Can someone help me with this dosage calculation?????

Kristi Lee · May 19, 2005

100 mg : 1mL : 750 mg : X mL multiply 1 x 750 and divide by 100. X= 7.5 mL

this is the way I would figure it. Good Luck!

micky74 · May 20, 2005

thanks so much for helping me

100 mg : 1ml : 750 mg : x ml multiply 1 x 750 and divide by 100. x= 7.5 ml
this is the way i would figure it. good luck!

lifeLONGstudent · Jun 2, 2005

750mg ok kefurox must be prepared. a 1.5g vial of kefurox in powered form is available. directions for reconstitution state: add 14 ml of diluent to yield 100 mg in 1 ml. after reconstituting the drug as directed, how many ml should you withdraw from the vial?

ordered

avail (after you reconstitute) - don't get confused with the reconsitution directions

x = what are they asking for?

o 750mg dose

a 100mg per ml

x = ml/dose to give

ml = 1 ml x 750mg = (750)(1) = 7.5ml/dose

dose 100 mg dose (100)

our school teaches us to use dimensional analysis and here it is in a nutshell:

1. begin with the end in mind: what do you want to end up with? what is the question asking? in this case, they are asking "what dose [ml/dose] are you going to take to the bedside?"

2 - the numberator must match the numberator of what you are looking for. in this case ml.

3. after you set up your first part of the formula, you leap frog the labels - so you match whatever was in the denominator to the numberator

4. cancel out until you end up where you want to be:

5. end where you began. you cannot stop the equation until you get everything to cancel out except what you were originally looking for.

it sounds harder than it is, but look it over as i set it up according to the steps above:

1. begin with the end in mind: what do you want to end up with? what is the question asking? in this case, they are asking "what dose [ml/dose] are you going to take to the bedside?"

ml

dose

2 - the numberator must match the numberator of what you are looking for. in this case ml.

ml = 1 ml

dose 100 mg

3. after you set up your first part of the formula, you leap frog the labels - so you match whatever was in the denominator to the numberator

ml = 1 ml x 750mg

dose 100 mg dose

4& 5. end where you began. you cannot stop the equation until you get everything to cancel out except what you were originally looking for.

** means that you cancel these out - i cannot strike out on the computer

ml = 1 ml x 750** = (1)(750) ml

dose 100 ** dose (100) dose

now that it is all set up, and you are able to end where you began, you just have to calculate the math:

ml = 1 ml x 750mg = (750)(1) = 7.5ml/dose

dose 100 mg dose (100)

lifeLONGstudent · Jun 2, 2005

well, the spacing did not work out when it posted, sorry

if you write it out, then you can make the spacing look right and it will make sense.

lifeLONGstudent

Daytonite, BSN, RN · Jun 4, 2005

I was taught this 30 years ago:

Dose desired divided by dose on hand times amount available = how much you will give.

Dose desired is 750mg Kefurox

Dose on hand is 100mg Kefurox

Amount available is 1mL

Divide 750mg by 100mg and multiply the result by 1mL. The answer is that you will draw up 7.5mL of solution (assuming you reconstituted it as directed with the 14mL of diluent).

You need to know how to do this kind of calculation because you will be doing it more than any other when you give meds and IVs.

Here's a problem for you: You have 500ml of saline with 2000 units of Heparin in it. The doctor orders you to infuse 500 units an hour. What will your infusion rate be in mL per hour?

Dose desired is 500 units

Dose on hand is 2000 units

Amount available is 500mL

Divide 500 units by 2000 units and multiply the result by 500mL. The result is 125mL per hour.

Based on the patients latest PTT the doc decides to change the infusion to some funky number like 650 units an hour. Go for it!