Retatrutide vs TirzepatideThe Comparison You''ve Seen Is Wrong

Nearly every source — blogs, X, Reddit, so-called "experts" — tells you retatrutide has three receptors it hits vs. two for tirzepatide, and retatrutide beats tirzepatide for weight loss (24% to 21%). Both of those claims are meaningless, and the rest of the reasoning that follows from them — which drug to choose, when to switch, whether to microdose — inherits the error.

The "three receptors vs two" framing implies additive pharmacology: one more lever, one more effect. The real difference is not the extra receptor. Retatrutide's GIP engagement is nearly nine times more potent than tirzepatide's at the same receptor — same target, dramatically different signaling per molecule. Its GLP-1 engagement is about twice as potent. The third receptor, glucagon, engages progressively with dose — producing real hepatic effects at 1 mg and progressively more peripheral effects (heart-rate elevation, cold extremities, sustained lipolysis) as dose climbs through the 4–12 mg range. One receptor dialed up tenfold, another softened less, a third that operates on a dose-differentiated split between hepatic work (present at every dose) and systemic work (emerges with titration).

The 24% vs 21% figure fails a different way. The 24% comes from a 338-person Phase 2 trial of retatrutide at 12 mg, measured at 48 weeks. The 21% comes from a ~2,500-person Phase 3 trial of tirzepatide at 15 mg, measured at 72 weeks. Different duration, different phase, different analytic method, different sample size by nearly an order of magnitude. The three-point gap between them is partly real and partly artifact of the comparison itself. Swap in TRIUMPH-4's 28.7% reading — a different retatrutide trial, in adults with knee osteoarthritis, at 68 weeks — and the gap grows. The number isn't a result. It's a slice someone chose to quote.

The entire downstream decision — switching, microdosing, starting from scratch, stepping back because of side effects — lives on the other side of those two claims. Pick the drug on the misreading and you're choosing between "stronger" and "weaker." Pick it on the real comparison and you're choosing between two different pharmacologies with different dose-response shapes, different side-effect profiles, different ceilings, and different answers to the question of what "low dose" even means. The rest of this is about what that actually looks like.

At a Glance

For a decision framework scoped to your goal, jump to the four-camps table. For the separate liver fat story, jump to Liver Fat Is a Different Decision. For the pharmacology behind the equivalences, continue below.

These Are Not Two Versions of the Same Drug

Tirzepatide is a dual agonist: one molecule engaging GIP and GLP-1 receptors at specific engineered potencies. Retatrutide is a triple agonist: one molecule engaging GIP, GLP-1, and glucagon receptors — with every one of those engagements tuned to a different strength than tirzepatide's.

Three asymmetries fall out of this table that matter for every downstream decision.

GIP amplification. Retatrutide's GIP engagement is nearly nine times stronger than tirzepatide's at the same receptor. One molecule of retatrutide produces the same GIP signaling as roughly nine molecules of tirzepatide bound to identical receptors. It's the largest single pharmacological difference between the two drugs, and it's what makes retatrutide's low-dose behavior qualitatively different from tirzepatide's. A 1 mg retatrutide dose produces more GIP signaling than 15 mg of tirzepatide does¹.

GLP-1 softening with a wider margin. Both drugs pull back on GLP-1 relative to native signaling — tirzepatide to 20%, retatrutide to 40%. GLP-1 at full potency is what makes pure GLP-1 agonists like semaglutide produce severe nausea and food aversion. Retatrutide's GLP-1 arm is twice as potent as tirzepatide's, which shows up in side-effect rates at matched weight-loss outcomes later in this piece.

Glucagon as a dose-differentiated third receptor. Tirzepatide has no glucagon arm. Retatrutide's glucagon is a partial agonist at 30% native potency — and the way it manifests clinically depends on dose in a way that doesn't match the pattern of the other two receptors.

At low dose (1–2 mg), the glucagon arm is doing real work at the liver. Hepatic receptors sit at high local drug concentration because subcutaneous-injected retatrutide reaches the liver through the portal circulation at concentrations higher than peripheral plasma measurements capture. At 1 mg, the drug is already driving meaningful hepatic fatty-acid oxidation and producing measurable liver fat reduction. The systemic glucagon effects — heart-rate elevation, cold extremities, sustained lipolysis — are subtle at this dose and emerge slowly, over months of chronic use.

