Pharmacy Tech
posted by Isha .
Rx: Prostaglandin E 10mcg/mL
If the stock container of prostaglandin E is 100 mg/mL, how many 9mL dilutions are required to prepare the ordered concentration?

You are diluting 100m/10mc times, or 100/.01 = 10000 times. I am not familiar with a procedure called 9 ml dilutions. IF YOU MEAN 9ml water to 1ml of stock, then to get 10,000 you need to do it..
first time: 10:1
second time: 100:1
third time:1000:1
fourth time:10 000 :1 you are done. 
Same procedure as above, except first you need to convert the stock container of 100 mg/ml to the mcg/ml you need to satisfy the prescription. So to do that you do a ratio like that listed above, except you start off with 100,000 mcg (after converting 100 mg to micrograms). Then from there you do as follows:
100,000:1
10,000 :1
1,000 :1
100 :1
And there's your answer, it takes 4 times to get to the desired dilution.