[color=#ffa500]this color looks like squash! lol i was trained in pediatrics to figure out the dose of rocephin a conflicting way. on the back of the bottle of rocephin, the bottle says that once reconstituted with lidocaine, the medicine expands and becomes 350 ml/mg. i was taught in peds to do your want over have, for example:
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[color=#ffa500]the doc orders 500 mg rocephin im. ok, so i grab the 500 mg vial of rocephin and reconstitute it with lidocaine. i do my math: want-500 mg/have-350 mg/ml. now i would think that just reconstituting the vial and drawing all the medicine up would be 500 mg. but, where i work, they are saying you have to divide 500/350 and that will give you your dose. the answer is 1.4 ml. this is confusing to me. i would like some input on calculating this dose. thanks!
Just curious to know how other nurses are drawing up ceftriaxone (rocephin):
So if we have a gram vial, that states after reconstitution the strength is 350/ml, we just divide the desired dose by 350 right?
What if you need a dose of 1000mg? That should be 2.8ml to be drawn up. If you can't get a full 2.8ml out of the vial, do you grab a 250mg vial and get the rest of the amount you need?
So say I am able to draw up 2.6ml. That equals 910mg based on the given strength of 350/ml. I am still needing 90mg. If I grab a 250mg vial I would need to draw up 0.36ml to give me 1000mg. Is that correct?
I know that some nurses would just draw up the total volume into the syringe, and then use that volume to calculate the dose to draw up. So, if they drew up 2.6ml they would take dose desired 1000mg divided by volume on hand 2.6 and then multiply by 1000 again. According to manufacturer's directions that is not the proper way to calculate the dose due to margins of error, chemistry of medication etc. However that way does make sense.
So I am just wondering how others draw up IM ceftriaxone.
I did speak with a pharmacist and they did state if you are not getting the amount you need, the mixture needs more mixing, time to dissolve etc. Do others usually get the proper amount out of the vials? Is not getting the right amount due solely to improper mixing of the medication? I do not have the opportunity to give IM ceftriaxone a lot to really see what the final volume ends up being, but there are people who swear you never get the 2.8ml you're suppose to get if you have a gram vial.
Wow,..I don't work in peds,..but either you guys are making this way too difficult or I've been doing it wrong for 15 years! If the vial says 500mg,.it doesn't matter if I mix it with 2cc or 10cc if I use the whole vial I have 500mg,..half the vial 250mg,...I will often decide how to dilute the vial based on how much I need to give,..ie,.if it's a child that needs 250mg IM I'll dilute the 500mg with only 2cc and give 1cc,..a smaller vol to inject.,..if it's a big adult I'll mix it with more just because it's easier/quicker to get it all disolved.
can i just say that the best part of this post was the very first line, that the color of your font looked like squash lol i guess i just was not expecting that when i went to read it. so it kinda made my night haha thank you
Wow,..I don't work in peds,..but either you guys are making this way too difficult or I've been doing it wrong for 15 years! If the vial says 500mg,.it doesn't matter if I mix it with 2cc or 10cc if I use the whole vial I have 500mg,..half the vial 250mg,...I will often decide how to dilute the vial based on how much I need to give,..ie,.if it's a child that needs 250mg IM I'll dilute the 500mg with only 2cc and give 1cc,..a smaller vol to inject.,..if it's a big adult I'll mix it with more just because it's easier/quicker to get it all disolved.
Often when you reconstitute you end up with a larger volume...so basically, no that's not correct. You need to dilute and withdraw based on the guidelines on the bottle if you're giving a partial dose...
Often when you reconstitute you end up with a larger volume...so basically, no that's not correct. You need to dilute and withdraw based on the guidelines on the bottle if you're giving a partial dose...
I'm confused then,...if the vial says it contains 500mg,.it shouldn't matter how much I dilute it with. The entire volume is 500mg,.half of the volume is 250mg,...if I add 3cc and the total vol is 3.5cc then that should be 500mg and half of it should be 250mg,...unless there really isn't 500mg in the vial.......
But, what is the purpose of giving the instructions to dilute with the labeled amount of diluent if the resulting volume isn't what is needed? That is another reason why I was asking if other healthcare professionals have the issue of ending up with the volume needed after reconstitution.
I'm confused then,...if the vial says it contains 500mg,.it shouldn't matter how much I dilute it with. The entire volume is 500mg,.half of the volume is 250mg,...if I add 3cc and the total vol is 3.5cc then that should be 500mg and half of it should be 250mg,...unless there really isn't 500mg in the vial.......
