Second pass at: A pen that felt like it delivered nothing: diagnosing it afterwards

Second pass at: A pen that felt like it delivered nothing: diagnosing it afterwards — setting out what I have, and where I think it stops being reliable.

Question about a metering device rather than about a syringe, because the failure modes are different.

The instruction leaflet is clear about priming and about the hold count at the end. It is silent about what I am asking, which suggests either that it does not arise or that it arises so rarely nobody wrote it down.

Which of those is it?

Reading rather than answering, but this is the post I would point somebody at.

Coming back to post #3, because the follow-up matters more than the original answer.

Comparing cost per milligram between a pen and a vial ignores wastage, dead volume and the number of doses actually obtainable. Cost per delivered dose at your dose is the comparison that survives.

Holding the pen in place for the stated count after the plunger stops is the manufacturer's answer to leakage at the site. It is on the instruction leaflet and it is the step most often skipped.

The claim is narrower than it sounds, and deliberately so.

Disposal of a used pen is a sharps question even where the needle is retracted, and local rules vary more than people expect.

A partial answer, offered because a partial answer beats none.