Using the 5mg pen for 2.5mg dose?

[SneakyLilNameChange]

hello- just about to start my Mounjaro journey as it were (BMI 32, really need to shed some weight). I got a good deal on a starter pack of 2.5, 5 and 7.5mg pens but have been reading loads of threads about people staying on the lower doses longer if needed. I have loads of needles that came with it- could I feasible just withdrew 0.3 effectively 10 times with the extra dose in when I go onto the second pen if I want to continue on 2.5? Thanks!

Well, you could, but the manufacturer instructions in the patient information leaflet says to dispose of the pen 30 days after you have first used it. Using a 5mg pen 8 or more times would mean using the pen well after the 30 days timescale. 5 uses fits within the 30 days ( days 1, 8, 15, 22 and 29), but you'd then be looking at days 36, 43, 50, 57 and 64. Each use increases the chance of contamination and bacterial growth, plus the medication itself may start to degrade and be less effective or possibly dangerous to inject.

You need to decide if you are willing to take that risk as no-one qualified will tell you it is ok. I would do a few days after 30 days to get another week, but after that I would consider it too high risk for all the reasons Silence has said.

We all know Mounjaro has very specific storage instructions to keep the medication stable and effective.

As soon you pierce the seal on the vial that first time the medication is exposed to air and the oxidation process starts, each time you use it there is the risk of contamination, regardless of how clean anyone thinks they are being we are using Mounjaro in domestic environment not a laboratory, there will be contamination and that may impact the stability of the medication over time.

There is no information available on what happens to Mounjaro once opened, how quickly it degrades, do chemical structures change and if new compounds are formed during that time are they harmful to inject.

Some use it well beyond the 30 day limit, weeks even, imo they are playing russian roulette not knowing if the gun is loaded.