The Body Pharm Retatrutide 64 Pen is a pre-filled research peptide device containing 64 mg of retatrutide total, diallable up to 8 mg per weekly injection following a 2 mg → 4 mg → 8 mg → 8–12 mg titration pattern.
Retatrutide is a GIP/GLP-1/glucagon triple-agonist that produced a mean 24.2% body-weight reduction at 48 weeks in the 2023 Phase 2 NEJM trial, with the Phase 3 TRIUMPH-1 topline (announced May 2026) subsequently reporting 28.3% at 12 mg over 80 weeks. The 64 mg pen is the highest-volume Body Pharm format, delivering roughly double the supply duration of the 32 mg pen — a more cost-efficient choice for protocols running 10 weeks or longer.
Research use only. Retatrutide is not authorised by the MHRA, FDA or EMA as of mid-2026 and remains an investigational compound. Supplied for in-vitro and laboratory research purposes only — not for human consumption.
Key Takeaways
- The 64 mg pen holds more peptide per pound than the 32 mg format, lowering the price-per-mg for longer protocols.
- Phase 2 data shows a mean 24.2% body-weight reduction at 12 mg weekly over 48 weeks; the Phase 3 TRIUMPH-1 topline reported 28.3% at 12 mg over 80 weeks (announced May 2026, peer-reviewed publication pending) [2][3].
- Retatrutide has no MHRA, FDA or EMA authorisation as of mid-2026 and remains investigational under the Phase 3 TRIUMPH programme (NCT05929066).
- The pen requires 2–8 °C refrigeration with no freeze-thaw cycles; JCSG.org ships with full cold-chain integrity to UK research addresses.
- A single 64 mg pen is one SKU and one lot number, removing mid-study re-order risk.
What is the Body Pharm Retatrutide 64 Pen?
The Body Pharm Retatrutide 64 Pen is a pre-filled research peptide injector containing 64 mg of retatrutide total. It carries the Body Pharm label and is sold through JCSG.org in the UK as a research chemical, not an authorised medicine [1]. That classification matters: retatrutide has no MHRA, FDA or EMA authorisation as of mid-2026, and the UK supply channel is positioned for in-vitro laboratory research use only because the compound remains investigational [1].
The device is a multi-dose pen with an on-pen dial running up to an 8 mg marker, so the operator can draw up to 8 mg per weekly administration in line with the 2 mg → 4 mg → 8 mg → 8–12 mg titration pattern [1].
Mechanistically, retatrutide is a triple agonist at the GIP, GLP-1 and glucagon receptors. That sets it apart from dual-agonist comparators because it activates three distinct metabolic pathways rather than two. Readers wanting the underlying pharmacology should consult the retatrutide overview page for receptor-binding and efficacy context, the 32 mg pen for the shorter-protocol format, or the tirzepatide page for a side-by-side with the dual GLP-1/GIP class.
Retatrutide's Triple-Agonist Mechanism Explained
Retatrutide (LY3437943) is a single-molecule triple agonist that hits the GLP-1, GIP and glucagon receptors simultaneously. Eli Lilly developed it, and the third receptor target distinguishes it from every other incretin-class peptide currently in clinical development [2]. That combined receptor profile is the pharmacological reason the 12 mg weekly dose produced a mean 24.2% body-weight reduction over 48 weeks in the Jastreboff et al. Phase 2 obesity trial published in the New England Journal of Medicine in 2023 — the largest single-agent reduction reported at that time [2].
How retatrutide differs from semaglutide and tirzepatide
Semaglutide is a mono-agonist. It binds the GLP-1 receptor only, driving satiety and slowed gastric emptying with no direct action at GIP or glucagon sites. Tirzepatide adds one receptor: it activates GLP-1 and GIP, layering on an insulinotropic and adipocyte-signalling effect absent from semaglutide. The receptor-binding contrast is laid out on the tirzepatide page. Retatrutide goes a step further by adding glucagon receptor co-agonism on top of GLP-1 and GIP activity.
Why the glucagon receptor matters
Glucagon receptor activation drives hepatic energy expenditure and lipolysis. That is the mechanistic basis researchers cite for retatrutide's weight-loss curves not plateauing at 48 weeks in the Phase 2 dataset — unlike the flattening typically seen with GLP-1 mono-agonists, because the liver continues to mobilise fat stores [2]. The trade-off: glucagon activity can transiently raise fasting glucose and heart rate, so the net glycaemic effect depends on GLP-1's insulinotropic dominance offsetting glucagon's hepatic output. The Body Pharm 64 pen titration ladder (2 mg → 4 mg → 8 mg → 8–12 mg) mirrors the Phase 2 escalation schedule used to manage that tolerability profile [1][2].
