Semax — analytical characterisation
Chromatographic conditions, identity, related substances, presentation, reconstitution and in-use stability.
§6Analytical characterisation
§6.1Chromatographic conditions
- Column
- C18, 4.6 × 250 mm, 5 µm
- Mobile phase and gradient
- A: 0.1 % trifluoroacetic acid in water; B: acetonitrile. Gradient 5–35 % B over 20 min
- Detection
- UV 214 nm; 258 nm (Phe4) and 211 nm (His3) — weak but usable aromatic confirmation
- Retention
- Early to intermediate
§6.2Identity by mass spectrometry
[M+H]⁺ at m/z 814.4. Average mass 813.9 ± 0.5 Da. Met1 oxidation adds 16 Da.[3]
§6.3Related substances and degradation
Table 7. Related substances recorded for Semax, with the process or storage route that generates each and its analytical signature.
| Related substance | Origin | Analytical signature |
|---|---|---|
| Met1 sulfoxide | Oxidation | +16 Da; an N-terminal methionine is highly oxidation-prone and this is the dominant impurity for the compound |
| Des-Met1 | Aminopeptidase cleavage or incomplete coupling | −131 Da |
| Histidine racemisation at position 3 | Coupling | Isobaric; histidine is racemisation-prone |
| Diketopiperazine at Pro-Gly-Pro | Cyclisation | −18 Da |
| Counter-ion | Purification | His and the N-terminus are the basic sites; content should be quantified |
Degradation routes
- N-terminal methionine oxidation dominates and proceeds readily in air
- Diketopiperazine formation in the proline-rich C-terminal region
- Histidine oxidation in the presence of trace metals
§7Presentation, reconstitution and storage
§7.1Presentation and reconstitution
- Presentation
- Intranasal solution (approved Russian presentations); lyophilised powder in research supply
- Reconstitution
- A 30 mg vial with 3.0 mL gives 10 mg/mL; a 300 µg quantity is then 0.03 mL, that is 3 units on a U-100 syringe, which is below the range a U-100 syringe measures reliably and argues for a more dilute preparation.
- Storage, lyophilised
- −20 °C, desiccated, protected from air
- Storage, reconstituted
- 2–8 °C. Because the N-terminal methionine oxidises readily, reconstituted solutions should be prepared in small volumes and used promptly
- In-use period
- No supported claim
An N-terminal methionine is the single most oxidation-labile common motif in peptide chemistry. For Semax the practical consequence is that headspace air in a partially used vial matters.
§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.