Medical Dosage Question

nurseprnRN, BSN, RN · May 19, 2012

order 10 mg of a drug, vial in powder form states add 10ml of normal saline and then 2ml=40mg? how many ml will the patient receive?

okay so what i did... 10ml times 40 mg / 2ml

i did 40 x 10 = 400 then i did 10 x2 = 20 then i did 400/20 = 20 ml

not sure if i did this right... please help

ok, let's look at this a bit. questions like this often include information that you don't need to solve the problem, in order to weed out people who can't tell what info they really need. the only information you need here is that 2ml = 40mg. you need to give 10mg. so... it looks like you'd be giving 1/4 of 2ml, or 0.5ml. does that make sense? sometimes drawing a picture is helpful when you do these things. draw a syringe with 2ml in it and write "40mg" next to it. does that help you to see that 10mg is a lot less than 2ml, not a lot more?

question two

order 6mg/m2 if the bsa is 2.2 m2, tablets are 0.003g each, how many tablets should you give..

so i did 2.2 x 6mg=13.2

now i dont know what to do from here? and with the 0.003

let's see what this is. you have to give 6mg for each meter squared of bsa, and you have a patient bsa of 2.2 meter squared, so you want to have a total of 6mg x 2.2, so that's 13.2 mg. so far so good. how many mg is 0.003g? do you know that? ok, 0.003g = 3mg. each tab is 3mg. (more useless info alert: you will never see a tablet labeled 0.003g)

so. each tab is 3mg, and you want 13.2 mg, so how many tabs is that? 13.2 / 3 = 4.4 tabs. see? this question is asking you if you know conversions-- 1 l = 1000ml, 1g = 1000mg ...

Double-Helix, BSN, RN · May 20, 2012

GrnTea is completely right.

I just want to add that, in nursing school, reconstitution problems (where they tell you to add so many mLs to the medication to make the final concentration) used to really confuse me. Then I figured out that it doesn't matter how many mLs they say they added. So whenever you see that, just forget about that number. All you need to know is the final concentration- in this case 40mg/2mL.

I like to cross out the unimportant information and highlight or circle the important parts. Then I rewrite the question using only the important information. So I would rewrite problem #1 to read: "The order is for 10 mg. The medication is supplied as 40mg / 2mL. How many mLs will you give?" Doesn't it seem simpler now?

The trick in question 2 is to convert all your values to the same unit. If you are reading a question and you see a difference in units (like your dose is in mg but your medication is supplied in grams) then the first thing you should do is convert them to the same unit. You'll find the questions much simpler that way.

Esme12, ASN, BSN, RN · May 20, 2012

there are certain essential parts to every equation.......

desired dose:

concentration:

volume on hand:

lb to kg:

looking for:

administration set up:

any conversions necessary?

desired dose x volume on hand

concentration = ml to be given

order 10 mg of a drug, [color=#ffa07a]vial in powder form states add 10ml of normal saline and then 2ml=40mg? how many ml will the patient receive?

weed out the unnecessary information.

desired dose: 10mg

concentration: 40mg

volume on hand: 2ml

lb to kg:n/a

looking for: ml be given

administration set up: n/a

any conversions necessary?n/a

desired dose x volume on hand

concentration = ml to be given

10mg x 2ml

40mg

= 0.5ml.

order 6mg/m2 if the bsa is 2.2 m2, tablets are 0.003g each, how many tablets should you give..

weed out the unnecessary information.

desired dose:

concentration: 0.003g

volume on hand: 1tab

lb to kg: bsa 2.2m2

looking for: 6mg/m2

administration set up: n/a

any conversions necessary? yes

how many mgs are in 0.003 grams? if there is 1000mg to 1 gram......

desired dose x dose/volume on hand

concentration = to be given

1000mg x 0.003g

1g

=3mg per pill

6mg/m2 x 2.2m2

1m2

= ??mg

??mg x 1 pill

3mg

= ?? pills to give

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