Current development status
Retatrutide remains investigational as of mid-2026. The Phase 3 TRIUMPH programme (NCT05929066) is ongoing; the TRIUMPH-1 topline announced in May 2026 reported a 28.3% mean reduction at 12 mg over 80 weeks, but the peer-reviewed publication is still pending, so the 2023 NEJM Phase 2 paper remains the primary published dataset [1][2][3]. Researchers wanting deeper receptor-binding context can consult the retatrutide overview before finalising a comparison protocol.
Clinical Evidence: What the Data Shows
The strongest published efficacy signal for retatrutide is a mean 24.2% body-weight reduction at 48 weeks in the 12 mg arm of the 2023 NEJM Phase 2 obesity trial by Jastreboff et al. [2]. The Phase 3 TRIUMPH-1 topline announced in May 2026 reported 28.3% at 12 mg over 80 weeks; that figure is a company topline, not yet a peer-reviewed publication, and should be treated as provisional until the full paper appears [3]. Researchers should note that trial pharmacology describes supervised participants, not the research-chemical sourcing context in which the Body Pharm pens are sold.
Trial design and dose arms
The Phase 2 trial randomised adults with obesity (BMI ≥30, or ≥27 with a weight-related complication) across placebo and four retatrutide dose ceilings: 1 mg, 4 mg, 8 mg and 12 mg, given subcutaneously once weekly with stepped titration. The primary endpoint was percentage change in body weight at 24 weeks, with a secondary endpoint at 48 weeks [2]. The 8 mg and 12 mg arms produced 22.8% and 24.2% reductions respectively. The curve had not flattened by week 48 because the triple-agonist profile continued to drive hepatic lipolysis [2]. That observation is what keeps interest alive in the triple-agonist profile relative to GLP-1 mono-agonists and the GLP-1/GIP dual agonism covered on the tirzepatide page.
Safety signals worth flagging
Jastreboff et al. reported dose-dependent gastrointestinal adverse events — nausea, diarrhoea, vomiting, constipation — as the dominant tolerability issue, alongside transient heart-rate increases that attenuated over time [2]. No unexpected safety signals surfaced at the doses tested. The trial was not powered or sized to detect rare events, and any research protocol design should account for that gap.
Phase 3 status and verification steps
The Phase 3 TRIUMPH programme (NCT05929066) is ongoing as of mid-2026. The TRIUMPH-1 topline (28.3% at 12 mg, 80 weeks) was announced in May 2026, but no peer-reviewed Phase 3 efficacy or safety publication has yet appeared to formalise it [1][2][3]. Retatrutide has not received FDA, EMA or MHRA authorisation by mid-2026 [1][2]. Before finalising a comparison protocol, verify the current TRIUMPH status directly on ClinicalTrials.gov and cross-check PubMed for any post-2023 peer-reviewed safety or pharmacokinetic publications. The retatrutide overview is the starting point for mechanism context, but registry data should drive any claim about current trial readouts.
32 mg vs 64 mg Pen: Which Format Should You Order?
The 64 mg pen delivers roughly double the supply duration of the 32 mg format at a lower price-per-mg — making it the more cost-efficient choice for protocols running beyond five weeks. The fixed overhead of ordering and cold-chain shipping spreads across twice the peptide content. The 32 mg pen suits shorter pilot work or first-time comparator runs. Both pens dial off the same on-pen 8 mg marker as the maximum single weekly dose [1]. Researchers concerned about lot-to-lot consistency should note that a single 64 mg SKU eliminates mid-study re-order risk.
Head-to-head specification table
| Specification | 32 mg pen | 64 mg pen |
|---|---|---|
| Total peptide content | 32 mg | 64 mg |
| Maximum single weekly dose (on-pen marker) | 8 mg | 8 mg |
| Doses at 8 mg weekly | 4 | 8 |
| Supply duration at 8 mg weekly | ~5 weeks (allowing titration) | ~10 weeks (allowing titration) |
| Titration pattern (label) | 2 → 4 → 8 mg | 2 → 4 → 8 → 8–12 mg |
| Price per mg | See buy box | See buy box |
| Mid-study re-order risk | Higher (shorter supply) | Eliminated (full protocol in one SKU) |
Which format fits which protocol
For a 10–12 week comparator study, or any protocol running the full titration arc (2 → 4 → 8 → 8–12 mg), the 64 mg pen is the clear buy. One SKU and one lot number eliminate mid-study re-order risk, and the lower price-per-mg compounds savings across the full protocol duration [1]. For a short tolerability pilot, a 4–5 week dose-finding window, or a first procurement where lot-to-lot consistency is still being assessed, the 32 mg pen is the lower-commitment entry point.
Either format sits in the same regulatory position: investigational, unauthorised by the MHRA, and mechanistically distinct from the dual GLP-1/GIP agonism profiled on the tirzepatide page. Pen format changes cost efficiency and protocol fit — not pharmacology.
