen ready to use with its needles: nothing else to buy, no bacteriostatic water, no syringes, no trip to the pharmacy. Use a new needle for each injection and dispose of it in a sharps container.

03How many doses does a pen contain?

That depends entirely on the dose you set. A pen holds a fixed total quantity: the smaller the individual dose, the more injections it provides. Simply divide the pen total by your dose.

04What if the pen has been left out of the fridge?

A few hours at room temperature, such as during transport, is not a problem: return it to the cold as soon as possible. Prolonged or repeated exposure, however, compromises the solution. If in doubt after several days out of refrigeration, discard the pen.

05Why hold for ten seconds after pressing?

Because liquid continues to flow after the button reaches the bottom. Withdrawing the needle immediately leaves part of the dose in the pen or on the skin. This is the most common mistake with this format, and it goes unnoticed.

06Is the content the same as in your vials?

Yes, molecule for molecule. The difference lies in the packaging: the solution is prepared and dosed in advance, the concentration is fixed, and the product requires refrigeration. Vials remain cheaper per milligram.

07Can a pen be shared between several people?

No, under no circumstances, even when changing the needle. A pen is strictly individual: the mechanism can retain traces of biological material after injection.

Comparatif

Pen or vial?

Pen or vial? The contents are identical molecule for molecule. What changes is everything around it.

With a vial, you buy the powder, then bacteriostatic water, then insulin syringes. You reconstitute it yourself, work out your concentration, and convert your dose into syringe units. The vial costs less per milligram and lets you choose the concentration.

With a pen, there is nothing else to buy, needles are included, nothing to prepare and nothing to calculate: the dose is read off a dial. In exchange, the concentration is fixed and the pen must be kept refrigerated.

The vial suits those already comfortable with the process who want to optimise cost. The pen suits those coming from a pen-based treatment, those starting out, or anyone who would rather not handle a syringe.

Full guide: Retatrutide — mechanism, studies, dose comparison

Metabolism

Product information

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