Retatrutide vs Semaglutide: the triple agonist against the original

The newest molecule in the incretin class against the one that started it. Trial data, mechanism, side effects and Philippine registration status for both.

Philippines Peptides editorial deskUpdated 3 November 20269 min read

Video guide: Retatrutide vs Tirzepatide vs Semaglutide (2:18)

Part of: Retatrutide in the Philippines

Reta TRIUMPH-1, 80 wk: 28.3%
Sema STEP 1, 68 wk: 14.9%
Reta receptors: 3
Sema receptors: 1

Quick comparison

These two sit at opposite ends of the incretin class. Semaglutide activates one receptor, GLP-1. Retatrutide activates three: GLP-1, GIP and glucagon. In the Philippines they also sit in completely different regulatory positions.

Factor	Retatrutide	Semaglutide
Mechanism	GLP-1 + GIP + Glucagon	GLP-1 only
Receptors	3	1
Mean body-weight change, highest arm	28.3% at 80 wk (TRIUMPH-1, phase 3, 12 mg arm)	14.9% at 68 wk (STEP 1, phase 3, 2.4 mg arm)
US FDA status	Investigational	Approved (Ozempic, Wegovy, Rybelsus)
FDA Philippines	No registered drug product found on the FDA verification portal	Registered only as branded prescription medicines: Ozempic, Wegovy and Rybelsus (17 certificates of product registration)
PH pharmacy route	None	Branded medicines, with a prescription
Post-approval data	None, trial data only	Years, at scale

Our partner and supplier

Research vials: cost per mg

Product	Price	Per mg
Primara Labs Retatrutide 20mg research vial20 mg per vial	₱3,390₱2,076 each in a 10-pack	₱170₱104 in a 10-pack
Primara Labs Tirzepatide 15mg research vial15 mg per vial	₱1,890₱1,155 each in a 10-pack	₱126₱77 in a 10-pack
Primara Labs Semaglutide 15mg research vial15 mg per vial	₱1,990₱1,216 each in a 10-pack	₱133₱81 in a 10-pack

Research vials are not approved for human use, are sold for research only, and must be reconstituted.

Stocked in Metro Manila; same-day delivery there for orders before 12 noon
Lab report: Janoshik, batch RETA-4728-A, retatrutide, bacterial endotoxin only; not identity or purity. Key H2KI86I8GWB4, batch reports
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See retatrutide at Primara See tirzepatide at Primara See semaglutide at Primara Ask on WhatsApp

Primara Labs is our partner and supplier.

Short answer

How they actually work

Semaglutide is pure GLP-1 receptor agonism: satiety signalling to the brain, slower gastric emptying, improved insulin response. It is the most-studied version of the incretin mechanism.

Retatrutide keeps that GLP-1 base, adds GIP, and then adds the glucagon receptor. Glucagon receptor activation acts on hepatic fat oxidation and energy expenditure, and it is the main mechanistic difference between the two molecules. It is also why retatrutide appears in liver-fat research, covered in the retatrutide liver research filing.

Efficacy head-to-head

In TRIUMPH-1, an 80-week phase 3 trial of 2,339 adults with obesity, or overweight with at least one weight-related condition, without diabetes, body weight fell by 19%, 25.9% and 28.3% on the 4 mg, 9 mg and 12 mg arms, against 2.2% on placebo. In STEP 1, a 68-week phase 3 trial of 1,961 adults with BMI of 30 or greater (27 or greater with at least one weight-related coexisting condition), without diabetes, body weight fell by 14.9% on the 2.4 mg arm, against 2.4% on placebo. No trial has run the two head-to-head, so the comparison is two strong data points rather than one controlled answer.

The earlier phase 2 retatrutide trial is history rather than the headline: In Retatrutide phase 2 (Jastreboff), a 48-week phase 2 trial of 338 adults with a BMI of 30 or more, or 27 to under 30 with at least one weight-related condition, body weight fell by 8.7%, 17.1%, 22.8% and 24.2% on the 1 mg, 4 mg (pooled), 8 mg (pooled) and 12 mg arms, against 2.1% on placebo.

Tirzepatide, the two-receptor middle step, gives context. In SURMOUNT-1, a 72-week phase 3 trial of 2,539 adults with BMI of 30 or more, or 27 or more with at least one weight-related complication, excluding diabetes, body weight fell by 15%, 19.5% and 20.9% on the 5 mg, 10 mg and 15 mg arms, against 3.1% on placebo. In SURMOUNT-5, a 72-week phase 3b trial of 751 adults with obesity but without type 2 diabetes, body weight fell by 20.2% on the Tirzepatide, maximum tolerated dose arm, against 13.7% on semaglutide, maximum tolerated dose. A head-to-head phase 3 trial of retatrutide against tirzepatide, TRIUMPH-5, has not read out.

