dosage problem...need help

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Sorry guys, but going through some examples our instructor gave us and am having some difficulty. I may have to post more later on.

1) 0.9 gm of Cordarone in D5W has been prescribed for IV infusion at a rate of 0.5 mg per minute. The IV solution has a total volume of 500ml. The IV should be infused at how many ml per hour?

2) An IV of D5W containing 2 mg of epinephrine and a total volume of 250 ml is to be infused at a rate of 15 mcg per minute. At how many ml per hour will you infuse the IV.

3) An IV of D5W containing 2 mg of Isuprel and a total volume of 250ml is to be infused at a rate of 1 mcg per minute. At how many ml per hour will you infuse the IV

I am sure I am just looking to far into this, but it is just not making any sense to me.

Specializes in Geriatrics/Family Practice.

1) 0.9 gm of Cordarone in D5W has been prescribed for IV infusion at a rate of 0.5 mg per minute. The IV solution has a total volume of 500ml.

The IV should be infused at how many ml per hour?

Just use your calculator and do exactly as I do below.....

Take what you want 0.5mg divided by what you have 900mg (0.9g) multiplied by the volume.

Ex: 0.5 divided by 900mg (0.9gm) X 500ml =.28mg X 60min/hr=16.66

want have volume

or 7ml/hr.

2) An IV of D5W containing 2 mg of epinephrine and a total volume of 250 ml is to be infused at a rate of 15 mcg per minute. At how many ml per hour will you infuse the IV.

Alway convert first: 2mg=2000mcg

Ex: 15mcg divided by 2000mcg X 250ml =1.875ml/min or 2ml/min

want have volume

3) An IV of D5W containing 2 mg of Isuprel and a total volume of 250ml is to be infused at a rate of 1 mcg per minute. At how many ml per hour will you infuse the IV

Convert 2mg=2000mcg

Ex: 1mcg divided by 2000mcg multiplied by 250ml= .125ml

want have volume

X60min/hr=7.5ml

This is the way I was taught to do calculations in pharmacy when I worked there. I work as a LPN now so I do not do these type of calculations anymore so I hope there all correct. But we just used a very simple formula.

Dose you want divided by have (stock) mulitiplied by quantity/volume.

Always convert to the same mg/mg or mcg/mcg, etc.

Good Luck

Specializes in Med Surg, ER, OR.

Thanks KSTEC for your post. That does make sense, but with the second problem, I saw that the answer wasn't correct. Answer should have been 113, but yours was 120ml/hr. I think I will probably stick with the first method that melody in my heart had. Just seems easier to me, and we know that is what you have to do when you get out on your own.

Specializes in Geriatrics/Family Practice.

The second questioned ask per min not per hour which does come out to 1.875ml/min or 112.5/hr. Because I'm a LPN and do not do program IV's pumps I just rounded up to 2ml/min. Thanks for you input, I've always wonder if my method was easy or hard.

Specializes in being a Credible Source.
The second questioned ask per min not per hour which does come out to 1.875ml/min or 112.5/hr. Because I'm a LPN and do not do program IV's pumps I just rounded up to 2ml/min. Thanks for you input, I've always wonder if my method was easy or hard.

This is a perfect example of the concept of rounding error. Don't round until you have your final answer. If you round your intermediates, you will have more error in your answer.

Specializes in Adult/ped/neonatal/ICU/Trauma ER nurse.

http://emszone.org/PDF/Drug%20Dose%20Calculations.pdf

maybe this will help you to find the answer.Let me know if needed more help.

You may also want to check out this tutorial:

http://www.dosagehelp.com/

And try out some of the practice questions afterwards. Once you understand how to recognize what the problem is asking for and understand the required formulas, these dosage calculation problems will be pretty straight forward.

Good luck.

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