Pen Operation and Storage for Research Use
The Body Pharm 64 mg pen ships pre-filled, so no reconstitution with bacteriostatic water is required before dosing [1]. That is the operational difference researchers should weigh against lyophilised vial formats: vials demand sterile reconstitution, accurate diluent measurement, and a stability clock that starts the moment water meets powder. The pen arrives ready to dial and inject. For longitudinal protocols running across 10–12 weeks, removing the weekly reconstitution step cuts handling variance between doses and reduces contamination risk from repeated vial punctures.
Dialling the dose
The 64 mg pen is dialled in whole-milligram increments using the on-pen marker, with supplier documentation referencing an 8 mg maximum single weekly dose to support the published 2 → 4 → 8 → 8–12 mg titration arc [1]. The exact total injection count at each titration step should be confirmed against the insert supplied with the pen.
Storage and stability
Standard peptide-handling practice for GLP-class agonists in aqueous pen format is refrigeration at 2–8 °C, no freezing, and protection from direct light and UV. Freeze-thaw cycles denature the peptide backbone; prolonged ambient excursions shorten the usable in-use window. Both are the most common avoidable causes of activity loss in injectable peptide formulations. Verify the carton insert before commencing a protocol. JCSG.org ships the Body Pharm 64 Pen with full cold-chain integrity to UK addresses.
For mechanistic background, the retatrutide overview covers the triple-agonist pharmacology in depth, and the tirzepatide page provides the dual GLP-1/GIP comparator most researchers benchmark against when designing handling protocols.
Ordering the Body Pharm Retatrutide 64 Pen in the UK
JCSG.org supplies the Body Pharm Retatrutide 64 Pen in the UK. The current GBP price is shown in the buy box at the top of this page.
Ordering details:
- GBP pricing shown in the buy box
- Cold-chain shipping at 2–8 °C from order to delivery
- Full Body Pharm product range, including the 32 mg pen for shorter protocols
- Batch number and expiry confirmed on every order
What to confirm before your order ships
- Carton insert with batch number and expiry is supplied
- Cold-chain shipping (2–8 °C) is confirmed end-to-end — JCSG.org maintains this by default
- The pen is the 64 mg total-content format, not a relabelled 32 mg unit
- The product is the current Body Pharm SKU, not older stock approaching expiry
For mechanistic context when evaluating the product, the retatrutide overview and the tirzepatide comparator page set the pharmacological baseline.
Regulatory Status
Retatrutide is not authorised by the MHRA as a medicine for human use as of mid-2026 [1]. It is supplied in the UK through the research peptide channel, not as a licensed therapeutic. Verify current MHRA status independently before any procurement decision.
Internationally, retatrutide (Eli Lilly development code LY3437943) has not received FDA or EMA marketing authorisation for any indication as of mid-2026 [1]. It remains investigational under the Phase 3 TRIUMPH programme (ClinicalTrials.gov NCT05929066); the TRIUMPH-1 topline announced in May 2026 has not yet been formalised in a peer-reviewed Phase 3 efficacy or safety dataset at time of writing [1][2][3].
Legislative framework and researcher obligations
The Human Medicines Regulations 2012 govern the manufacture, sale and supply of medicines in the UK, and assess a product's status by presentation, function and marketing claims rather than by a seller's disclaimer alone. Institutional researchers should route procurement through their governance or ethics committee and obtain independent legal review. This page is not legal advice.
Research use only. Supplied for laboratory research purposes only. Not for human consumption. Verify MHRA status before purchase.
Mechanistic background sits on the retatrutide overview page, with the tirzepatide comparator covering the licensed dual-agonist benchmark.
Related Peptides and Further Research Resources
Researchers comparing retatrutide against adjacent incretin and metabolic compounds can route through the site's broader peptide index for mechanistic context. The retatrutide overview page consolidates the triple-agonist pharmacology (GLP-1, GIP, glucagon) and links the 32 mg and 64 mg pen formats discussed here.
For comparator work, the tirzepatide page covers the dual GLP-1/GIP agonist benchmark and the semaglutide page the GLP-1 mono-agonist baseline. Adjacent metabolic peptide research areas worth scoping include MOTS-C and NAD⁺.
Browse all Body Pharm peptides.
Primary external references remain the Jastreboff et al. 2023 Phase 2 obesity trial in the New England Journal of Medicine and the ongoing TRIUMPH Phase 3 programme registered as NCT05929066 on ClinicalTrials.gov [2][3].
Sources
[1] Body Pharm Retatrutide 64 Pen product documentation (supplier label, JCSG.org listing). [2] 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. DOI: 10.1056/NEJMoa2301972 [3] Eli Lilly TRIUMPH-1 (Phase 3) retatrutide obesity trial — topline results announced May 2026; peer-reviewed publication pending. ClinicalTrials.gov NCT05929066.
