Figuring out dose for Rocephin

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

1.4 mL sounds right. Call your pharmacy.

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??

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

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

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.

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?

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

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.

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 :)