CEI-MS-20 — Photostability assessment of light-sensitive peptides
Photostability assessment of light-sensitive peptides
§1Scope
§1.1Scope
Applies to peptides containing tryptophan, tyrosine, methionine or cysteine, to copper complexes, and to any compound whose monograph records a photolytic degradation route. Several of the most widely supplied research peptides fall in this class, including two hexapeptides containing two tryptophan residues each.
§2Principle
Ultraviolet and visible radiation excites aromatic side chains, generating radical species that oxidise the excited residue and adjacent ones. Tryptophan is the most photolabile common residue, degrading through N-formylkynurenine and kynurenine intermediates with characteristic absorbance changes near 320 and 360 nm. The extent of degradation depends on total illumination, container transmittance and the presence of photosensitisers.[1,2]
§3Apparatus and reagents
§3.1Apparatus
- Photostability chamber with a combination of cool-white fluorescent and near-ultraviolet lamps, or a xenon source, meeting ICH option 1 or option 2
- Calibrated lux meter and ultraviolet radiometer
- Quinine chemical actinometer as an alternative to radiometry
- Amber and clear containers of the type used in supply
§3.2Reagents and reference materials
- Quinine hydrochloride for actinometry, where used
- Aluminium foil for dark controls
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.
- 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.