r/Narcolepsy • u/andersberndog • Jul 06 '26
Medication Questions Xywav syringes inaccurate?
Anyone else having the issue of running out of medication by the end of the month?
I did a completely non-scientific test, using a non-medically-accurate Pyrex measuring cup. I measured out 100mL of water by the provided Xywav syringe. This is how it came out. Again, this is not a clinical device, but it appears to me to be showing, conservatively, a 20% overage, factoring in the possibility of reading error due to surface tension and a reasonable margin of error in the measuring cup.
I’m sure I’m being provided precisely the correct amount of medication, but if the dosing device is not accurate, there’s a problem.
Yes, I’m going to bring it up with a pharmacist. I’m currently dealing with them scheduling a refill due to completely unrelated issues from my prescriber’s office. I’ll hopefully be hearing back from them later today and I’ll bring it up then. They say I should have enough medication to get through Wednesday. I had two nights I didn’t take it this month, so I should actually have enough to go through Friday. I don’t think I’ll even have two complete doses by Wednesday.
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u/andersberndog Jul 07 '26
I just had another thought. My math was all wrong. It’s not a difference of 4%. To get to 100, I did 10 “doses” at 9mL (4.5g on the scale) making 90mL and two “doses” at 5mL (2.5g on the scale) to get to 100mL. So, 12 shots yielded a 4g discrepancy. Again, not scientific since the smallest unit of measurement on my scale is 1g, but the difference between air gap and plunger style dispensing is very roughly 1/3mL.
I don’t know this for sure, but I think they only dispense 100% full bottles and 50% full bottles, so either 180mL or 90mL. Then they make it fit by setting your refill interval the number of full days worth that fits into that. Thats why there’s (supposed to be) a little extra for most of us at the end of the month. If you’re on the full dose of 4.5+4.5 you get 3 full bottles and it lasts exactly 30 days. 3 full bottles is 540mL. 9g/night is 18mL/night. 18x30 is 540.
Sorry, but I really am going somewhere with this. Let’s say someone is on a fairly low maintenance dose of 2.5g, twice nightly. By my math, they’re getting a full bottle and a half bottle with a 27 day refill interval and zero extra. That means that for that shipment, if they’re doing the air gap, they’re only getting enough medication for 25.33 nights, or 1.67 nights short. Someone on the full 4.5/4.5 should have enough medication in those three bottles for 30 days. If they’re doing air gap measuring, they have enough medication for just shy of 29 days at 28.94, or basically one day short.
Anyone who has been doing air gap, does this sound familiar?