At mid-to-high dose (4–12 mg), the peripheral glucagon signaling comes fully online. Heart-rate elevation appears within weeks, dysesthesia emerges at the top of the range, resting metabolic rate lifts more meaningfully. The same mechanism producing subtle long-term effects at 1 mg produces pronounced faster-onset effects at 8–12 mg.

What this means for the comparison: retatrutide at microdose is GIP-amplified with quiet but active hepatic glucagon. Retatrutide at max dose is GIP-saturated with full systemic glucagon engagement. Tirzepatide has neither end of that spectrum.

One molecule, three different pharmacologies across its dose range. This is why retatrutide does not behave like "more tirzepatide" — and why a blanket comparison at top dose misses the real decision surface.

The Four Camps: What Dose Matches What Goal

The weight-loss equivalences across the two drugs collapse into four camps. Each camp answers a specific goal, and each is anchored in Phase 2 or Phase 3 trial data (see annex for the triangulation).

Two plain readings fall out of the table.

Retatrutide uses meaningfully less drug than tirzepatide at matched weight-loss outcomes. Retatrutide's 2 mg produces roughly what tirzepatide's 4–5 mg does. Retatrutide's 5 mg produces what tirzepatide's 10 mg does. The ratio compresses as dose climbs — at 8 mg reta vs 15 mg tirz, the outputs are similar — but through most of the therapeutic range, retatrutide delivers the same outcome from a smaller dose.

Tirzepatide has a real ceiling around 20%. Retatrutide has headroom. In SURMOUNT-1, the gain from tirzepatide 10 mg to 15 mg was 1.4 percentage points of additional weight loss² — most tirzepatide patients above 10 mg are buying a slight bump with added side effects. Retatrutide's 8 → 12 mg step adds roughly 2 points but brings the full glucagon-class side-effect spectrum online. Both drugs have diminishing returns at the top; retatrutide's diminishing returns are just higher up the curve.

These equivalences hold for weight loss. They don't hold for side effects — and they break entirely for liver fat.

Liver Fat Is a Different Decision

If the goal is weight loss, the four camps above are the decision surface. If the goal is liver fat — MASLD, NAFLD, elevated hepatic fat on imaging, or cardiometabolic risk tied to visceral and hepatic compartments — the decision is different. Different dose, different ceiling, different timeline, different drug.

Retatrutide does a lot more to the liver than tirzepatide does. Sanyal 2024 measured liver fat reduction directly via MRI-PDFF in 98 adults with obesity and ≥10% baseline liver fat — the same Phase 2 dose arms as the main obesity trial, non-diabetic population⁶.

Three things in this table reshape the retatrutide decision.

Liver fat is a 24-week story, not a 48-week one. At 8 mg, the 24-week liver fat reduction (81.4%) is indistinguishable from the 48-week reduction (81.7%) — 99.6% of the effect is already captured at the halfway point. Weight loss continues through 48 weeks; liver fat doesn't. The active hepatic mechanism runs its course in the first six months, then hits the physiological floor (~2.1% absolute liver fat, the UK Biobank median). This isn't a long-haul outcome.

8 mg is the effective ceiling for liver fat. At 24 weeks, retatrutide 8 mg produces 81.4% reduction; 12 mg produces 82.4%. A one-percentage-point gain at 12 mg in exchange for the full glucagon-class side-effect spectrum — dysesthesia at 20%, peak HR elevation, severe GI — is not the trade that makes sense for a liver-fat-primary goal. For someone optimizing hepatic outcomes, the ceiling lives at 8 mg.

1 mg retatrutide is a complete microdose treatment for hepatic steatosis. The 1 mg arm produces 43% liver fat reduction at 24 weeks — matching semaglutide 2.4 mg's 72-week result and exceeding tirzepatide 15 mg's 52-week result in SYNERGY-NASH⁷. At one-eighth the dose of retatrutide's top arm, in one-third the time. 27% of 1 mg participants reached normal liver fat (<5%) at 24 weeks; 57% at 4 mg; 79% at 8 mg; 86% at 12 mg.

The mechanism separating retatrutide from the rest of the class: glucagon signals the liver to actively oxidize stored triglycerides, independent of caloric deficit. Semaglutide and tirzepatide reduce liver fat passively — less caloric intake means less substrate arriving at the liver for storage. Retatrutide reduces liver fat actively — the liver is signaled to burn its existing fat stores. The β-hydroxybutyrate biomarker, which tracks hepatic fatty-acid oxidation directly, rose +93% at 4 mg and +181% at 12 mg in the Sanyal substudy — the signature of active glucagon-driven lipid mobilization⁶.

