Revisiting: Completing a dose with a second syringe, and the dead-volume arithmetic

Revisiting: Completing a dose with a second syringe, and the dead-volume arithmetic Writing it up because I had to work it out twice and would rather nobody else did.

I have read the maintained page on this and I still have a gap, so I am asking rather than guessing.

Context: tirzepatide, 23 weeks in, currently at a dose I reached by the standard four-week steps. Everything below is my own record rather than anything a clinician told me.

The specific question is the one in the title. What I have already checked: the labelling summary on the relevant documentation page, the two most-linked topics in this subcategory, and my own notes from the last 6 weeks. What I could not find is whether the answer changes at higher doses or whether it is the same arithmetic throughout.

If the answer is "it depends", I would rather know what it depends on than be given a number.

Air in the syringe is a much smaller problem subcutaneously than the anxiety about it suggests, and it is still worth expelling because the bubble occupies volume you meant to be liquid.

On the opening post — agreed on the reasoning, with one qualification.

If you have to inject at a different time of day than usual, that is a much smaller perturbation than it feels for a weekly compound with a week-long half-life.

I have said this before in a thread nobody could find, so it is worth repeating.

Picking up the opening post: that is the part I would want checked first.

Reframing Completing a dose slightly, because I think the disagreement is about the question rather than the answer. If the question is "does it happen", yes. If it is "how often", nobody here knows.

Note the site alongside the dose. If a local reaction appears three weeks later you will want to know where the previous four injections went.

If you are new and reading this thread for the answer to Completing a dose: the answer is conditional, the conditions are in the third reply, and the rest of the thread is worth skipping.

Worth separating two things that post #5 runs together.

The bit of Completing a dose that nobody enjoys is that the answer changes depending on what you are trying to decide with it. Say what the decision is and the thread will converge.

If you have to inject at a different time of day than usual, that is a much smaller perturbation than it feels for a weekly compound with a week-long half-life.

Adding this to the thread rather than to the wiki, because I am not confident enough for the wiki.

Completing a dose: I would want to see the raw numbers rather than the summary before agreeing. Summaries lose exactly the information that would settle this.

Narrowing post #9, because the general version has more than one answer.

A site rotation scheme that actually works: abdomen, outer thigh, back of arm, outer hip. Rotate through them in order, move a minimum 2 cm between consecutive sites, note the site with each dose. If a local reaction appears you have the history. If you rotate properly you will not get lipohypertrophy from overuse of one area.

I would hold that lightly until someone with a larger sample weighs in.

This settles it for me, at least until somebody posts a reason it should not.

Completing a dose 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.

If you have to inject at a different time of day than usual, that is a much smaller perturbation than it feels for a weekly compound with a week-long half-life.