Help with a drug calculation problem

Nursing Students Student Assist


Hi Everyone,

My nursing school is having us take a math competency test and they gave us some practice problems to help prepare us. I managed to do most of them just fine, but there is one in particular that is giving me a hard time. Here it is:

Order: Ancef 1g/50ml IVPB Q4H, infuse over 30 minutes.

IV tubing is labeled 20 drops/ml.

Calculate the flow rate in drops per minute for this antibiotic.

Does anyone know how to solve that? I am completely stumped. Any help would be greatly appreciated! Also, if you have had to take a math competency exam, how hard was it? Thanks in advance for your response!

If I am not mistaken I think the formula for this problem is

Amount to be infused x's the drop factor/ the time of infusion in minutes.

I thiiiink that is the formula

That, indeed, is the formula!

So not to sound stupid or anything, but how exactly would you go about using the formula? I've never used it before =(

Let's break it down. We're beginning with the amount to be infused. You are giving Ancef 1g/50mL. This means that there is one gram of Ancef (an antibiotic) dissolved in 50mL of solution. So, the amount to be infused is 50mL.

Next, you are multiplying that by the drop rate of the tubing. That rate is 20 drops per mL.

Next, you divide your product by the number of minutes over which the medication is to be infused. According to your problem, that number is 30 minutes.

So you have 50 x 20 / 30 = ? For drops per minute remember to round to the nearest whole number.

Thank you so much!!!!!! That is indeed the answer! I had just been trying to use a conversion method this entire time (considering the test is just supposed to be on math competency and we haven't even learned this method yet)! Thank you! I sure hope they don't have any of those problems on the test! Once again, thank you!!!!

One of the common problems I have seen when students ask for med math help, is they have gotten bogged down with all the numbers in the question.

yOUR questIon is: Order: Ancef 1g / 50ml IVPB Q4H, infuse over 30 minutes. IV tubing is labeled 20 drops/ml. Calculate the flow rate in drops per minute for this antibiotic. Lots of numbers to consider.

So we have 1 gram of Ancef in 50 mL and it is to infuse over 30 minutes. There is a drip/tubing of 20 gtts (drops) per 1 ml

The answer will be a flow rate, but the flow rate would be mL per minute NOT grams (or mg) per minute. This is an important concept to rembmber. mL = liquid and grams = weight. It would be impossible to administer a weight through a tubing or a pump. That is why your answer would be mL.

Another concept to remember: If the question is applying a drip chamber/tubing, you will NOT use a pump. The rate for the IV administration without a pump employing a drip chamber will be in mL per minute.

If the IV were employing a pump, there would be no drip chamber. The answer would be in mL per HOUR

Specializes in ortho, hospice volunteer, psych,.

When you do take the test, try not to panic because that will just make the test harder. Keep

telling yourself formulas make it easier. Memorizing a few formulas before the test, means that

they become automatic, instead of having to stop and remember which formula goes with which

kind of problem.

Well worth the effort and good luck on your test!

Specializes in Critical Care, ED, Cath lab, CTPAC,Trauma.

Thanks@ Esme12, I bookmarked that site, I think I will find it very helpful in my future.

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