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Pharmacy Flow rate question

by arch
(austin, tx)

You have a solution of Drug H/100,000-U/L, and an infusion apparatus labeled 60gtt/ml. The flow rate required to deliver a dose of 20U/min would be:

A. 3 gtt/min
B. 12 gtt/min
C. 15 gtt/min
D. 20 gtt/min

Please help how to do this in detail? Thanks.

Comments for Pharmacy Flow rate question

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set it up with info given in problem like this:
by: Becky

1L/100,000units x 20units/min x 1,000ml/1L x 60gtts/1ml will make all the units cancel except what you want--drops per min. So, 1,200,000 gtts/100,000 min equals 12gtts/min

pharmacy math
by: Jerry

First, convert to mL's:
100,000u/per Liter = 100u per mL.

From here, I'd use an equation:

On one side:

100u (in a mL)
60gtt (in a mL)

On the other side,
equate it to how many units needed.

100u - - 20u
------ = ------
60gtt - - - X

That would give you gtt/min

Kind of an unorthodox way, but it's not the most straightforward question.

attempted solving
by: lynn

first convert 100000U/L in ml
i.e 1000ml(1L)---100000U

then it is said infusion is set at 20U/min
therefore 100U will infuse in 5mins(cross multiply)

Given the formula flow rate=vol*drop factor*1hr divided by hr*1ml*60mins with vol=1ml drop factor always assumed to be 60gtt/ml(unless stated) and hr=1/12hr(5mins)
the flow rate=12gtt/min

Flow rate question
by: Brad Wojcik, Pharm D

I like to start a problem like this off by writing down the units of the answer and the given so I know what I need to do. We are told that the IV is to run at 20 u/min and the units of the answer will be gtt/min. 20u/min = gtt/min. Now we can see that we only need to change 20 u into drops. We don't have to do anything with the min. The ratios involved which are our tools to change the units are 100,000 u/L, 60 gtt/mL. We have to supply our own ratio of 1000 ml/L.
20 u/min (1L/100,000 u)(1000 mL/L)(60 gtt/mL) = 12 gtt/min.

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