PLEASE HELP! Diluent problems!

by AshRNAthena (New) New

Hi everyone. I'm new here and hoping for some help! I am a new RN and am getting ready to start my first job. We received a study guide for a test we will have to take IN THREE DAYS and I HAVE NO IDEA how to do some of these problems. I am so stressed out already. :uhoh3: PLEASE HELP!

1. The physician has ordered potassium penicillin G 125,000 units by injection for your patient. You have availablea vial of powdered potassium penicillin G labeled 1,000,000 units. Please solve one of the dilutions using the label below.

Preparation of solution:

Diluent added Final Concentration

9.6 ml 100,000 units/ml

4.6 ml 200,000 units/ml

3.6 ml 250,000 units/ml

I only need to know how to do one, but I don't know how to do ANY!

2. Ampicillin 1.5gm is ordered every 4 hours. You add 6.8 mL sterile H20 as a diluent to the 2 gm vial creating a solution concentration of 250 mg/ml. How many mls are needed for a 1.5 gm dose?

3. The physician has ordered potassium penicillin 3,000,000 units by injection for your patient. You have available a vial of powdered potassium penicillin G labeled 5,000,000 units.

Preparation of solution:

Add diluent: Total concentration

23 ml 200,000 units/ml

18 ml 250,000 units/ml

8 ml 500,000 units/ml

3 ml 1,000,000 units/ml

I only have to choose one diluent and one concentration, but I don't know WHAT to do!

ANY HELP IS SO APPRECIATED! I feel so dumb and unprepared!!:confused:


Specializes in MICU for 4 years, now PICU for 3 years!. Has 7 years experience. 459 Posts

For all of these, remember your equation

(Ordered Dose/What you have)XmL

So for the first question, if you chose to use the 9.6mL dilutent, the equation would look like this:

(125,000 units/100,000 units)X9.6 mL

I use that equation often... its a good one to know. Good luck!


277 Posts

Old post on a dead board, but just for giggles:

1. I'd go with the bottom dilution to avoid having to give multiple shots. If 3.6 mL has 250K units and 125K units are ordered, give 1.8 mL.

2. 250 mg/mL = 0.25 g/mL = 1.5 g/6 mL Give 6 mL.

3. Use the bottom dilution again for the same reason as in #1.

1M units/mL = 3M units/3 mL. Give 3 mL.