Side effect profile

Both compounds produce the class-standard gastrointestinal effects, nausea first among them. The trial figures, with the comparator arm alongside:

Retatrutide, TRIUMPH-1 (an 80-week phase 3 trial of 2,339 adults with obesity, or overweight with at least one weight-related condition, without diabetes):

Discontinuation for adverse events: 4.1%, 6.9% and 11.3% on the 4, 9 and 12 mg arms, against 4.9% on placebo.
Nausea: 28.6%, 38.4% and 42.4% on the 4, 9 and 12 mg arms, against 14.8% on placebo.
Diarrhoea: 25.2%, 34.1% and 32% on the 4, 9 and 12 mg arms, against 13.5% on placebo.
Constipation: 23.8%, 25.9% and 26.1% on the 4, 9 and 12 mg arms, against 10.9% on placebo.
Vomiting: 10.6%, 22.8% and 25.3% on the 4, 9 and 12 mg arms, against 4.8% on placebo.
Dysesthesia: 5.1%, 12.3% and 12.5% on the 4, 9 and 12 mg arms, against 0.9% on placebo.
Urinary tract infection: 7.5%, 8.8% and 8.4% on the 4, 9 and 12 mg arms, against 5.3% on placebo.

Semaglutide, STEP 5 (a 104-week phase 3 trial of 304 adults with obesity, or overweight with at least one weight-related comorbidity, without diabetes). The synced dataset carries no adverse event rows for STEP 1:

Discontinuation for adverse events: 5.9% on the 2.4 mg arm, against 4.6% on placebo.
Gastrointestinal adverse events: 82.2% on the 2.4 mg arm, against 53.9% on placebo.
Nausea: 53.3% on the 2.4 mg arm, against 21.7% on placebo.
Diarrhoea: 34.9% on the 2.4 mg arm, against 23.7% on placebo.
Constipation: 30.9% on the 2.4 mg arm, against 11.2% on placebo.
Vomiting: 30.3% on the 2.4 mg arm, against 4.6% on placebo.

Availability in the Philippines

Retatrutide: No registered drug product found on the FDA verification portal. It has no pharmacy route; availability, legal status and the batch report are in the retatrutide Philippines guide. It exists in the Philippines only as research-grade material sold for laboratory research, which is not a registered medicine and not a substitute for a prescribed pen. Under RA 9711 a drug must be registered with FDA Philippines before it is imported, sold or distributed; the regulation hub sets out what that means.

Frequently asked questions

Is retatrutide better than semaglutide?

On the published trials, retatrutide produced the larger body-weight reduction. In TRIUMPH-1, an 80-week phase 3 trial of 2,339 adults with obesity, or overweight with at least one weight-related condition, without diabetes, body weight fell by 19%, 25.9% and 28.3% on the 4 mg, 9 mg and 12 mg arms, against 2.2% on placebo. In STEP 1, a 68-week phase 3 trial of 1,961 adults with BMI of 30 or greater (27 or greater with at least one weight-related coexisting condition), without diabetes, body weight fell by 14.9% on the 2.4 mg arm, against 2.4% on placebo. These are separate trials in different populations and of different lengths, not a head-to-head comparison. Semaglutide is a registered prescription medicine in the Philippines with years of post-approval safety data; retatrutide is investigational and has no registered product in any market.

How much more weight loss did retatrutide produce than semaglutide in trials?

The 12 mg arm of TRIUMPH-1, an 80-week phase 3 trial of 2,339 adults with obesity, or overweight with at least one weight-related condition, without diabetes, lost 28.3% of body weight on average. The 2.4 mg arm of STEP 1, a 68-week phase 3 trial of 1,961 adults with BMI of 30 or greater (27 or greater with at least one weight-related coexisting condition), without diabetes, lost 14.9%. No trial has compared the two directly, so the gap between those figures is an indication rather than a controlled answer.

Where are retatrutide and semaglutide sold in the Philippines?

Semaglutide: Registered only as branded prescription medicines: Ozempic, Wegovy and Rybelsus (17 certificates of product registration). Those medicines are dispensed by pharmacies against a prescription, and prescribing belongs with a licensed Philippine physician. Retatrutide: No registered drug product found on the FDA verification portal; it has no pharmacy route and exists in the Philippines only as research-grade material sold for laboratory research, which is not a registered medicine and not a substitute for a prescribed pen.

Is retatrutide available in Philippine pharmacies?

No. Retatrutide is investigational and has no registered product in any market. For the Philippines: No registered drug product found on the FDA verification portal. Semaglutide is the pharmacy-available molecule of the two, as branded prescription medicines.