Figuring out dose for Rocephin

[KuteNurse, LPN]

hello!

[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!

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[color=#ffa500]kn

[leslie :-D]

yes you would divide the amt. desired by the amt. you have on hand; so you would divide the 500 (amt desired) by the 350 (amt. available) which will give you the desired dosage, or 1.4 ml.

leslie

[The Sphynx]

1.4 mL sounds right. Call your pharmacy.

[mom23RN]

I agree that if you want to find how many mL the dose is that you can do the math. However, if you want the 500 mg that's what should be in the dose?? The vial is supposed to contain 500 mg. Now, that doesn' really matter how much you dilute it with, it should still be 500 mg??

[jetsetter]

It sounds like everybodys right; 1.4ml should be the dose, but it should also be the reconstitued amount you have.

[suzanne4, RN]

From a chemistry standpoint, the drug formulation is going to go into sloution, so you are going to have less mg per ml. Soem drugs are 1:1, meaning that they fully dissolve, and others do not. Unless you withdraw the entire contents and are using the full 500 mg, then you are going to have to calculate it based on the fomulation that the drug company gave you.

If you are going to be asked how much are you giving, you never answer the vial, and its contents; but the exact amount that you would be giving.

And that will be 1.4 ml, because of the drug expansion, or the way that the drug goes into solution would be another way of looking at it. But it is still going to be 1.4 ml, even if you are giving the complete contents.

In peds, you always answer with the exact amount that you will be giving, in ml, or however; not just the vial contents.

[KuteNurse, LPN]

Ok, Thanks for the info. But, what if the doc orders 1000mg IM? You obviously grab a 1000 mg vial. Reconstitute with 2.1 ml of lidocaine. Then you do your want over have. 1000mg/ml/350mg/ml=2.6 ml. Now...The medicine does expand, however, I have found that it is impossible to get 2.6 ml's from the vial. Is drawing up everything in the vial considered 1000 mg? Or, do you have to go to another vial and draw the 0.2 ml or so? That is where I get confused. And that is where we have conflicting issues about rocephin. Thanks

[suzanne4, RN]

What ius the factor for the dilution on the vial? I do not have the vial in front of me, but are they still using the 350 mg/ml? Many times it will change with the concentration.

[KuteNurse, LPN]

What ius the factor for the dilution on the vial? I do not have the vial in front of me, but are they still using the 350 mg/ml? Many times it will change with the concentration.

Yes....in a 1000mg vial of Rocephin, once reconstituted, there are 350mg/ml. The same as the 500mg vial.

[FP RN]

We are currently having the same discussion in our office. An email was just sent out stating that in order to give a patient one gram of rocephin, I need to use a one gram vial and reconstitute with 3.6 cc of 1% lidocaine as well as a 250mg vial and reconstitute with 0.9cc of 1% lidocaine. They state that we should give all of the medications (all four cc's) in order to give one gram of rocephin. This sounds like it would be 1250mg of rocephin? Does anyone know what the correct answer is if I want to give a patient one gram of rocephin?

[JanNP]

If you are using a 1 gm vial of Rocephin (powder), You can reconstitute with either lidocaine (plain), sterile saline or a combination of both to make the liquid mixture. You then agitate the mixture till it is homogenized and then draw out into 2 syringes ALL of the MEDICATION. You would be giving 500mg into each IM site, usually gluteus or deltoid, or thigh, so it will be 2 injections. It is just too much once rconstituted to give into one location.

Jan FNP

[PedsER-RN, BSN, RN]

yes, 1.4 ml is correct. that's how we calculate at my facility, also.

say you have a 500 mg vial and you want 400 and reconstitute with 1.5 ml lido. then you would draw up 1.2 ml (1.5 x 400 / 500 = 1.2).

if you ever have doubts check with pharmacy.