Pen Issues: First Dose Off?

BrookEdit

BrookEdit

Well-known member
Hey all,

Anyone else run into this weirdness with their pens? I'm using V1 pens and trying to check the dose accuracy. I stick an insulin syringe in, dial up the dose, and push the plunger. Then I compare what I dialed to what's in the syringe.

Here's the odd part: the *first* time I do this with a pen, it consistently underdoses. But if I try it again right after, even with a tiny dose like 2 units, it's spot-on. Every single time.

Steps:
1. Load cartridge.
2. Attach a fresh needle, dial until the plunger touches the stopper and a bit of liquid comes out.
3. Dial to 2 units, flick to remove any air, then inject. Seems perfect.
4. Remove needle, insert insulin syringe.
5. Dial a higher dose (20, 60, 80 units), hold steady, and inject into the syringe. It's short!
6. Dump the liquid, reinsert the syringe & retry 20 units. Perfect now.
7. Try 2 units, 5 units, 10 units... all accurate.

It's like the initial dose is always off. This happens with all 4 pens I've tried. I prime them correctly, so I'm baffled.
 
Are all your pens the V1 version, or do you have any name-brand ones to compare? I'm not saying V1/V2 is bad, but the build quality might not be the same as a brand-name pen. I haven't tested mine yet because I hate wasting a cartridge just to check. Maybe I should buy some cheapies to test?
 
I’ve got four V1 pens from a vendor and one authentic Lilly Luxura. The Luxura was acting weird, with inconsistent dosing, which is why I got the others.

I can't figure out why the first dose is always inaccurate. I'm using insulin needles (fixed needle, very low dead space), so it’s not that, otherwise it wouldn’t measure correctly the second + times. And I'm priming to eliminate air.
 
Just a generic one. I'm starting to think the plunger's initial movement is off, but once it gets going, it's accurate after that? It's weird because you would think it would be inaccurate further into the cartridge too!
 
Update:

I tested all four V1 pens and the Lilly Luxura, with a real Lilly cartridge and a generic one. I even had a friend help to see if it's me. Same problem: underdosing on the very first dose. Really odd.
 
I could, but I think there's something going on here that other people just haven't picked up on yet.

It seems suspicious that it's happening to me and my friend, with cartridges from different makers and pens from different makers. We've eliminated so many possible errors, and it's still happening.
 
This is quite intriguing. Assuming your testing method is consistent, that initial under-dosing suggests a potential mechanical issue. Perhaps the initial pressure required to overcome the cartridge's seal or the plunger's stiction is higher, leading to the discrepancy. Once that initial barrier is overcome, subsequent doses behave as expected. Has anyone tried contacting the manufacturer for insights?
 
Yo, @BrookEdit, that's wild! Reminds me of when I first started on sema. I was using those pre-filled pens, and I swear the first few clicks never seemed to do anything. Then BAM, it kicked in. Maybe it's just the pen getting primed or something?
 
Interesting findings, @BrookEdit. Have you considered that the issue might be related to the viscosity of the solution and the internal diameter of the needle? A higher viscosity might require more initial force to initiate flow, especially when the pen hasn't been used for a while. This could explain the first dose discrepancy. Also, are you storing the pens horizontally or vertically? Storage position can sometimes affect the concentration of the medication within the cartridge.
 
I've been using the same pens for a few months now, and I've found that click counting can be a real money-saver. I was on 0.5mg weekly, but my doc upped me to 1mg. The 1mg pens have 4mg of product, but only 4 doses. So, if you're careful, you can dial half doses by counting clicks and get a full 8 weeks out of each pen. Just make sure to keep it in the fridge!
 
StallStopper said:
I've been using the same pens for a few months now, and I've found that click counting can be a real money-saver. I was on 0.5mg weekly, but my doc upped me to 1mg. The 1mg pens have 4mg of product, but only 4 doses. So, if you're careful, you can dial half doses by counting clicks and get a full 8 weeks out of each pen. Just make sure to keep it in the fridge!
Click to expand...

While click counting can be cost-effective, it's important to emphasize the potential for dosing errors. Patients should be thoroughly educated on proper technique and understand the risks involved. Also, remember that the manufacturer typically recommends disposing of the pen after 56 days of first use; using it beyond that timeframe may compromise the medication's efficacy and sterility. Proceed with caution!
 
ChicagoChonk said:
So, I just got my stuff delivered... but I'm a bit confused. I thought I'd get pre-filled syringes, but instead I have a bunch of empty syringes and a vial! What do I do with this? I don't see any instructions.
Click to expand...

Don't panic! It sounds like you've received a compounded formulation. Look closely at the vial. It NEEDS to have a concentration listed (like 2.5mg/ml). If there's no concentration, contact the provider IMMEDIATELY. Do NOT inject anything until you know the concentration and how much to draw into each syringe. You don't want to accidentally overdose!
 
The Zepbound pen has a glass vial and sturdy plunger inside, way different from a cheap insulin syringe. The green piece activates the spring. All quality parts. Can't speak to multi-use pens generally but the engineering is solid.
 
Oof, I relate to this so hard. Was getting ready to inject, cap off, unlocked it, and down it went. Direct hit to the floor meant my whole dose vanished into the carpet. Those pens have a super sensitive trigger. Now I'm a week ahead on my schedule and it's going to be rough. The waste alone hurt.
 
Where are you located? Can you share a photo showing the pen strength or just tell us which one you have? That's what determines the dose amount. The red US pen is 0.68 mg/mL with 0.01 mL per click, so each click is 0.0068 mg. If you got 37 clicks, that's about 0.252 mg total.
 
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