# pitocin calculation

1. OK, fellow RN's, I need your help. I have been running pitocin for 18 years and now when I try to calculate it, I can't find the right formula to make it work. So please show me how to show the math for 10 units or 20 units pitocin added to 1000 ml LR and why 1 milliunit equals 6 ml/hr or 3 ml/hr respectively. Thanks for your help. This is driving me nuts!! SHaron
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2. 11 Comments

3. 20,000 drops in a liter
20,000 miliunits of pitocin in 20 units

20 drops in a ml
20 miliunits in a ml

6 cc/hour =120 miliunits in an hour divided by 60 minutes=2 mu/min

Sheesh I hope that is right...I've never figured it out before even though I administer it frequently on the job ;-(

Someone correct ME if this is not right.

Kim RN CNM
4. OK, I think with the help of your figures, I have it. However, when we add 20units to 1000 ml, 3ml/hr=1 mu/min. (Your calculation came up with 2). We USED to add only 10 units to 1000ml and then each 1mu/min = 6 ml's/hr....so here is where I am getting it from.......
20 units= 20000 milliunits
add this to 1000ml means that each 1ml=20 mu
so if you run at 1ml/hr=20mu/hr but we talk in terms of mu/min when inducing.
I can actually figure backwards easier.....say you want your pit at 5 mu/min take that times 60 to get mu/hr which is 300mu/hr and we know that 20 mu=1ml so 15 ml/hr would equal 5 mu/min. OK do I have everyone confused?? Anyway, I have it in my head now, just need to put it on paper so I can show new hires how to calculate. WOW that was way to taxing! Just hate to not be able to explain it to someone. Thanks, SHaron
5. Um . . . . we just have a sheet of paper with the numbers already figured out.

steph
6. Boy do I feel dumb!

We don't mix our own pit, it is premixed at 20 units/L by pharmacy and stocked for us.

We also have "Guardrails Drug Library" in our pumps. So I just pick the drug, double check the strength and tell the pump how many milliunits/min to run.
7. This is the formula I've always used, hope it helps.

Step 1: Determine the concentration of Pitocin/mL:

1 unit = 1,000 miliunits
10 units = 10,000 miliunits

10,000 miliunits = 10 miliunits (10 miliunits/1 mL)
1,000 mililiters 1 mililiter

Step 2: Calculate (at this concentration) how many mL/hour will be given:

1 miliunit/minute = 60 milliunits/hour (1 miliunit X 60 minutes/hour)

Step 3:Using ratio & proportion to calculate mL/hour:

10 miliunits:1 mL = 60 miliunits: X mL

10X = 60

X = 6 mL/hour
Last edit by Leda on Mar 22, '06
8. i am in an RN program right now and am having a terrible time with the math. If someone could help me to set up a formula for this problem that would be fantastic!
You need to set up a Pitocin drip with a concentration of 10U in 1000ml. The vial has a concentration of 10U/1ml. How many ml's do you put in the bag?
9. You would put the contents of the 10U vial into the liter bag of LR. That is, 1ml Pitocin into the liter of LR. Yes, that would give you 10U in 1001 ml LR if the bag of LR really only had 1000ml in it, but the bags aren't that exact. They almost all have more than 1000ml in them.

If you're mixing Ephedrine from a vial that has 50mg in 1ml and you want 5mg/ml, you would add the 1ml of Ephedrine to 9ml of saline. This would give you 50mg in 10ml or 5mg in 1ml. With this much smaller volume you can and must be more exact. Where the cut off point is between being really exact and being close, I don't know.

You could always pretend that the LR bag has only 1000ml in it and remove 1ml before adding the 1ml (10U) of Pitocin. Since that would involve puncturing the bag twice and increasing the risk of contaminating the bag, I don't think it's worth the effort.
10. Leda explains it well. Use that to explain to new nurses what the concentration is.

If you have 10,000mU in 1000ml, you have 10mU in 1ml or 1mU in 0.1ml. If you have 20,000mU in 1000ml, you have 20mU in 1ml or 2mU in 0.1ml or 1mU in 0.05ml.

I got all this, but it took me forever to figure out where the 6 came in. It come in because there are 60 min in an hour and you program the pump in ml/hr even though the dose is given in mU/min.

If you want 1mU/min, you want 60mU/hr. Sixty mU is contained in 6ml of 10U/1000ml solution or 3ml of the 20U/1000ml solution.

The difficulty of figuring this out at 3am, or even remembering the 6X table at that hour of the morning is why it is recommended by various authors to use a 30U/500ml concentration. Work it out and you'll see why it's a much safer concentration to use.
11. Quote from ragingmomster
Boy do I feel dumb!

We don't mix our own pit, it is premixed at 20 units/L by pharmacy and stocked for us.

We also have "Guardrails Drug Library" in our pumps. So I just pick the drug, double check the strength and tell the pump how many milliunits/min to run.
Thank goodness for these! We have the same type of pump!
12. We used to do 10 units in 1L, and it was 1mu = 6ml/hour. It was determined that it was unsafe to mix our own, and now we use premixed bags - 30 units in 500ml, so it's a 1:1 ratio, which is very nice.
13. I like our mix, 30units in 500 ml of NS. NO guess work. 1 to 1.

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