Lyophilisation: difference between revisions
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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 | Headspace composition is set at stoppering. Vials sealed under partial vacuum or under nitrogen exclude oxygen and thereby suppress [[Methionine oxidation|methionine oxidation]] during storage; vials sealed at atmospheric pressure in air do not. Headspace pressure is measurable non-destructively by laser-based headspace analysis, which is also used as a container-closure integrity method under USP <1207>.{{r|usp1207}} | |
| + | 147 | ||
| 146 | == Why lyophilised material tolerates ambient shipping == | 148 | == 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}} | 149 | 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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| 168 | * Franks F. "Freeze-drying of bioproducts: putting principles into practice." ''European Journal of Pharmaceutics and Biopharmaceutics'' 45(3):221–229 (1998). | 170 | * Franks F. "Freeze-drying of bioproducts: putting principles into practice." ''European Journal of Pharmaceutics and Biopharmaceutics'' 45(3):221–229 (1998). |
| 169 | * Pikal MJ. "Freeze-drying of proteins: process, formulation, and stability." ''ACS Symposium Series'' 567:120–133 (1994). | 171 | * Pikal MJ. "Freeze-drying of proteins: process, formulation, and stability." ''ACS Symposium Series'' 567:120–133 (1994). |
| + | 172 | ||
| + | 173 | == External links == | |
| + | 174 | * [https://www.iso.org/ ISO 8362 series (catalogue entry)] — Standards for injection containers, closures and freeze-drying closures. Paywalled; abstracts are public. | |
| 170 | 175 | ||
| 171 | == See also == | 176 | == See also == |