Curious about decomposition: at each retatrutide dose, how much of the liver fat reduction is passive (weight-loss-driven, the same mechanism semaglutide uses) versus active (the glucagon-specific contribution)? Using semaglutide's liver-fat-per-weight-loss ratio as the no-glucagon baseline, the decomposition at 24 weeks:

The active glucagon contribution to liver fat reduction is roughly constant — ~20 percentage points — across every retatrutide dose from 1 mg to 12 mg. The hepatic mechanism saturates early. Higher doses don't deliver more hepatic work; they deliver more peripheral work, which shows up as side effects. At 1 mg, half the liver fat reduction is coming from active glucagon-driven oxidation. At 12 mg, most of the reduction is the passive weight-loss component catching up to where glucagon already was at 1 mg.

This changes the use case for retatrutide substantially. Someone with MASLD or elevated hepatic fat, low-moderate BMI, interested in hepatic intervention without heavy weight-loss machinery: 1 mg retatrutide for 24 weeks is a complete treatment. Not a partial dose on the way to something stronger. The full hepatic effect lives at microdose.

For the South Asian metabolic pattern, family history of type 2 diabetes, or other phenotypes where visceral and hepatic fat accumulate at lower BMIs than cardiovascular risk scoring assumes, this is the compound whose mechanism most directly addresses the compartment driving the risk. The question shifts from "how much weight loss do I need" to "how much liver fat do I need to mobilize" — and the dose that answers the second question is lower than the one that answers the first.

Resting energy expenditure tracks the same active glucagon mechanism at attenuated magnitude. Class-comparator data (mazdutide, survodutide) supports a 3–7% REE elevation at retatrutide's top dose, proportionally less at lower doses. No direct REE measurement on retatrutide exists in published trials yet, but the weight-loss trajectory at 8–12 mg — continuing to descend through 48 weeks without the adaptive plateau that pure caloric restriction produces — is consistent with the glucagon arm holding metabolic rate above the normal weight-loss-adapted baseline. The "burn more" effect is real; the magnitude at microdose is small but not zero.

Side Effects Diverge Even at Matched Weight Loss

Same number on the scale, different felt experience. At each equivalence point in the four-camps table, the pharmacology producing the outcome is structurally different, and the side-effect profile follows.

Retatrutide 2 mg vs Tirzepatide 5 mg (~10–13% weight loss)

Retatrutide 2 mg engages the GLP-1 receptor at roughly five times the level tirzepatide 5 mg does³ — translating to more nausea, more gastric slowing, more food aversion. Tirzepatide 5 mg sits near the upper bound of what the body naturally produces on the GLP-1 axis after a meal. Retatrutide 2 mg sits four times above that threshold.

The glucagon arm at 2 mg is quiet peripherally but doing real hepatic work. No meaningful heart-rate elevation; cold extremities rare at this dose; dysesthesia not seen. BMR lift small but present. Liver fat reduction substantial (~50% projected at 24 weeks).

For someone who tolerates GI side effects poorly, tirzepatide at 5 mg is the cleaner way to reach 10–13%. For someone who wants the hepatic mechanism alongside the weight loss, or who cannot tolerate the dose volumes of tirzepatide, retatrutide at 2 mg delivers both at lower total drug burden — at the cost of more nausea during titration.

Retatrutide 5 mg vs Tirzepatide 10 mg (~20% weight loss)

Same weight loss, qualitatively different side effects. Retatrutide 5 mg activates the peripheral glucagon arm meaningfully — resting heart rate rises 5–7 bpm in the first 12–24 weeks, attenuating toward dulaglutide-comparable levels by week 36⁴. Cold extremities can emerge subtly. Tirzepatide 10 mg has no glucagon engagement at any dose; its side-effect burden is concentrated in GI and is well-characterized over multi-year exposure.

Liver fat outcome diverges sharply: retatrutide 5 mg reaches roughly 70% reduction at 24 weeks; tirzepatide 10 mg reaches perhaps 35–40% over the longer trial duration, mostly passive.

Retatrutide 8–12 mg vs Tirzepatide 15 mg (ceiling territory)

Tirzepatide 15 mg produces 21% weight loss at 72 weeks with nausea rates near 40%. The curve has flattened. Retatrutide 8 mg already matches tirzepatide's ceiling, with the glucagon arm fully online and the hepatic mechanism saturated. Retatrutide 12 mg reaches ~27% with severe nausea (50%+), peak heart-rate elevation, and dysesthesia (tingling, numbness, burning sensations, usually in extremities) occurring in about 20% of patients at top dose versus <1% on placebo⁵.

