Help! At my wit's end with reconstituting a med

[flyingchange]

I can't take it anymore. I have wracked my brain trying to figure out the math or even best practice on this issue. In desperation, I turn to you, o mighty nursing think tank!

Behold, the most baffling med math I've ever seen:

My homecare patient gets an uncommon drug in a weekly infusion. To keep me slightly more anonymous, and for ease of readability, we shall call it MiracleDrug ™. The order: Infuse 4 grams of MiracleDrug IV over 30 minutes every 7 days. My patient gets 4 vials shipped to his home every week for me to infuse.

Easy, right? Here's the problem. MiracleDrug is not a standard 1 gram per vial. Depending on the lot number, it can be 1100 mg or more per vial.

MiracleDrug comes with 4x20 mL vials of sterile water to reconstitute into. Per the drug insert, I use a transfer needle to put all of the diluent in the MiracleDrug. Simple, straightforward med math means that I draw up, say, 65 mL of reconstituted drug to make 4 grams.

The problem is that there is quite a bit of MiracleDrug powder in each vial, so when I reconstitute it, each vial contains probably 25-30 mL altogether. But unlike most meds, there isn't an insert to say "add 18.7 mL sterile water to equal 20 mL of reconstituted medication at a concentration of 58.4 mg/mL". Instead I'm adding 20 mL to equal an unknown volume.

So sometimes, when I've tried to do this properly, I end up drawing up all my required volume out of only 3 vials, leaving the 4th untouched! That means the patient would only be getting 3.3 g of MiracleDrug instead of 4 g.

Anyway, I've tried to escalate this issue every way I know how. I've emailed the MiracleDrug supervisor at my company. I've called the pharmacy for help. I've called the drug company for help. I've called the prescribing physician's office at least 4 times. If I could just get the physician to change the order to "4 vials q weekly", I'd be okay.

But alas, nothing. Either people don't know, or they don't care, or both. Obviously, I care a lot, because I want my patient to receive the proper dose and stay healthy, and because it's my ass on the line if he develops complications from being chronically over- or under-dosed.

Until this situation gets resolved somehow, I've decided to just give him the contents of all 4 vials, which can be up to ~4.6 grams altogether. I've charted everything so far including all the phone calls and emails I've sent about the issue. I get the feeling that there MUST be other colleagues giving this med without asking these questions. But now that I've uncovered the issue, I can't "unsee" it.

Nurses, can you help me? Perhaps you can point out something I'm missing in my med calc, or help me figure out how to gracefully handle this issue without losing my job or my licence.

[LoveMyBoxer99]

Would love to help, but I am at a complicated loss as well. The answer would be very interesting, so please update if you figure it out.

Good luck!

[blondy2061h, MSN, RN]

So you have a known amount of drug in each vial, correct? And my understanding is that you're injecting 20ml of diluent into each vial. I would get a 30ml syringe if you can find one and draw up all of the drug from the vial after the diluent is added to get a total volume. Then you will know it's 1.25 grams per 25ml or whatever and be able to figure out the needed volume. Are all 4 of the vials the same dose? You make it sound like he's not getting the same drug dose delivered each week.

[roser13, ASN, RN]

I infuse my husband weekly with our version of MiracleDrug. I think the confusion may stem from the assay of each vial. Our MD is derived from a plasma donor. Depending upon the plasma, the assay result may vary.

What I have found is that the MD manufacturer will package the vials together for one dose. Those vials are unfailingly of the same assay amount, thus the dose comes down to how many vials of x assay = the proper dose.

Also of note: All reconstituted drugs hat I have ever dealt with carry a dosage which is +/- X%. That percentage usually covers quite a wide range of actual drug infused.

My guess from afar is that your MD manufacturer is packing together 4 vials with assays that constitute your patient's correct dose.

[roser13, ASN, RN]

" But unlike most meds, there isn't an insert to say "add 18.7 mL sterile water to equal 20 mL of reconstituted medication at a concentration of 58.4 mg/mL". Instead I'm adding 20 mL to equal an unknown volume."

I may be misunderstanding, but I think your reasoning here is incorrect. If I add 20 ml sterile water to X dry ingredient, I end up with 20 ml fluid, regardless of the quantity of dry powder. So the mg/ml will always be the published grams/20ml, an easy division down to gram/ml.

Are you by any chance confusing reconstitution with dilution of a liquid med?

[blondy2061h, MSN, RN]

Adding powder to a liquid does increase the liquid volume in the end.

[roser13, ASN, RN]

After I wrote that I wondered if I was 100% correct about it. Do you know much (percentage-wise) it increases? Guess it might depend upon the quantity of powder.

Adding powder to a liquid does increase the liquid volume in the end.

[blondy2061h, MSN, RN]

Yep, depends on powder amount. This is the issue the OP is having.

[roser13, ASN, RN]

Yep, depends on powder amount. This is the issue the OP is having.

But if the grams are consistent/measureable, the fluid volume shouldn't matter.

[blondy2061h, MSN, RN]

She needs to give a 4gm dose and the vials are slightly more than 1 gm each so for at least one of the vials she needs to know the concentration because she isn't going to give the full vial.

[roser13, ASN, RN]

She needs to give a 4gm dose and the vials are slightly more than 1 gm each so for at least one of the vials she needs to know the concentration because she isn't going to give the full vial.

But the +/- % differential may make a difference and simplify the whole equation.

[Clovery]

Get a scale and measure out 4 grams and then reconstitute it.

Or just do the math... for example if you have 1100 mg in 20 mL of water then you have 55 mg/mL. If all the vials are different then do the math for each vial in the 20 mL of water and add them together until you have 4 g in an unknown amount of water. The amount of water doesn't matter, only the amount of the drug.

So lets say you have 4 vials, one is 1000 mg, one is 1100 mg, one is 1200 mg, and one is 900 mg. Each comes with 20 mL water.

1000 mg/20 mL = 50 mg/mL. put the full 20 mL in the bag, you now have 1 gram (1000 mg)

1100 mg/20 mL = 55 mg/mL. put the full 20 mL in the bag. you now have 2.1 g (2100 mg)

1200 mg/20 mL = 60 mg / mL. put the full 20 mL in the bag, you now have 3.3 g (3300 mg)

last vial... 900 mg/20 mL = 45 mg/mL. you need 700 mg to make a total of 4 grams... 700/45 = 15.56 so put 15.5 mL of this solution in the bag and you are at 4 grams of miracle drug in 75.5 mL of water.

Your order isn't for a volume of fluid, it's for the amount of drug in an unknown amount of fluid. add the drug to the given fluid and then figure out what your total volume is and infuse it at the ordered rate.