I was watching videos online and saw one claiming certain injection pens do not work well. I had bought two recently but had not used them yet, so I decided to test them. After mixing a batch I had supplies on hand. I filled an old cartridge with 3mL of plain water and loaded it into one pen. Trying to dose 20 units into a syringe gave only 14. Repeating the step after resetting the dial, a slow press delivered the full 20 units each time. The problem was pressing the button too fast.
Checking how well my injection pens actually dose
Summary
Do cheap injection pens deliver accurate doses or does pressing speed cause underdosing?
Users found that several low-cost pens delivered less than the dialed amount when the button was pushed quickly, but matched the setting when pressed slowly. Tests involved loading old cartridges with water and measuring output into syringes. Some mechanical pens later developed slipping or spring-back problems. A few participants noted that name-brand versions appeared more consistent, though all tested units came from similar online sources.
What this discussion establishes- Fast button press on certain pens resulted in only 70% of the intended dose
- Slow, steady pressure made the same pens deliver the full dialed amount
- Mechanical failure appeared in some units after a few months, with the plunger slipping or rebounding
- Testing by back-filling an insulin syringe was preferred over weighing
- Even some higher-priced pens showed pressure sensitivity while others did not
Whether to keep using tested inexpensive pens or switch to brand-name models for reliability
Still openHow long any of the pens will continue working without developing mechanical issues
Nothing here is advice.
25 replies · 13 people
↳ replying to @ClearBeacon24
It really was not much work, and it is not something I plan to repeat.
Huge gratitude for your experimentation here and solving the correct operation method! 💕
↳ replying to @WarmQuill37 (opening post)
Appreciate it! Wondering what technique you used for getting the closures to settle lower inside the previously used container until it reached a three milliliter volume. I'd like to experiment with that approach.
↳ replying to @ClearWillow59
The pressure from adding the water did that. Try it yourself.
I bought ten v2 pens online and they have been junk. In the tests the pink one is a v2 clone, the orange one is another online version, the blue one is a brand-name model, and the maroon one is another brand-name model.
That's fascinating and I appreciate the details shared here. Came across a mention from an RS discussion noting that slow pressing on those low-cost manual devices during use improved their precision. It looks like the approach involved transferring contents straight into a syringe designed for insulin. Ended up landing in this spot after the site directed me here under the impression it was a fresh discussion.
↳ replying to @WarmCompass17
Definitely the version two pens from my purchase outputted unequal quantities according to the speed at which they got pressed. Sadly one additional pen without any picture varied by up to half too low or half too high based on the force. The remaining ones stayed the same.
↳ replying to @SharpCompass19
That's interesting information indeed. I should probably check the pens we have here ourselves, though purchasing branded items could be preferable when available. How did you come across the reliable ones?
I bought brand-name pens from the maker, no trouble with them.
↳ replying to @WarmCompass17
Every pen there is from the same online source.
↳ replying to @SharpCompass19
I somehow did not expect that answer. Thank you.
↳ replying to @WarmCompass17
I think he means the inaccurate pens are from that source.
My V1 pen let me measure out 25/50 units which I then pulled into a U100 syringe. The amount matched perfectly. This approach seems better to me than relying on scales.
I'm thinking about trying those pricier branded devices to check if quick button presses might still cause wrong amounts like the budget version did. At the same time another injector really isn't needed here. Already have two inexpensive models along with four more that were probably obtained the same way. Not sure though maybe just adding one extra.
↳ replying to @BrightMeadow15
There are sellers of the brand-name pens on the same site. They have not-for-resale markings on the boxes, so I assume they come from some bulk program. They are usually listed around eighteen dollars.
↳ replying to @SharpCompass19
Yeah, that checks out. Sometimes those turn out to be an older version from the same company, the way an earlier item came ahead of the newer one. My attempts to look them up don't usually turn up much.
This brings back how those five pens bought online several months earlier turned out unreliable, since the plunger pops back near the finish of any injection past about ten units. The versions holding my current compounds are the basic models, and I figure I'll pick up another pair. I won't need the full number I've got on hand now that I'm quitting the habit of stacking extra non-glp1 items together, so two extra ones will cover everything. That leaves me ready for a round of one compound or the other, plus in case I want to repeat the mitochondrial treatment with nad and whatever else goes with it.
↳ replying to @SharpCompass19
My novo pen won't work with the regular cartridge without using an adapter first.
↳ replying to @SteadyQuill55
Maybe the problem stems from resistance building because the tip got blocked or isn't large enough for the stuff coming through. Have you tested releasing it more gradually or keeping pressure applied for extra time?
↳ replying to @QuietAnchor73
It was not a force thing; it was like the plunging mechanism was slipping a gear.
↳ replying to @SharpCompass19
That's odd. Over here in the States almost every one of those pulls up the matching pen right away but then a big popup appears saying they aren't offered for sale in my region or close to that.
↳ replying to @SteadyQuill55
Same thing happened with mine. It would snap backwards every time, which threw off how much came out next. So I just got rid of it.
↳ replying to @PlainTimber78
I agreed with the point. Thought about hanging on to them but then wondered what sense it made to hold a tool that failed to operate right. So I tossed those out and picked up a couple replacements, leaving me set. Four items cycling through covers everything I need anyway, including those three along with one other. Any time it crosses my mind that extra shots would be required together, it turns out that's not true.
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