Drug Math Answer Key

Answers to part II
1. 500 mcg / 50 ml
Answer: 10mcg/ml

25 mg / 250 ml (first convert this to mcg)
Answer: 100mcg/ml

3. 10 mg / 2 ml
Answer: 5mg/ml

4. 500 mg / 250 cc
Answer: 2mg/ml
Answers to part III
mini drip = 60gtts/ml
macro drip = 10gtts/ml

1. Your dose is 20mcg/kg/min and your concentration is 500mg in a 50cc vial. Use a mini drip.
Plug your numbers into the formula. Remember, the time portion of the dose goes on the bottom.
20mcg/kg x 70kg x 60gtts/ml
500mg/500ml x min.
First convert concentration to mcg because the dose is in mcg
20mcg/kg x 70kg x 60gtts/ml
500,000mcg/500ml x min.
Next reduce your concentration
20mcg/kg x 70kg x 60gtts/ml
1000mcg/1ml x min.
Next, cross out a zero up top for every zero on the bottom.
20mcg/kg x 70kg x 60gtts/ml
1000mcg/ml x min.
Then cross out every variable that repeats itself
20mcg/kg x 70kg x 60gtts/ml
1000mcg/ml x min.
Then rewrite the formula without all the stuff you just crossed out.

2 x 7 x 6 gtts

Now you know your answer is going to be gtts/min. from here just multiply what is left.
2 x 7 = 14 & 14 x 6 = 84
Answer: 84 gtts/min
now work thatdown to something you can manage
It's almost 3 gtts every 2 seconds

2.Your dose is 10mcg/min and you have a 250cc vial with 25 mg. Use a mini drip.

Answer: 6gtts/min (better use a IV pump)

3.Your dose is 2mcg/min and you put 1mg in a 250cc bag. Use a mini drip.

Answer: 30 gtts/min. (1gtt/2sec.)

4.Your dose is 150mg/10min you have a 100cc bag and a macro drip.
This was a trick question. For this one, all you have to worry about is getting 100ml of fluid in over 10 min. using a 10gtts/ml drip set. So your dose is 100 x 10. The 100 comes from the 100ml portion and the 10 comes from the time. Giving a certain amount of fluid over a time period is slightly different. You can use the formula if you plug it in correctly, but I will show easier ways in further posts.
100 x 10 x 10gtts/ml
100ml x min.
Answer: 100ml/min. (about 3gtts/2sec.)

5.Your dose is 0.25mg/kg for a 132 pound and you have a 5cc vial with 25 mg. This is a common dose for Cardizem. If you divide your patient's weight(in kg) by 4 you will have your dose in mg. Then divide by 5 because for every 5mg its one ml.
60kg/4 = 15
15mg/5 = 3
Answer: 3ml (15mg)

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