Retatrutide — analytical characterisation
Chromatographic conditions, identity, related substances, presentation, reconstitution and in-use stability.
§6Analytical characterisation
§6.1Chromatographic conditions
- Column
- C18, 2.1 × 150 mm, 1.7 µm, wide pore
- Mobile phase and gradient
- A: 0.1 % formic acid in water; B: 0.1 % formic acid in acetonitrile. Gradient 25–60 % B over 35 min, 50 °C
- Detection
- UV 214 nm
- Retention
- Comparable to tirzepatide; the two must be resolved deliberately because cross-contamination on a shared line is plausible
§6.2Identity by mass spectrometry
Expected deconvoluted average mass near 4731 Da. The Institute regards any supplier report giving a mass outside 4725–4740 Da without explanation as an identity failure rather than a purity finding.[3]
§6.3Related substances and degradation
Table 7. Related substances recorded for Retatrutide, with the process or storage route that generates each and its analytical signature.
| Related substance | Origin | Analytical signature |
|---|---|---|
| Sequence-variant material | Supplier synthesised a different published or unpublished analogue | Mass difference of tens to hundreds of daltons; the single most important finding to exclude |
| Tirzepatide cross-contamination | Shared synthesis or fill line | +82 Da difference in average mass; resolvable |
| Non-acylated backbone | Failed conjugation | Large negative mass shift; elutes early |
| Truncated chains | Incomplete coupling | Multiple species; produces a characteristic ladder in the chromatogram |
Degradation routes
- Not characterised in published stability-indicating studies
- Class-typical oxidation, aggregation and deamidation routes should be assumed
§7Presentation, reconstitution and storage
§7.1Presentation and reconstitution
- Presentation
- Investigational solution for injection (sponsor); lyophilised powder in vial (research-supply material)
- Reconstitution
- A 10 mg vial reconstituted with 2.0 mL gives 5 mg/mL; a 2 mg dose is then 0.40 mL, that is 40 units on a U-100 syringe.
- Storage, lyophilised
- 2–8 °C; −20 °C for extended storage of research material
- Storage, reconstituted
- 2–8 °C
- In-use period
- No stability-indicating in-use data are published. The Institute publishes no in-use claim.
Because supplier-to-supplier identity variation is the dominant risk for this compound, the Institute treats an independent mass-spectrometric identity confirmation as a prerequisite for any purity claim to be meaningful.
§7.2In-use stability
Applicable standards: CEI-MS-01 · CEI-MS-02 · CEI-MS-03 · CEI-MS-04 · CEI-MS-05 · CEI-MS-06. The full series is at methodological standards.
Working calculators: reconstitution and insulin-unit conversion · purity against peptide content · certificate minimum-data checker.
References cited on this page
References are numbered in order of first citation in this document. Each superscript in the text links to its entry below.
- United States Pharmacopeial Convention. General Chapter ⟨1225⟩ Validation of Compendial Procedures. United States Pharmacopeia — National Formulary (USP–NF) 2024;USP 2024 Issue 1. identifier not held by the Institute
- International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use. ICH Q2(R2) Validation of Analytical Procedures. ICH Harmonised Guideline 2023;Step 4 version, 1 November 2023. identifier not held by the Institute
- International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use. ICH Q6B Specifications: Test Procedures and Acceptance Criteria for Biotechnological/Biological Products. ICH Harmonised Tripartite Guideline 1999;Step 4 version. identifier not held by the Institute
- International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use. ICH Q1A(R2) Stability Testing of New Drug Substances and Products. ICH Harmonised Tripartite Guideline 2003;Step 4 version. identifier not held by the Institute
- Manning MC, Chou DK, Murphy BM, Payne RW, Katayama DS. Stability of protein pharmaceuticals: an update. Pharmaceutical Research 2010;27(4):544–575. doi:10.1007/s11095-009-0045-6 · PMID 20143256
Identifiers are reproduced only where the Institute holds them. Where a digital object identifier or PubMed identifier is not shown, the Institute has recorded the journal and year and has not constructed an identifier.