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drug calculations

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BWORN BWORN (New) New

I need some help w/drug calculations! Can someone show me how to do the following?

Dopamine 500 mg/500 ml to run at 5mcq/kg/min. Pt wt is 80kg. What would the flow rate in ml be?

Dopamine 500 mg/500 ml to run at 5mcq/kg/min. Pt wt is 80kg

That's a weird Dopamine mix. Ours is normally 400mg/250ml or 800mg/250ml.

But to answer your question you take 500mg/500ml to get mg/ml. Then divided it by 60 to get mg/ml/min. Then multiply it by 80kg to get mcg/ml/min. That number you divide by 5mcg/kg/min to get you drip rate.

500/500 x 1000, divide answer by 60, then--divide by 80, gives you a constant(K=0.208) 5mcg divided by constant = 24.038 cc or 24cc/hr. Thats how I do it.

Thanks! I may be dense or a little sleep deprived but the ratio is 1:1 divided by 60 is .02 X 80 Kg = 1.6 divided by 5mcq/kg/min =.32 X 60 = 19.2....is that correct?

Brownms46

Specializes in Everything except surgery. Has 27 years experience.

Here is how I did it.

500/500= concentrations 1000 mcg/ml 80kg x 5mcg/kg/min =400 mcg/min 400/1000 = 0.4mcg x 60 min= 24micro gtts/min or on a pump 24 ml/hr right???

Thanks Brownie! I've always used the computer to figure out the drip rates for different drugs. I've forgotten how to set up the formulas. I want to thank everyone who's responded to my question.

Bworn

Brownms46

Specializes in Everything except surgery. Has 27 years experience.

You're very welcome BWORN :D! I wouldn't have remember either if I hadn't been taking the dreaded drug tests to work agency..UGH!

Doing the happy dance!

Just had our final today in Pharmacology I - Calculations and aced it! The 100 I made on the final gives me a 97 for the course

I know that Calc is the easy part but still I take the lil' victories as they come!

Now . . . . If I can just do as well in Pharmacology II . . . . . .

Brownms46

Specializes in Everything except surgery. Has 27 years experience.

congrats bedpan!! you just go on with your bad self now

good luck!

bedpan, congratulations!!!!!!!!!

Thanx Brownms46 and guru

neneRN, BSN, RN

Specializes in Emergency, Trauma. Has 8 years experience.

All mcg/kg/min gtts can be calculated using the same formula- I write this down for every new nurse I precept to stick to the back of their badge for easy reference.

MG of drug x 1000=

Divided by amt of fld=

divided by 60 (min)=

divided by kg weight= DF(your dosage factor)

mcg/kg/min divided by DF=cc/hr

Be sure to write down your dosage factor, so that when you need to titrate, you don't have to repeat all the steps.

To see this in action:

I have 400 mg of Dopamine in 250 cc NS. I want to start my drip at 10 mcg/kg/min. My pt weighs 70 kg.

400mg x 1000= 400,000

400,000 divided by 250 cc= 1600

1600 divide by 60 minutes= 26.7

26.7 divided by 70 kg = 0.38 (DF)

10 (mcg/kg/min) divided by 0.38 (DF) = 26 cc/hr

Now let's say I want to titrate that same drip up to 15mcg/kg/min, I would simply plug my DF into the last equation (mcg/kg/min divided by DF = cc/hr)

15 divided by 0.38 = 39 cc/hr.

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