Diluting meds??

Hello fellow nurses,
I am a new grad. I will start working soon and I am trying to prepare myself. I know that once I do this over and over again I will have it down but at this point I am getting myself confused with diluting. My question is: if I have a med that is supplied for ex. 50mg/ml. If I dilute it in 10cc, will the diluted dosage be 5mg/ml? I am getting myself soo confused. Also If I have a med that states to dilute 50mg in 20ml and the order to give is 50mg. After I dilute it I am to give 2.5cc. Is this correct or am I going crazy. Is there a calculation for this? It seems if you divide the dosage by the dilution amount you will get the cc amount. Sorry if this is confusing. I tried to look this up in a book and am having a hard time finding it. Thanks ahead for all of your advice. Where was I when this was taught in nursing school??


Jul 17, '09Sweetheart, you are making my eyes cross! When you dilute 50mg of a solute in 20ml of saline, you have 50mg/20ml. If the dose is 50mg, you give the full 20ml. For meds that are already in liquid form, and need to be diluted because they are irritating, or need to be pushed slowly, draw the correct dose of med into a syringe, then empty that syringe into a flush to dilute. If you have an order for 50mg, and the med is 50mg/ml, draw up one ml. Then empty out 1ml of saline from a sterile flush, and squirt it into a flush. LABEL the flush with the med name and dosage in MG. You would have a solution that is 50mg/10ml, or 5mg/ml IF you emptied exactly 1ml of saline. But even if you emptied 2ml by mistake, you would still have the 50mg of med in that flush to give the patient.
The formula I use is one you probably already know:
D/HxV=Q
Where D=dose ordered
H=what you have on hand in MG
V=how many ML
Q=quantity in ML to give
So if a doc orders 30mg Lasix, and you have a vial that is 60ml/2ml, you would use the following calculation:
30/60x2=1(ml to give pt)
I hope this helps and doesn't make everything more confusing.
~Mel' 
Jul 18, '09Quote from mamaRN09I'm not sure about the rest of what your saying but to me it seems that if you have a med. that says "Dilute 50mg in 20ml" and your order is to "Give the patient 50 mg of the drug" then once you add the 50mg of drug to the 20ml of fluid then you would give the patient 20ml. I mean perhaps I'm wrong but that's what it seems like to me.If I have a med that states to dilute 50mg in 20ml and the order to give is 50mg. After I dilute it I am to give 2.5cc. Is this correct or am I going crazy. Is there a calculation for this?
!Chris 
Jul 18, '09Quote from cjcsoon2brnI'm not sure about the rest of what your saying but to me it seems that if you have a med. that says "Dilute 50mg in 20ml" and your order is to "Give the patient 50 mg of the drug" then once you add the 50mg of drug to the 20ml of fluid then you would give the patient 20ml. I mean perhaps I'm wrong but that's what it seems like to me.
!Chris
Yup absolutely. It's like diluting powder doses of some antibiotics into fluid. For example where I work we have the Add Vantage vial/bag system, the powdered antibiotic locks into a bag of fluid. So if I have to administer 1 gram of Ceftriaxone, it is to be diluted in 50 mL of normal saline. Once the medication is mixed you have a solution of 1gram/50mL of Ceftriaxone. 
Jul 20, '09I disagree with the above posts. When you constitute a powder with a diluent,
you end up with more volume than the volume of the original diluent. This is no problem when your powder is intended as a unit dose, however, when you constitute a powder for multiple doses you diluent amount will be less than the target volume of the constituted solution. For example, when constituting 400 mg of Famotidine powder for oral suspension, the target amount (volume of the suspension after constitution) is 50 ml so that each 5 ml is equal to 40 mg of
Famotidine. To do this, you would use 46 ml of purified water.