The full vial should be 500 mg. As a pharmacy tech, we always just withdrew the whole bottle...However, if you are doing as said before and diluting with 2, withdrawing 1 mL, you're not accounting for the extra amount. Depending on the drug, there can be a lot or very little difference in the final volume, therefore a significant difference in the dose you're giving. It's difficult to determine partial doses and they're carefully calculated by drug companies, so it's best to go as directed. For example, one time a doctor ordered a partial zosyn dose for a kid. There were no directions for partial doses and final dilution concentration, so the pharmacist called the manufacturer. They told us they had no information on what the final concentration would be and therefore we couldn't accurately give a partial dose. The doctor then had to switch antibiotics. Also, if you dilute with less, you're risking not fully diluting the drug...just because there aren't visible chunks doesn't mean there aren't small undissolved particles. Drugs vary, so it's always best to check with the pharmacist...
But, what is the purpose of giving the instructions to dilute with the labeled amount of diluent if the resulting volume isn't what is needed? That is another reason why I was asking if other healthcare professionals have the issue of ending up with the volume needed after reconstitution.
In my experience making IVs, I never had an issue with the final amount. Like your pharmacists told you, perhaps it's not being fully dissolved? Also, make sure you're getting all of the liquid out of the syringe you dilute with. Also, larger syringes are less accurate, so if you're using a bigger one, that might have some bearing on your final amount. If there's any foam or droplets in the bottle, you'd be surprised how much volume that can account for as well. If you have it tipped upside down when you're withdrawing some of the liquid sometimes sits around the plug, try turning it over and getting the rest with the needle. One vial (of things that need to be reconstituted, not premixed drugs as those always contain overfill) should contain the amount stated and the only reason I can think of getting a second is it's hard to get everything out sometimes. If all else fails, go make one of the pharmacists or techs show you how they're doing it, maybe it can help? I absolutely don't think you're doing anything wrong, I just never had the problem you're having and I made a ton of IVs and we made all of the IM injections for peds and sent them up in syringes... Our nurses were never supposed to be mixing anything (unless it was stat and we were gone, new orders that absolutely had to be started before we got there, or drugs that lose their stability too quickly for us to premake for the overnight shift) and I honestly hope that's the case when I go to work. I just want to say, a lot of drugs are different, so just make sure you check with the directions and/or pharmacist.
In sum, a full bottle should be a full dose but the final concentration and therefore the calculations given are also correct. Both parties are basically right, it's just a matter of getting everything out of the bottle and mixing it well enough...
Yeah it is kind of confusing. Logical thinking is if it is a gram vial, then that is how much is in the vial. But, then the manufacturer has a strength per ml labeled. After reconstitution co-workers of mine never get the final volume that it should be based on labeled strength. So, that interferes with how to figure amount to draw up for injection lol. txhorns10 thanks for your response. It was helpful. Do you know how long it should take for a medication like ceftriaxone to be fully mixed? Or an approximate idea?
snoopyzspotz87
3 Posts
Just curious to know how other nurses are drawing up ceftriaxone (rocephin):
So if we have a gram vial, that states after reconstitution the strength is 350/ml, we just divide the desired dose by 350 right?
What if you need a dose of 1000mg? That should be 2.8ml to be drawn up. If you can't get a full 2.8ml out of the vial, do you grab a 250mg vial and get the rest of the amount you need?
So say I am able to draw up 2.6ml. That equals 910mg based on the given strength of 350/ml. I am still needing 90mg. If I grab a 250mg vial I would need to draw up 0.36ml to give me 1000mg. Is that correct?
I know that some nurses would just draw up the total volume into the syringe, and then use that volume to calculate the dose to draw up. So, if they drew up 2.6ml they would take dose desired 1000mg divided by volume on hand 2.6 and then multiply by 1000 again. According to manufacturer's directions that is not the proper way to calculate the dose due to margins of error, chemistry of medication etc. However that way does make sense.
So I am just wondering how others draw up IM ceftriaxone.
I did speak with a pharmacist and they did state if you are not getting the amount you need, the mixture needs more mixing, time to dissolve etc. Do others usually get the proper amount out of the vials? Is not getting the right amount due solely to improper mixing of the medication? I do not have the opportunity to give IM ceftriaxone a lot to really see what the final volume ends up being, but there are people who swear you never get the 2.8ml you're suppose to get if you have a gram vial.
Thanks for anybody's input :)