A person choosing retatrutide 12 mg over tirzepatide 15 mg is buying 5–6 percentage points of weight loss with a qualitatively expanded side-effect envelope. That's a different trade than "more drug, more side effects." It's a different category of drug.

The glucagon-class side effects are not arbitrary — they're the same mechanism that produces the desirable hepatic work at low dose, scaled to peripheral tissues at high dose. Heart rate, cold fingers, sustained lipolysis, and liver fat mobilization all emerge from glucagon receptor engagement. At 1 mg the signal reaches the liver; at 8–12 mg it reaches everything else. The ceiling of the beneficial mechanism and the onset of the problematic one track the same underlying variable.

The Microdose Case

Camp 1 — the lean, metabolically-minded person interested in GIP-driven benefit, hepatic work, and subtle metabolic-rate support without aggressive appetite suppression — is where retatrutide occupies a pharmacologic space tirzepatide cannot reach with current dosing.

The direct trial data: retatrutide at 1 mg weekly produced 8.7% weight loss and 43% liver fat reduction in Phase 2 adults with obesity, non-diabetic⁶ ⁸. Tirzepatide at 1 mg was tested only in Phase 2 type 2 diabetes — no non-diabetic 1 mg arm has ever been run — and produced 0.9 kg weight loss over 26 weeks, which is negligible. Projected to matched conditions (72 weeks, non-diabetic), the low-dose comparison:

The per-milligram advantage at microdose is an order of magnitude larger than at therapeutic dose. The mechanism is the GIP amplification. At 1 mg retatrutide, GIP receptor engagement produces signaling roughly eight times stronger than tirzepatide generates at its 15 mg top label dose¹. The GLP-1 arm is active but moderate — above the level the body produces after a meal, below the level that generates severe nausea. The glucagon arm is saturated at the liver (driving real hepatic fat mobilization) and quiet peripherally (no cardiac, minimal cold, modest BMR lift). What 1 mg retatrutide delivers is a coordinated three-receptor engagement at levels that produce meaningful metabolic work without bringing the full dose-limiting spectrum online.

Retatrutide 0.5 mg is a different case. Rosenstock 2023 tested 0.5 mg flat in T2D (n=46); the arm did not separate from placebo on either weight loss or HbA1c over 36 weeks⁹. Projected to non-diabetic populations: 1.5–3% weight loss and ~15% liver fat reduction at 48 weeks. Real pharmacology — GIP engagement is meaningful, hepatic glucagon at low signaling still doing some work — but the weight-loss outcome is marginal. The use case for 0.5 mg is metabolic optimization without appetite suppression: someone not trying to lose weight, interested in low-level incretin signaling for metabolic maintenance. For weight-loss intent, 1 mg is the defensible floor.

For tirzepatide, there is no equivalent microdose band. Tirzepatide 1 mg in non-diabetic populations has not been trialed; the extrapolation from T2D Phase 2 projects to ~2% weight loss over 72 weeks — near the noise floor. Tirzepatide's 2.5 mg label starter is officially a titration-only dose, not a therapeutic one.

If the goal is metabolic benefit at the lowest possible drug burden, retatrutide 0.5–1 mg is the only dose in the GLP-1 family with a defensible signal. And if the goal is hepatic intervention specifically, 1 mg retatrutide delivers 43% liver fat reduction at 24 weeks — a complete NAFLD treatment at a dose that barely registers in conventional weight-loss pharmacology.

Switching From Tirzepatide to Retatrutide

Where the Ceilings Actually Sit

Retatrutide and tirzepatide both have ceilings. They sit in different places for different endpoints.

Tirzepatide's weight-loss ceiling is known and conclusive. The dose-response flattens above 10 mg. 15 mg adds 1.4 points over 10 mg. No trial has tested higher. Compounded vials sold at 30 mg or 60 mg are containers for sub-15 mg dosing; chronic-exposure safety data ends at 15 mg weekly, and the dose-response curve gives no efficacy reason to exceed it.

Retatrutide's weight-loss ceiling at 12 mg (~27% projected 72 weeks) is the top of the Phase 2 range, not a saturation point. Phase 2 stopped at 12 mg because that was the protocol. The 8 → 12 mg step adds ~2 percentage points with substantial side-effect cost. Whether doses above 12 mg produce additional weight loss is unknown and, given the side-effect spectrum already at 12 mg, unlikely to be tested.

