Ipamorelin — analytical characterisation
Chromatographic conditions, identity, related substances, presentation, reconstitution and in-use stability.
§6Analytical characterisation
§6.1Chromatographic conditions
- Column
- C18, 4.6 × 150 mm, 3.5 µm; a chiral or polysaccharide-based phase is required to confirm D-amino-acid configuration
- Mobile phase and gradient
- A: 0.1 % trifluoroacetic acid in water; B: acetonitrile. Gradient 15–45 % B over 20 min
- Detection
- UV 214 nm; 280 nm strong (naphthyl and phenyl chromophores make this an unusually favourable peptide for 280 nm detection)
- Retention
- A pentapeptide with substantial aromatic and naphthyl content retains longer than its mass would suggest
§6.2Identity by mass spectrometry
[M+H]⁺ at m/z 712.4 and [M+2H]²⁺ at m/z 356.7. A 712 Da pentapeptide is small enough that a nominal-mass instrument gives a usable identity check, unlike the larger analogues in this series.[3]
§6.3Related substances and degradation
Table 7. Related substances recorded for Ipamorelin, with the process or storage route that generates each and its analytical signature.
| Related substance | Origin | Analytical signature |
|---|---|---|
| L-enantiomer at position 3 or 4 | Incorrect building block | Isobaric — undetectable by mass spectrometry and invisible on a standard reverse-phase method. Requires a chiral method or amino-acid analysis after hydrolysis. The Institute has not seen this test reported on any research-supply certificate |
| C-terminal free acid | Incomplete amidation | +0.98 Da; a 0.14 % relative mass change on a 712 Da peptide, at the limit of low-resolution detection |
| Des-Aib1 | Incomplete coupling | −85 Da |
| 2-Nal to 1-Nal regioisomer | Wrong naphthylalanine isomer | Isobaric; chromatographically resolvable with a shallow gradient |
| Acetate or trifluoroacetate | Counter-ion | Proportionally very large for a small peptide — a 712 Da peptide with one TFA per basic site carries approximately 14 % counter-ion by mass, so peptide content well below 90 % is expected and is not a defect |
Degradation routes
- Hydrolysis of the C-terminal amide
- No methionine or cysteine, so oxidation and disulfide routes do not apply
- Diketopiperazine formation at the N-terminus under thermal stress
- Racemisation at the D-centres under strongly basic conditions
§7Presentation, reconstitution and storage
§7.1Presentation and reconstitution
- Presentation
- Lyophilised powder in vial (research supply only)
- Reconstitution
- A 5 mg vial with 2.0 mL gives 2.5 mg/mL; a 200 µg quantity is 0.08 mL, that is 8 units on a U-100 syringe.
- Storage, lyophilised
- −20 °C, desiccated
- Storage, reconstituted
- 2–8 °C. No stability-indicating data are published for reconstituted ipamorelin and the Institute publishes no in-use claim
- In-use period
- No supported claim
For small peptides the arithmetic of counter-ion content matters disproportionately. A certificate reporting 98 % purity and 85 % peptide content for ipamorelin is internally consistent and describes acceptable material; a certificate reporting 98 % purity with no content figure has not told the reader how much peptide is in the vial.
§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.