Do not shake. Swirl, or leave it. Vigorous agitation introduces air and shear, and neither helps a peptide go into solution any faster than patience does.
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Practice · Reconstitution · continued
A 10 mg vial reconstituted three different ways, compared — the long version posts 31–60
This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.
a.ibarra, post #30: Arithmetic step by step: a 5 mg vial with 2 mL of diluent gives (5 mg) / (2 mL) = 2.5 mg/mL. On a U-100 syringe at that concentration, 100 units = 1 mL = 2.5 mg, so each unit = 0.025 mg. A 0.25 mg dose = 0.25 / 0.025 = 10 units. Different concentration: different arithmetic, same principle. Happy to be the one who is wrong here if it… Go to post
Post #28 put the caveat in the right place and I want to underline it.
On 10 mg vial reconstituted three the community has more anecdote than the confidence in this thread implies, and I include my own contribution in that.
e.roos, post #6: The best check on any reconstitution calculation is to do it twice by two different routes — mass per volume, then volume per dose — and see whether they agree. They should, and when they do not it is nearly always the concentration step. Speaking for myself and not for anyone else who has posted here. Go to post
Preservative effectiveness is tested against a defined microbial challenge under defined conditions. It is not a licence to treat an entered vial as sterile indefinitely, and no supplier claims otherwise.
Nothing to add, except that this is the answer I would give if asked.
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Reconstituting the whole vial when you will use a quarter of it is a decision to store the rest in solution, which is the least stable state it will ever be in. Sometimes that is the right trade and it should be a decision.
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Do not shake. Swirl, or leave it. Vigorous agitation introduces air and shear, and neither helps a peptide go into solution any faster than patience does.
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b.teixeira, post #2: The confident answers on 10 mg vial reconstituted three and the well-sourced answers are not the same answers, which is the most useful thing I have learned reading this category. Go to post
Narrowing post #35, because the general version has more than one answer.
The thing about 10 mg vial reconstituted three 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.
Filter needles are worth considering if you are drawing from a glass ampoule and are pointless overhead for a stoppered vial. The trade is dead volume against particulate risk.
That is what the documentation says. What happens in practice is usually close.
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k.dahlberg, post #20: Do not shake. Swirl, or leave it. Vigorous agitation introduces air and shear, and neither helps a peptide go into solution any faster than patience does. Go to post
That is a cleaner way of putting what I was circling around.
KLindqvist, post #29: Two people can reconstitute the same vial to different concentrations and both be right. The dose is the same; only the volume drawn differs. This confuses more discussions here than any other single point. Adding the caveat now so it does not have to be extracted later. Go to post
Research-use-only material reconstituted at home is not a compounded sterile preparation and nothing about the procedure makes it one. Members describing what they do are not describing a pharmaceutical process.
I read post #37 twice before replying, because I had assumed the opposite.
The best check on any reconstitution calculation is to do it twice by two different routes — mass per volume, then volume per dose — and see whether they agree. They should, and when they do not it is nearly always the concentration step.
The right answer here may simply be that it has not been measured.
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Narrowing post #41, because the general version has more than one answer.
A vial that will not fully dissolve: check in order: is the diluent genuinely room temperature (some preservatives crystallise in cold), is the vial being warmed gently rather than shaken hard, is the injection technique clean, is the vial integrity intact. Work through that checklist before concluding the powder is insoluble.
Stating my assumptions rather than smuggling them in.
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s.grahame, post #5: Two things can be true about 10 mg vial reconstituted three at once: the mechanism is plausible and the evidence for the size of the effect is thin. Most of the argument here is people defending the first against attacks on the second. Go to post
For anyone finding this later: the short answer on 10 mg vial reconstituted three is that it depends on one thing, and the rest of the thread is people identifying which thing.
That is clearer than the version I had in my head. Thank you.
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Narrowing post #45, because the general version has more than one answer.
Do not shake. Swirl, or leave it. Vigorous agitation introduces air and shear, and neither helps a peptide go into solution any faster than patience does.
Anyone with a larger sample, please post it.
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l.ibarra, post #46: Narrowing post #45, because the general version has more than one answer. Do not shake. Swirl, or leave it. Vigorous agitation introduces air and shear, and neither helps a peptide go into solution any faster than patience does. Anyone with a larger sample, please post it. Go to post
Post #45 and I disagree about the size of the effect, not about the direction.
Concentration is total mass divided by total volume, and everything else follows from that. Ten milligrams into two millilitres is five milligrams per millilitre, and it does not matter how the vial was labelled before you added anything.
I have seen it go both ways, which is why I hedge.
p.novak, post #37: Narrowing post #35, because the general version has more than one answer. The thing about 10 mg vial reconstituted three 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. Go to post
Two people can reconstitute the same vial to different concentrations and both be right. The dose is the same; only the volume drawn differs. This confuses more discussions here than any other single point.
Adding the boring version of 10 mg vial reconstituted three, 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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Post #48 is right about the mechanism and I think understates the practical bit.
Do not shake. Swirl, or leave it. Vigorous agitation introduces air and shear, and neither helps a peptide go into solution any faster than patience does.
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h.oyelowo, post #17: 10 mg vial reconstituted three: I have looked for the primary source twice and failed twice. Either it does not exist or it is somewhere I do not know to look, and I would like to know which. Go to post
Coming back to post #50, because the follow-up matters more than the original answer.
Add the diluent down the side of the vial rather than directly onto the cake. It is slower and it avoids the foaming that makes people think something has gone wrong.
Reconstituting a multi-strength kit: if a kit contains 5 mg, 10 mg, 15 mg vials and you are reconstituting all of them, writing the concentration on each vial in permanent marker as you go is the single most useful thing you can do to avoid dose errors later.
I have written this out at length because the short version keeps being misread.
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10 mg vial reconstituted three: I would want to see the raw numbers rather than the summary before agreeing. Summaries lose exactly the information that would settle this.
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Marking my place. If it changes for me I will come back and say so.
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a.kirchner, post #43: For anyone finding this later: the short answer on 10 mg vial reconstituted three is that it depends on one thing, and the rest of the thread is people identifying which thing. Go to post
10 mg vial reconstituted three has a well-known answer and a correct answer, and the interesting work is establishing that they are the same. Nobody has done that here yet.
h.kimani, post #33: Preservative effectiveness is tested against a defined microbial challenge under defined conditions. It is not a licence to treat an entered vial as sterile indefinitely, and no supplier claims otherwise. Go to post
Filter needles are worth considering if you are drawing from a glass ampoule and are pointless overhead for a stoppered vial. The trade is dead volume against particulate risk.
I would rather post the uncertainty than round it away.
k.marchand, post #47: Post #45 and I disagree about the size of the effect, not about the direction. Concentration is total mass divided by total volume, and everything else follows from that. Ten milligrams into two millilitres is five milligrams per millilitre, and it does not matter how the vial was labelled before you added anything. I have seen it go… Go to post
Reconstituting the whole vial when you will use a quarter of it is a decision to store the rest in solution, which is the least stable state it will ever be in. Sometimes that is the right trade and it should be a decision.
If anyone can point at the primary source I would be grateful.