# Unasyn dosing question

1. Hello,

I am new to this site and am seeking some learned opinions on an issue that came up during a clinical rotation today.

I am a student nurse going through a pediatrics/obstetrics rotation at Harbor/UCLA Medical Center. I was caring for a young man S/P soft tissue injury who was recieving Unasyn 1gm IV Q6hrs. The order said, verbatim, "Unasyn 1gm IV Q6." As you doubtlessly know, Unasyn is an ampicillin/sulbactam combination. Pharmacy provided the Unasyn in a vial containing 1 gram Ampicillin and 500 mg sulbactam, making for a total of 1.5 grams of Unasyn. The drug guide reccomended that it be diluted in 3.2 ml of sterile water, making for a concentration of 250 mg Amp and 125 mg sulbactam per ml. When doing the calculations required by my instructor before administration, I calculated the amount to draw up to yield one gram of total medication, ampicillin and sulbactam combined. This neccessitated 2.666 ml to be drawn up. My instructor insisted that I calculate for one gram of total ampicillin activity, which required 4 ml to be drawn up (the entire vial). I doubted this, since the order was for 1 gm of UNASYN, not ampicillin, and giving the entire vial would really give 1.5 grams of Unasyn. Moreover, the amount that pharmacy reccomended I draw up agreed with my calculations perfectly: 2.666. When I asked an RN working on the floor, she said she agreed with me: draw up one gram of both medications.

Can anyone say which is the proper method? I still believe that prescribing one gram of Unasyn means one gram of both medications, not one gram of ampicillin.

Eric
Last edit by shtinkypuppie on Sep 22, '06
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3. http://www.rxlist.com/cgi/generic2/unasyn_ids.htm

Check out this website and see if that gives you any answers.
4. I'm currently a inpatient hospital Pharm tech (about 5years now), soon to be RN student. Your calculation sounds correct to me. Combination drugs are usually only dosed upon one component. Unasyn being a combination drug, is only dosed upon the ampicillin component. One question I have for you, why didn't pharmacy prepare this?
Last edit by MiRnSoon on Sep 22, '06
5. Quote from MiRnSoon
One question I have for you, why didn't pharmacy prepare this?
Some places, like mine, have nursing staff reconstituting meds.
6. If in doubt, you'd have to check with the prescribing physician as to his intention, but as ordered, you were correct. If he ordered 1g of the total preparation, you were exactly right.

I do think docs should order these combination drugs as the total amount of both components desired eg. 1g ampicillin/500mg sulbactam, rather than a trade name, for clarity.
7. WOW...I am so glad ours comes in already done by pharmacy! These IV bags have NS in them, then there is a vial of premixed on the top...you just fiddle around and pop the stopper (which is inside the bag...very easy) and shake it..done!

I love having a great pharmacy team! It has cut down errors tremendously!