Lyophilisation: difference between revisions
Diff·revision 37 → 38·02:24, 27 Mar 2025
Difference between revision 37 and revision 38 of Lyophilisation. 11 lines changed; the page grew by 2,221 bytes.
| Revision 37 — 03:11, 21 Mar 2025 CounterfeitCato (talk) merge two short sections 17,659 bytes ±0 | Revision 38 — 02:24, 27 Mar 2025 Chromatokid (talk) fix category — parent was wrong 19,880 bytes +2,221 | ||
|---|---|---|---|
| 112 | Residual moisture specifications for lyophilised peptides commonly sit below 3% w/w, and frequently below 1% for products intended for long ambient storage. Lower is not always better. For some proteins a monolayer of water appears to be required for conformational stability, and over-dried preparations have shown reduced stability relative to preparations dried to an intermediate moisture. The relationship between residual moisture and degradation rate is not monotonic and is formulation-specific.{{r|chang2009,wang2000}} | 112 | Residual moisture specifications for lyophilised peptides commonly sit below 3% w/w, and frequently below 1% for products intended for long ambient storage. Lower is not always better. For some proteins a monolayer of water appears to be required for conformational stability, and over-dried preparations have shown reduced stability relative to preparations dried to an intermediate moisture. The relationship between residual moisture and degradation rate is not monotonic and is formulation-specific.{{r|chang2009,wang2000}} |
| 113 | 113 | ||
| + | 114 | Stoppers contribute to the final moisture in a way that is easy to overlook. Elastomeric closures absorb water during steam sterilisation and release it slowly into the sealed headspace, so a vial can gain moisture during storage from its own closure. Post-sterilisation drying of stoppers, and the choice of a low-moisture-transmission elastomer, are the usual mitigations; the phenomenon is discussed further at [[vial]].{{r|iso8362_5}} | |
| + | 115 | ||
| + | 116 | == Formulation == | |
| + | 117 | A pure peptide dried from water alone often produces an unsatisfactory solid: a thin film at the vial base, a cake that shrinks away from the wall, or a residue that is difficult to see and easy to mistake for an empty vial. Formulation addresses cake structure, chemical stability and reconstitution behaviour simultaneously. | |
| + | 118 | ||
| + | 119 | ; Bulking agents : Mannitol and glycine crystallise on freezing and give an elegant, mechanically robust cake. Because they crystallise, they contribute little to the amorphous phase and therefore raise the permissible product temperature. Mannitol is the most widely used. | |
| + | 120 | ; Cryoprotectants and lyoprotectants : Sucrose and trehalose remain amorphous and protect by forming a glassy matrix in which the peptide is immobilised, and by hydrogen bonding to the solute in place of the water removed. The two mechanisms — vitrification and water replacement — are both supported by evidence and are not mutually exclusive.{{r|carpenter1997,chang2009}} | |
| + | 121 | ; Buffers : Buffer salts can crystallise selectively during freezing and shift pH substantially. Sodium phosphate is the classic example: crystallisation of the disodium salt during freeze concentration has been reported to drive pH down by several units, a change more than sufficient to accelerate hydrolytic degradation. Histidine and citrate buffers are less prone to this behaviour.{{r|carpenter1997}} | |
| + | 122 | ; Surfactants : Polysorbate 20 or 80 at low concentration reduces adsorption at the ice-water and air-water interfaces, a recognised route to aggregation during freezing.{{r|wang2000}} | |
| + | 123 | ||
| 114 | == References == | 124 | == References == |
| 115 | {{reflist}} | 125 | {{reflist}} |
| ⋮ | ⋮ | ||
| 125 | <ref name="murphy2005">Murphy DM, Koop T. "Review of the vapour pressures of ice and supercooled water for atmospheric applications." ''Quarterly Journal of the Royal Meteorological Society'' 131(608):1539–1565 (2005).</ref> | 135 | <ref name="murphy2005">Murphy DM, Koop T. "Review of the vapour pressures of ice and supercooled water for atmospheric applications." ''Quarterly Journal of the Royal Meteorological Society'' 131(608):1539–1565 (2005).</ref> |
| 126 | <ref name="usp1207">United States Pharmacopeia, General Chapter <1207>, "Package Integrity Evaluation — Sterile Products". USP–NF, current revision.</ref> | 136 | <ref name="usp1207">United States Pharmacopeia, General Chapter <1207>, "Package Integrity Evaluation — Sterile Products". USP–NF, current revision.</ref> |
| + | 137 | <ref name="iso8362_5">ISO 8362-5:2016, ''Injection containers and accessories — Part 5: Freeze drying closures for injection vials''. International Organization for Standardization.</ref> | |
| 127 | 138 | ||
| 128 | == See also == | 139 | == See also == |