Pharmacy Dosage Simple Calculations- Please Need Help Now to learn

[PrePharmStu2009]

Questions
1. What does D5 1/2 NS mean?

I know that 5 % dextrose is 5 g/100 ml right? so 1/2 NS does that imply 77 meq/ 1000 ml NaCl concentration?

What if it is 1/4 NS 500 ml... What is the concentration the of Na Cl then

Questions
2. Sodium Chloride comes in a concentration of 4 mEq/ml. How much NaCl must you add to sterile water to make the following solutions:

1/4NS 250 ml NS 1000 ml , 1/2 NS 500 ml, 1/2 NS 1000 ml, 1/4 500 ml, NS 250 ml, NS 500 ml

How do you do this problem? If someone can explain me the basic steps and show an example. How are concentrations based on volume. So for 1/4, 250 will concentration be 1/8 * (154) since 154 is normal and volume is reduced by 1/4 of 1000, so 1/4 NS???

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[type b pharmD]

Please help me with these calculations. I haven't started pharmacy school yet but I got an internship at a hospital. We have to learn how to do these calculations within the next day. Please help me learn this and explain this to me.

Questions
1. What does D5 1/2 NS mean?

I know that 5 % dextrose is 5 g/100 ml right? so 1/2 NS does that imply 77 meq/ 1000 ml NaCl concentration?

What if it is 1/4 NS 500 ml... What is the concentration the of Na Cl then

Questions
2. Sodium Chloride comes in a concentration of 4 mEq/ml. How much NaCl must you add to sterile water to make the following solutions:

1/4NS 250 ml NS 1000 ml , 1/2 NS 500 ml, 1/2 NS 1000 ml, 1/4 500 ml, NS 250 ml, NS 500 ml

How do you do this problem? If someone can explain me the basic steps and show an example. How are concentrations based on volume. So for 1/4, 250 will concentration be 1/8 * (154) since 154 is normal and volume is reduced by 1/4 of 1000, so 1/4 NS??? I am confused thank you

d5 1/2 NS = a solution containing 0.45% sodium chloride and 5% dextrose in sterile water.

As for the making the bags. Just remember and think carefully about this .

NS = 0.9% nacl = 154meq/L
1/2NS = 0.45% nacl = 77meq/L
1/4NS = 0.225% nacl = 38.5meq/L

You dont need any more help than this. If you think hard and carefully about it, you will learn better and teach yourself new things.

Calculating % to meqs conversions is annoying and for me takes like 10 minutes of reasoning through chemistry formulas and moles and milimoles. Most pharmacists I know recommend just memorizing meq's/L for some standard solutions.

Oh, and btw: NS = normal saline. (0.9%, which is basically the same tonicity as the body's fluids.) 1/2NS is half of that, 1/4NS, 1/4, etc, etc, etc.

 

[PharmDstudent]

As for the making the bags. Just remember and think carefully about this .

NS = 0.9% nacl = 154meq/L
1/2NS = 0.45% nacl = 77meq/L
1/4NS = 0.225% nacl = 38.5meq/L

Thanks! I had to use those today.