Drawing from a multi-dose vial — anyone have experience?

hank_denver said:

Practical: whatever you change, write down the date and the reason.

Thank you for spelling out the reasoning rather than just the conclusion. Sending this to two other people who asked me the same thing last week.

Adding the clinical framing, because it changes how the question reads. There is a difference between no evidence and evidence of no effect, and this subject is one where the two get swapped freely in both directions.

Moderator note: a couple of off-topic posts removed. No action needed from anybody.

TrialNerd_Beth said:

There is a difference between no evidence and evidence of no effect, and this subject is one where the two get swapped freely in both directions.

Adding the part of the answer the thread has not reached. The version of this that has an answer is narrower than the version being asked. Narrow it and it becomes tractable; leave it broad and the thread will produce nine confident and incompatible replies.

Adding the numbers, since they settle part of this. Say what you would expect to see if you were wrong, before you look. It is a small discipline and it changes what you notice.

That is the short version; the long version is somebody else's post.