Retatrutide / Cagrilintide

The combination has never been studied, so it is graded D. On their own, retatrutide and cagrilintide are each graded B.

Strengths: 12.5 mg / 2.5 mg
Also known as: Reta / Cagri blend, LY3437943 + AM833
Contains: Retatrutide 12.5 mg, Cagrilintide 2.5 mg
Molecule: Two lipidated peptides in a fixed 5:1 mix
CAS: 2381089-83-2 (retatrutide); 1415456-99-3 (cagrilintide)

Origin

A pre-mixed vial of two experimental drugs from different companies: retatrutide (Eli Lilly) and cagrilintide (Novo Nordisk). No company is developing this pairing.

How it works

Retatrutide acts on GLP-1, GIP and glucagon receptors; cagrilintide activates amylin and calcitonin receptors that signal fullness through the brainstem. The rationale is borrowed from other amylin-plus-incretin pairings that showed added effects, but whether this holds alongside retatrutide's glucagon activity is untested.

What the research shows

A PubMed search found no study of retatrutide combined with cagrilintide or any amylin drug, only reviews. The concept rests on different combinations: cagrilintide plus semaglutide (CagriSema) and Lilly's eloralintide plus tirzepatide, both of which reported more weight reduction than either drug alone, along with more gastrointestinal events. Combined tolerability, stability of the two peptides together, and heart-rate effects are all unknown.

Key studies

REDEFINE 1, NEJM 2025 Context only (different pairing): cagrilintide + semaglutide −20.4% vs −3.0% placebo, counting everyone randomized.
Lilly EloraTZP phase 2b, 2026 Context only: eloralintide + tirzepatide −23.3% vs −14.8% for tirzepatide alone.

Safety findings

No data for the combination. Expected concerns are the sum of both components: gastrointestinal effects, dehydration risk, retatrutide's skin-sensation changes and heart-rate rise, and incretin-class pancreatitis, gallbladder and thyroid concerns.

Regulatory status

Neither component is FDA-approved (retatrutide is in phase 3; cagrilintide is under FDA review only as part of CagriSema), and there is no lawful compounding pathway for either. Retatrutide is not on WADA's 2026 list; cagrilintide's status is not confirmed.

Catalog notes

Offered as 12.5/2.5 mg; current lot RTCAG15-0803 has a certificate (99.70% purity, COA7594). Check the lot's certificate for the exact cagrilintide formula and molecular weight; reference sources list C194H312N54O59S2, 4409.07 g/mol and 37 residues. Follow the storage stated on the label and certificate.