Retatrutide's liver-fat ceiling sits lower, at 8 mg. The active hepatic mechanism saturates there; 12 mg produces a 1-percentage-point gain at 24 weeks for a full glucagon-class side-effect spectrum. Anyone optimizing for hepatic outcomes specifically has no reason to exceed 8 mg.

TRIUMPH-5 (NCT06662383) is the Phase 3 trial that will compare retatrutide and tirzepatide head-to-head at matched populations and doses. Readout is late 2026 at earliest. Until then, every claim about "retatrutide is X% better than tirzepatide" is an indirect comparison across non-matched trials. The comparison available now is good enough to decide between the two drugs for most reader scenarios. The final polish arrives in 2027.

FAQ

Related Reading

For deep dives on each compound independently:

• Tirzepatide Guide: Dosing, Results & Side Effects — the full tirzepatide dose-response, SURMOUNT-1 body composition, and the mechanism behind the tirzepatide vs semaglutide split.
• Retatrutide: A Coherent Multi-Receptor Signal — the extended retatrutide pharmacology, receptor occupancy math, and hepatic-fat evidence.
• Tirzepatide Microdosing — where tirzepatide's microdose story actually rests.
• Retatrutide + NAD+ Protocol — the beginner stack applicable to any GLP-1 starter.
• GLP-1 Lean Mass Preservation — the body-composition story across semaglutide, tirzepatide, and retatrutide.

For dose calculators: tirzepatide dosage calculator and retatrutide dosage calculator. For side-by-side compound exploration: GLP-1 comparison tool.

Annex: The Math

The dose-equivalence framework rests on three primary-source reconstructions, each cross-validated against direct trial data.

Free-drug plasma concentrations

Tirzepatide's free-drug fraction is 0.29% (Willard 2020, reproducing Lilly's published pRO table exactly)¹⁰. Retatrutide's free-drug fraction is assumed 0.29% by structural analogy (same C20 fatty-diacid albumin anchor); not publicly disclosed. At linear dose-proportional PK, free-drug Cav,ss scales with dose:

Receptor occupancy

Applying EC50 values from Willard 2020 (tirzepatide: GIPR 1.01 nM, GLP-1R 6.54 nM) and Coskun 2022 / Li 2024 (retatrutide: GIPR 0.0643 nM, GLP-1R 0.775 nM, GCGR 5.79 nM)¹¹ ¹², and the standard occupancy formula pRO = [free Cav,ss] / ([free Cav,ss] + EC50):

Tirzepatide:

Retatrutide:

Effective signaling is pRO × intrinsic efficacy relative to native. At 1 mg retatrutide, GIPR signaling is 54% × 8.9× native = ~330% of native GIP max. At 15 mg tirzepatide, GIPR signaling is 41% × 1× native = 41% of native. The 1 mg retatrutide GIP signaling is ~8× tirzepatide's 15 mg.

Nausea threshold

Willard's reference frame: endogenous meal-stimulated GLP-1 produces GLP-1R pRO of 1–4%. Above this threshold, chronic signaling exceeds what the body naturally produces post-meal and nausea becomes clinically evident.

Observed nausea rates scale with GLP-1R pRO above the 1–4% endogenous band.

Weight-loss projection (72 wk non-diabetic)

Tirzepatide anchored in SURMOUNT-1 direct data (5/10/15 mg × 72 wk); extrapolated downward via the NCT03131687 Phase 2 T2D data and the population-responsiveness multiplier.

Retatrutide anchored in Jastreboff 2023 Phase 2 direct data (1/4/8/12 mg × 48 wk); projected to 72 wk using the observed 24 → 48 week trajectory at each dose; sub-1 mg extrapolated from Rosenstock 2023 T2D 0.5 mg data and the population multiplier.

Liver fat reduction (Sanyal 2024, 24 wk non-diabetic MASLD)

Direct Phase 2 data, baseline liver fat 19.1% by MRI-PDFF:

Active vs passive decomposition (using semaglutide's weight-loss-driven liver fat ratio as the no-glucagon baseline):

The active glucagon contribution to liver fat reduction is roughly constant at ~17–23 pp across every retatrutide dose from 1 mg to 12 mg. Hepatic saturation occurs at 1 mg; higher doses add weight-loss-driven passive reduction, not additional active mobilization.

