Tirzepatide — analytical characterisation
Chromatographic conditions, identity, related substances, presentation, reconstitution and in-use stability.
§6Analytical characterisation
§6.1Chromatographic conditions
- Column
- C18 or C8, 2.1 × 150 mm, 1.7–3.5 µm; wide-pore stationary phase preferred
- Mobile phase and gradient
- A: 0.1 % formic acid in water; B: 0.1 % formic acid in acetonitrile. Gradient 25–55 % B over 30 min at 0.3 mL/min, 50 °C
- Detection
- UV 214 nm; 280 nm confirmatory (Tyr1, Tyr10, Trp25)
- Retention
- Longer retention than semaglutide under matched conditions owing to the C20 diacid and greater hydrophobic surface
§6.2Identity by mass spectrometry
Positive-mode ESI gives [M+4H]⁴⁺ at m/z ≈ 1204.4 and [M+5H]⁵⁺ at m/z ≈ 963.7. Deconvoluted average mass should fall within 2.5 Da of 4813.5. The C-terminal amide is confirmed by a −0.98 Da difference from the free-acid form.[3]
§6.3Related substances and degradation
Table 7. Related substances recorded for Tirzepatide, with the process or storage route that generates each and its analytical signature.
| Related substance | Origin | Analytical signature |
|---|---|---|
| C-terminal free acid | Incomplete amidation or hydrolysis | +0.98 Da; near-coeluting, requires high-resolution MS |
| Des-Aib13 variant | Building-block omission | −85 Da |
| Non-acylated backbone | Failed side-chain conjugation | Approximately −750 Da; elutes markedly earlier and is diagnostic |
| Aspartimide at Asp9 | Base-mediated side reaction during synthesis | −18 Da; a recognised difficulty in this sequence |
| Semaglutide cross-contamination | Shared manufacturing line | Distinct mass and retention; the Institute regards its presence as a critical finding |
Degradation routes
- Tryptophan oxidation at Trp25 under light or peroxide stress (+16 Da)
- Aspartimide formation and subsequent isoaspartate
- Aggregation on agitation, accelerated above 30 °C
- Deamidation of the C-terminal amide in aqueous solution at elevated pH
§7Presentation, reconstitution and storage
§7.1Presentation and reconstitution
- Presentation
- Aqueous solution in single-dose pen or vial (approved products); lyophilised powder in vial (research-supply material)
- Reconstitution
- A 10 mg vial reconstituted with 1.0 mL gives 10 mg/mL. A 2.5 mg dose is then 0.25 mL, that is 25 units on a U-100 syringe. Reconstituting the same vial with 2.0 mL gives 5 mg/mL and moves the 2.5 mg dose to 50 units, improving measurement precision at the cost of injection volume.
- Storage, lyophilised
- 2–8 °C for labelled shelf life; −20 °C for long-term storage of research material
- Storage, reconstituted
- 2–8 °C, do not freeze
- In-use period
- Approved single-dose presentations are not intended for multi-dose in-use periods. The Institute publishes no in-use claim for reconstituted research material.
Tirzepatide is more hydrophobic than semaglutide and shows greater propensity to adsorb to untreated glass; reconstituted solutions should not be held at room temperature for extended periods.
§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.