Formula to use


Hi could some one show me the formula for this question pls

Vasopressin 5 units IM stat and repet 4h prn Supply 1ml vial that indicates 20mg/ml which of the following would deliver one dose






Specializes in L&D/Maternity nursing.

I am a ratio and proportion gal.

Dose ordered=5 units (are you sure you didnt mean mg instead of units?)

Dose on hand=20 mg/mL (or was it 20 units/mL and not mg/mL?)

Anyways for sake of calculating it out:

5/x mL=20/1 mL----> 20x=5 will give you x=0.25mL

crb613, BSN, RN

1,632 Posts

Specializes in Med Surg/Tele/ER. Has 7 years experience.

I do DA or dose ordered/dose avail X ml for the short stuff. Did you mean mg instead of units? If so.....

5mg/20mg X ml=0.25ml (5/20=0.25 X 1ml= 0.25)

Daytonite, BSN, RN

4 Articles; 14,603 Posts

Specializes in med/surg, telemetry, IV therapy, mgmt. Has 40 years experience.

order: vasopressin 5 units im stat and repeat in 4hrs prn.

supply: 1ml vial that indicates 20 units/ml.

which of the following would deliver one dose?

answer 0.5 ml, 0.25 ml

use the formula:
dose desired
divided by
dose on hand
multiplied timesthe
amount that the dose on hand comes in
the amount to give.
5 units
(dose desired)/
20 units
(dose on hand) x
1 ml
(amount that the dose on hand come in)
0.25 ml
(amount to give)

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