Drug Calculation question here?

hrtprncss · Aug 31, 2005

that doesn't make sense whatsoever, unless the soln is .5 cc/1 gm of rx in the vial then u give 1 cc after dilution. but u said it was powdered. i think it's a typo, unless for some unlikely reason that you would yeild a total of 2 cc solution after mixing a powdered solution with 1.5 cc saline.

nursemomruns · Aug 31, 2005

The volume of the powder adds the other .5 ml.

truern · Aug 31, 2005

Ignore the dilutant.

It's still 1000mg/2mL : 500mg/xmL

1000x=1000/1000=1mL

Daytonite, BSN, RN · Aug 31, 2005

You will give 1mL. Dose desired is 500mg divided by dose on hand which is 1 gram (or 1000mg) multiplied by the amount on hand which is 2mL.

I've been a hospital nurse for 30 years, trust me I've given you the right answer.

hrtprncss · Aug 31, 2005

it's obvious you'll give 1cc if it's 2cc/gm. but she has a gives a given specific volume to start with. like i said if the solute is going to add make it a 2 cc solution then it's one cc, though alot of meds that are hydrophyllic would produce the same amount of solution as u first start with, hence making it an unworkable equation.

Nurseismade RN · Aug 31, 2005

You will give 1mL. Dose desired is 500mg divided by dose on hand which is 1 gram (or 1000mg) multiplied by the amount on hand which is 2mL.
I've been a hospital nurse for 30 years, trust me I've given you the right answer.

That's how I calculated it also....I love the formula approach. :) Just a quick question...maybe this only applies to pills...but is the 2ml considered on hand or volume. I usually use D/H x V= Amount to be given

twinmommy+2, ADN, BSN, MSN · Aug 31, 2005

*the light dawns in my head*

I knew I wasn't seeing something correctly. Thanks so much for all the help! You all have been great. Its like you're looking for the key that you're eyes won't see right under your face till someone points it out.

It is all so simple now hehe.

Daytonite, BSN, RN · Sep 1, 2005

The amount is what the dose on hand is in, in this case 2mL. It works for pills also. If you have to give Benadryl 50mg and you have 25mg tablets, the formula is 50mg (dose desired) divided by 25mg (dose on hand) multiplied by the amount the 25mg is in which is one tablet. Answer: 2 tablets.

There was some concern in earlier posts about the amount of dilutent being used. Not to worry. The drug companies include the amount of the powder in the vial along with the amount of dilutent the label tells you to add. This has all been very accurately worked out by the manufacturer. In actual practice you would find that you would be able to draw a full 2ml up into a syringe in the case of Staphlocyllin. There might be even a teensy little bit more left over.

A common drug we used to have to mix and do some dose calculation on was Solu-Medrol or Solu-Cortef. The dilutent in their case are included with the vial. You push a stopper at the top of the bottle down which forces another stopper between the top and bottom half of the vial to release the dilutent into the powder. We would often have to calculate a dose of 125mg for IV push in a resulting solution (after dilution) of 200mg per 2 mL. The correct amount would be 1 and 1/4 mL. Another liquid medication you can play around with in practicing these problems is Heparin. Mostly, the pharmacists mix it into an IV for you, but we often had to mix it at 2am in the morning if the pharmacy was closed. Heparin (for mixing) comes in a vial of 10,000 units in 1mL. You need to mix 8,500 units into a 500mL bag of saline. The calculation is not that hard with the formula. First, don't let the 500mL bag of saline get you off track. It has nothing to do with how much Heparin you are going to use. The problem is solved by calculating the dose desired (8,500 units) divided by the dose on hand (10,000 units) multiplied by the amount the 10,000 units is in (1mL). The answer is you would mix 0.85mL of the Heparin solution into the bag of saline. If you are to run it at 600 units and hour, the hourly rate can be calculated the same way. Dose desired would be 600 units divided by the dose on hand (8,500 units -- now you're working with the IV bag) multiplied by the amount the 8,500 units is in which is 500 mL. The answer is 35mL per hour (that's rounded off).

Hope that helps you all.

crb613, BSN, RN · Sep 1, 2005

You will give 1mL. Dose desired is 500mg divided by dose on hand which is 1 gram (or 1000mg) multiplied by the amount on hand which is 2mL.
I've been a hospital nurse for 30 years, trust me I've given you the right answer.

Yes its right. You have to convert 500mg to grams=0.5g/1g=0.5gX2ml=1ml.

The rest of the stuff in the problem is just junk.