Last Pen Dose?

Thanks, that's a good idea. Will the plunger still work afterward though? I prefer using my small pen needles.

That's clever.

Right? My husband said just to toss the last bit so I wouldn't risk getting a short dose, but I figured someone here would have a better suggestion.

You can push it back in, but that defeats the point. You can usually pull the last little bit out of the cartridge with the syringe anyway. There's always some left after the plunger stops moving.

This also looks like a reasonable way to test whether the pen is delivering accurate units. Just insert the syringe needle, dial, push, and check the volume. It's simpler than trying to attach a needle and push into another syringe.

It works for that too. It's also useful for getting rid of that last stubborn air bubble.

Update: won't be trying that again. The stopper moved up unevenly and some liquid leaked out the bottom. It's only a small loss since I only have a few days left on this cartridge anyway, but I would have been upset if it happened with a full cartridge of something longer-lasting.

I'm not sure how you managed to do that.

No idea. The only thing I can think of is that I didn't insert the syringe right in the center because I didn't want to damage the area where the pen needles go. That might have made the pressure slightly uneven when I pushed. Just a guess though.

Sorry if I misunderstood, but did you insert the insulin syringe into the cartridge and then, without pressing on the syringe plunger, dial the pen to see whether the clicks matched what the pen delivered? Rather than pushing anything into the cartridge while the pen plunger was still engaged. Being near the edge of the rubber shouldn't matter; I do that all the time.

I worked the insulin syringe plunger back and forth a couple of times without taking the cap off to loosen it up a bit. Then I pushed it all the way in, dialed the pen twenty clicks, put the needle into the cartridge near the edge, and pressed the pen to inject. I got twenty units in the syringe, thought it worked, injected it, then picked the pen up and saw liquid around the bottom of the cartridge. The stopper was slightly tilted. I wiped inside the cartridge, put it back, attached a pen needle, and wasted a few units to check if the stopper would straighten, which it seemed to. I agree it shouldn't have happened, but it did.

My stoppers are often slightly tilted; the plastic plunger can go off center easily. Maybe that particular stopper wasn't perfectly round and leaked on its own. These things are mass-produced and some probably shouldn't have passed quality control.

Different pens act differently. Some won't let you dial past the remaining amount, others stop at whatever is left. Either way it's helpful and tells you how to finish with the next cartridge. The markings on the cartridge itself are not accurate.

That's actually the method Peptide Critic recommends for checking pen accuracy, and it's how I found out my Amazon pen was inaccurate. I will admit I've done the opposite of what people here are doing: instead of pulling the last bit out, I used a spare reconstituted vial and a 3 ml syringe to push liquid back into the cartridge while it was still in the pen.

When the plunger is pushed down the cartridge is open to the air and no longer sterile. Refilling it and pushing the plunger back out is a reliable way to contaminate the cartridge. I would advise against doing that.

I didn't know until I finished my first cartridge. I'm glad it shows the shortfall so I don't have to worry about missing part of the dose. Not every pen may do this, so it's helpful, especially for someone new like me. I started this thread because I knew the cartridge was getting low and had no idea what would happen.

I get that. That's the reason I began my comment by confessing to having done so. I'm not suggesting anyone else try this. It happened as an immediate response after receiving just part of the amount when the device emptied. I recognize the potential danger involved. This danger seems smaller than the possible bacterial contamination in my substances prior to starting purification a few weeks ago. I'm fine with the choice.

I wanted to make sure everyone else understood the risk too. Filtering and avoiding refilling cartridges are the safer approaches.

To be precise, if you didn't push the cartridge stopper back far enough that the exposed area went back into the fluid chamber, it might still be okay. You can only do that once though. Instead I suggest pushing some air into the cartridge and pulling the remaining solution out with a syringe so you can use it. Part of me hates seeing the few units still stuck to the sides go to waste.