Help with dosage calculation problem

[justjj01]

I have a question. I am working on Reconstitution of Solutions. Working on the part where you calculate the amount of solute needed....I know the formula

Desired strength x amount of desired solution = Solute (solution to be dissolved)

Ordered amount - Solute = Amount of solvent needed

OK, here is the question..

Order 1/3 strength Ensure 900mL by NG tube over 8 hours

I can work that out and get 600mL solvent needed

Next questions....

Order 3/4 strengh Isomil 4oz q4h for 24 hours

I worked this out and got 30ml solvent needed....but the anwer in the book is 180mL (which is 6 feedings)

Why is it figured per doage on the first question and then for 24 hours on the second question?

Thanks

[ParkerBC,MSN,RN, PhD, RN]

Do the directions specify the amount needed per dose or over a course of a certain time? Generally that is how to come up with the answers.

[Esme12, ASN, BSN, RN]

This is an excellent site/calculator......

http://www.dosagehelp.com/

[loriangel14, RN]

Because they were two different orders.

[Anothertry]

Can you explain how you came up with the second answer? How did you get 30 mL?

[Thujone]

"Order 3/4 strengh Isomil 4oz q4h for 24 hours

I worked this out and got 30ml solvent needed....but the anwer in the book is 180mL (which is 6 feedings)"

1. 4 oz x 30 = 120 ml

2. 120 ml x .75 = 90 ml

3. 120 ml - 90ml = 30 ml

4. 24 hours / 4 hours = 6 dosages

5. 6 dosages x 30 ml per dose = 180 ml

[Anothertry]

Thanks Brian for the break down. :)