Vial: difference between revisions
Diff·revision 47 → 48·17:03, 22 Jun 2025
Difference between revision 47 and revision 48 of Vial. 7 lines changed; the page grew by 1,439 bytes.
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| 131 | The chapter also frames integrity in terms of a ''maximum allowable leakage limit'' — the largest leak that can be tolerated without compromising the product — which is to be established for the specific product rather than assumed. For microbial ingress, the leak size below which passage becomes improbable has been studied experimentally, and the frequently cited threshold of the order of a few micrometres derives from that work rather than from a compendial requirement.{{r|usp1207,kirsch1997}} | 131 | The chapter also frames integrity in terms of a ''maximum allowable leakage limit'' — the largest leak that can be tolerated without compromising the product — which is to be established for the specific product rather than assumed. For microbial ingress, the leak size below which passage becomes improbable has been studied experimentally, and the frequently cited threshold of the order of a few micrometres derives from that work rather than from a compendial requirement.{{r|usp1207,kirsch1997}} |
| 132 | 132 | ||
| + | 133 | For a lyophilised product, headspace analysis is a particularly informative method because it is non-destructive and answers two questions at once. Headspace pressure and oxygen concentration measured by laser absorption reveal both loss of integrity and gradual moisture or oxygen ingress, and the same measurement can be repeated on the same vial over time to give a rate rather than a single value.{{r|usp1207}} | |
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| + | 135 | == Delamination and glass defects == | |
| + | 136 | Inner-surface delamination is the detachment of thin glass flakes, conventionally called lamellae, from the interior wall of a vial. It came to prominence in 2010 and 2011 when several injectable products were recalled after lamellae were observed, and the Food and Drug Administration issued an advisory to manufacturers describing the phenomenon and its risk factors.{{r|fda2011}} | |
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| + | 138 | The mechanism is understood as a two-stage process. During forming, localised heating volatilises alkali and boron species from the glass surface, which redeposit as a layer of altered composition, chemically less durable than the bulk glass. In service, solution attacks that layer, and where attack is uneven the layer separates as flakes rather than dissolving. Risk factors identified in the advisory and in the literature include high pH, phosphate, citrate and tartrate buffers, terminal sterilisation, prolonged storage, and vials formed from tubing rather than moulded.{{r|fda2011,ennis2001}} | |
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| 133 | == References == | 140 | == References == |
| 134 | {{reflist}} | 141 | {{reflist}} |