Lyophilisation: difference between revisions
Diff·revision 50 → 51·08:06, 20 Jul 2025
Difference between revision 50 and revision 51 of Lyophilisation. 5 lines changed; the page grew by 1,312 bytes.
| Revision 50 — 13:36, 9 Jul 2025 SupplyWatchSuri (talk) add short description 23,467 bytes ±0 | Revision 51 — 08:06, 20 Jul 2025 DMF_Dermot (talk) add {{refimprove}}24,779 bytes +1,312 | ||
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| 144 | Reconstitution time and clarity detect collapse, over-concentration and incipient aggregation. A cake that requires prolonged agitation, or that yields a hazy solution, is a documented indicator of physical instability even when chemical assay is within specification.{{r|wang2000}} | 144 | Reconstitution time and clarity detect collapse, over-concentration and incipient aggregation. A cake that requires prolonged agitation, or that yields a hazy solution, is a documented indicator of physical instability even when chemical assay is within specification.{{r|wang2000}} |
| 145 | 145 | ||
| + | 146 | == Why lyophilised material tolerates ambient shipping == | |
| + | 147 | The practical significance of lyophilisation for distribution is that it removes the dominant degradation pathway. Hydrolytic reactions require water and molecular mobility; a dry amorphous glass held below its glass transition temperature provides neither in quantity. Reported consequences are large. Degradation rates for peptides in the dry state are commonly two to three orders of magnitude below rates for the same peptide in solution at the same temperature, and the temperature sensitivity of the residual degradation is correspondingly lower.{{r|chang2009,wang2000}} | |
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| + | 149 | This is the basis for the common practice of shipping lyophilised research peptides at ambient temperature without refrigeration, and for manufacturers' statements that a lyophilised product tolerates transient warming. It is not a licence to disregard temperature entirely. The glass transition temperature of a dry peptide-sucrose matrix may be only 40–70 °C; a parcel left in a vehicle in summer can plausibly approach that range, and above it the matrix devitrifies and mobility rises sharply. Moisture ingress through a compromised seal has the same effect, because water plasticises the glass and lowers its transition temperature by tens of degrees.{{r|chang2009}} | |
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| 146 | == References == | 151 | == References == |
| 147 | {{reflist}} | 152 | {{reflist}} |