Side-effect temporal dynamics

Retatrutide heart-rate elevation: peaks ~7 bpm at 12 mg in weeks 12–24, attenuates to non-significant vs dulaglutide 1.5 mg by 36 weeks (Rosenstock 2023)⁹. Tirzepatide has no meaningful heart-rate signal at any dose. Retatrutide dysesthesia: 20.9% at 12 mg vs 0.7% placebo at 48 weeks (Jastreboff 2023)⁵. Tirzepatide has no dysesthesia signal. GI side effects: dose-dependent in both drugs, retatrutide 13% at 0.5 mg → 50% at 12 mg (Rosenstock), tirzepatide 5–40% across the 5 → 15 mg range (SURMOUNT-1).

References

¹ Retatrutide GIP signaling vs tirzepatide — occupancy × intrinsic efficacy derivation, Annex. Source EC50 and potency data: Coskun T et al. (2022) Cell Metab 34:1234–1247 [DOI 10.1016/j.cmet.2022.07.013]; Li Y et al. (2024) Cell Discov 10:77; Willard FS et al. (2020) JCI Insight 5:e140532.

² Tirzepatide 10 → 15 mg dose-response flattening — SURMOUNT-1 Phase 3 results, 72 weeks, BMI ≥ 27 non-diabetic. Jastreboff AM et al. (2022) N Engl J Med 387:205–216 [DOI 10.1056/NEJMoa2206038].

³ Retatrutide 2 mg vs tirzepatide 5 mg GLP-1R engagement — 16.4% pRO vs 3% pRO — Annex receptor occupancy tables.

⁴ Retatrutide heart-rate temporal dynamics — peaks ~7 bpm early, attenuates to dulaglutide-comparable by 36 weeks. Rosenstock J et al. (2023) Lancet 402:529–544 [DOI 10.1016/S0140-6736(23)01053-X].

⁵ Retatrutide dysesthesia at top dose — 20.9% at 12 mg vs 0.7% placebo, 48 weeks. Jastreboff AM et al. (2023) N Engl J Med 389:514–526 [DOI 10.1056/NEJMoa2301972].

⁶ Retatrutide MASLD substudy — 98 adults with obesity + ≥10% baseline liver fat, non-diabetic, 48 weeks. 1 mg produced 43% liver fat reduction at 24 weeks; 12 mg produced 82%. β-hydroxybutyrate elevation +181% at 12 mg confirms active hepatic fatty-acid oxidation. Sanyal AJ et al. (2024) Nat Med 30:2037–2048 [DOI 10.1038/s41591-024-03018-2]; PMCID PMC11271400.

⁷ Cross-drug liver fat comparisons — semaglutide ~50% at 72 weeks; tirzepatide ~47% at 52 weeks in SYNERGY-NASH (T2D); dulaglutide ~32% at 24 weeks. Comparator values as reported in Sanyal 2024 discussion (p. 2044).

⁸ Retatrutide 1 mg weight loss — Phase 2 obesity trial, 48 weeks, n=69, non-diabetic, treatment-regimen estimand. Jastreboff AM et al. (2023) N Engl J Med 389:514–526, NCT04881760.

⁹ Retatrutide 0.5 mg in T2D — no separation from placebo on weight or HbA1c, 36 weeks, n=46. HR dynamics: peaks early, attenuates to dulaglutide-comparable by 36 weeks. Rosenstock J et al. (2023) Lancet 402:529–544, NCT04867785.

¹⁰ Tirzepatide free-drug fraction (0.29%) and receptor occupancy math — Willard FS et al. (2020) JCI Insight 5:e140532, Table 1.

¹¹ Retatrutide receptor EC50 values — cAMP functional agonism assay. Coskun T et al. (2022) Cell Metab 34:1234–1247.

¹² Retatrutide structural characterization, C20 fatty-diacid albumin anchor — Li Y et al. (2024) Cell Discov 10:77.

Additional references: Schneck K et al. (2024) CPT Pharmacometrics Syst Pharmacol — tirzepatide population PK (n=5,802); FDA Mounjaro label §12.3 (2022) and Zepbound label §12.3 (2023) — 99% albumin binding, 80% bioavailability, 5-day half-life; PMC12544991 — network meta-analysis comparing tirzepatide and retatrutide across 12 trials.

TRIUMPH-5 head-to-head trial (NCT06662383) — matched populations and doses, Phase 3, readout anticipated late 2026. TRIUMPH-Outcomes (NCT06383390) — n=10,000 cardiovascular/renal outcomes trial, readout later.