This is the sort of exchange that makes the archive worth searching.
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Practice · Storage & stability · continued
Storing lyophilised material long term: what governs the shelf life posts 61–90
This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.
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I have been on both sides of the storing lyophilised material long term argument in this category within eighteen months, which should tell you how strong the evidence for either side is.
I had written a reply contradicting post #62 and deleted it. Here is what survived.
Clarity is a weak test. A solution can lose a significant fraction of its active content to degradation or adsorption while remaining perfectly clear.
That is the practical version. The rigorous version is longer and says the same thing.
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This follows post #64 rather than contradicting it.
The two questions that get merged here are whether material is degraded and whether it is contaminated. Storage affects both and they need different answers and different tests.
The confident version of this sentence would be wrong, so here is the hedged one.
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Worth separating two things that post #62 runs together.
Clarity is a weak test. A solution can lose a significant fraction of its active content to degradation or adsorption while remaining perfectly clear.
I would be glad to be shown a cleaner way of putting this.
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ka.haddad, post #38: The arithmetic in post #37 is right; the assumption feeding it is the part to check. For anyone finding this later: the short answer on storing lyophilised material long term is that it depends on one thing, and the rest of the thread is people identifying which thing. Go to post
The thing about storing lyophilised material long term that took me longest to accept is that a plausible mechanism is not evidence of an effect. It is a reason to look, not a result.
i.guerrero, post #53: Reconstituted material carried in a bag for a day is a temperature excursion even in a cool climate. Where that matters is cumulative exposure over weeks rather than a single afternoon. Worth saying I have only my own numbers here, and n is small. Go to post
Posting my storing lyophilised material long term numbers with the method attached so they can be discounted properly. Uncontrolled, unblinded, and collected by someone who wanted a particular answer.
Visible particulate is a strong signal in the other direction: it is a reason to stop and ask rather than to filter and proceed.
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Post #69 and I disagree about the size of the effect, not about the direction.
Protecting from light: amber vials or opaque containers reduce light exposure. If you are storing for long periods and light matters, this is worth doing. For short-term prepared solutions, ordinary storage away from direct sunlight is usually adequate.
It is worth checking rather than assuming, which costs nothing.
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m.vukovic, post #62: Container choice matters: the material of the vial, the rubber closure, the fill volume all affect how quickly the contents degrade. Smaller fill volumes lose less to adsorption. Glass vials lose less to leaching than plastics. Go to post
Taking post #69 at face value and following it one step further.
Visible particulate is a strong signal in the other direction: it is a reason to stop and ask rather than to filter and proceed.
This is the sort of thing that ought to be settled and apparently is not.
My position on storing lyophilised material long term is current rather than settled. I have revised it once already and I expect to again, so treat it accordingly.
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Worth stating the null on storing lyophilised material long term before we explain it: the observation may be nothing. That possibility deserves a sentence and usually does not get one.
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This follows post #73 rather than contradicting it.
If you are going to test stored material, test it against a sample of the same lot stored properly rather than against the certificate. Otherwise you are measuring the difference between two laboratories as well.
A partial answer, offered because a partial answer beats none.
l.vermeulen, post #41: Adding the measurement that post #38 says would settle it. Adding a reference point for storing lyophilised material long term. Mine is a single case, collected without controls, and I am posting the method alongside it so it can be discounted appropriately. Go to post
I read the earlier replies on storing lyophilised material long term twice before writing this, because I had assumed the opposite and wanted to be sure I was disagreeing with what was said rather than what I expected.
Fine by me. I had wanted a stronger conclusion and there is not one available.
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m.dumitru, post #24: Clarity is a weak test. A solution can lose a significant fraction of its active content to degradation or adsorption while remaining perfectly clear. Go to post
The most useful reply I ever got about storing lyophilised material long term was a request to state my units. It sounds like pedantry and it has saved me twice.
a.finnegan_rd, post #7: Building on post #6 rather than restating it. Visible particulate is a strong signal in the other direction: it is a reason to stop and ask rather than to filter and proceed. I have left out the parts I could not verify. Go to post
Visible particulate is a strong signal in the other direction: it is a reason to stop and ask rather than to filter and proceed.
Post #80 describes the usual case. This is about the unusual one.
Storing lyophilised material long term is one of those subjects where the general answer and the answer for a specific case diverge, and the thread will go in circles until someone says which one is being asked for.
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policy_reader, post #65: This follows post #64 rather than contradicting it. The two questions that get merged here are whether material is degraded and whether it is contaminated. Storage affects both and they need different answers and different tests. The confident version of this sentence would be wrong, so here is the hedged one. Go to post
Confirming post #82 from a second method, which matters more than confirming it from a second person.
Clarity is a weak test. A solution can lose a significant fraction of its active content to degradation or adsorption while remaining perfectly clear.
It is a small point and it changes the answer, which is an awkward combination.
z.szabo, post #1: On the subject in the title: Storing lyophilised material long term: what governs the shelf life Working notes rather than a conclusion. I have spent a fortnight trying to pin storing lyophilised material long term down and I want to set out where I have got to, because I suspect the honest answer is duller than the thread this will… Go to post
I keep a log for storing lyophilised material long term specifically because my memory of it turned out to be systematically wrong in one direction. Six weeks of notes cost nothing and settled it.
Picking up post #82: that is the part I would want checked first.
Adding the boring version of storing lyophilised material long term, because the interesting version keeps getting posted and the boring one is usually right.
Check the ordinary explanations, in order, and stop when one of them accounts for what you are seeing. Most of the time the second one does.
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On post #84 — agreed on the reasoning, with one qualification.
Dry storage in a freezer is generally more protective than a refrigerator for long periods, provided the material is genuinely dry and the container genuinely sealed. Condensation on removal is the trap.
That is a description of practice, not a recommendation of it.
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The confident answers on storing lyophilised material long term and the well-sourced answers are not the same answers, which is the most useful thing I have learned reading this category.
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Where I have landed on storing lyophilised material long term, having got it wrong once in public: the direction is clear, the magnitude is not, and anyone quoting a precise magnitude has borrowed it from somewhere that did not measure it.
d.ndiaye, post #22: On post #18 — agreed on the reasoning, with one qualification. Storing lyophilised material long term: I would want to see the raw numbers rather than the summary before agreeing. Summaries lose exactly the information that would settle this. Go to post
Noted, and thank you for writing it out rather than summarising it.