Dimensional Analysis and Factor Labeling relies on 3 factors to calculate dosages:
1. The drug label factor is called V, the medication that the nurse must administer
2. The conversion factor lets nurses set up the equation with the conversions needed to calculate the dose
3 The drug order factor indicates the desired dose to be given
What is the Dimensional Analysis and Factor Labeling method for medication dosage?
X = V/H (drug label) x C(H)/C(D) (conversion factor) x D/1 (drug order)
Ratio and Proportion method continued (Injectable medication)
H= 4mg, V= 1mL, D= 2mg, X= amount to administer
4 : 1 :: 2 : x (multiply means and extremes)
4x :: 2
x :: 1/5
0.5 mL administered to patient
Ratio and Proportion method continued (solid oral medication)
H= 250mg, V= 1 capsule, D= 500mg, X= number to administer
250 : 1 :: 500 : x (now multiply means and extremes)
250x :: 500
x :: 2
2 capsules to be administered
The order is for amoxicillin 1 g by mouth. Available is Amoxicillin 250 mg per 5 mL . How many mL do you give the patient?
Answer 20.
H= 250mg, V= 5mL, D= 1g, C= 1000mg/1g
X= 5mL/250mg x 1000mg/1g
X= 0.02 x 1000
X= 20
20mL to be given to patient
What are the 3 main methods of medication dosages?
1. Formula method
2. Ratio and proportion method
3. Dimensional analysis method
Ratio and Proportion method continued (Liquid Oral Medication)
H= 250mg, V= 5mL, D= 375mg, X= amount to administer
250 : 5 :: 375 : x (multiply means and extremes)
250x :: 1,875
x :: 7.5
7.5mL administered to patient
Dimensional Analysis without using conversion factor
H= 250mg, V= 1 capsule, D= 500mg, X= number of capsules to administer
X(capsules) = 1 cap / 250mg x 1/1 x 500mg/1
X(capsules) = 0.004 x 1 x 500
X = 2
2 capsules administered to patient
Dimensional Analysis using a conversion factor (solid oral medication)
D= 0.5g, H= 250mg, V= 1 tab, C= 1000mg/1g
X(tabs) = 1cap/250mg x 1000mg/1g x 0.5g/1
X(tabs) = 0.004 x 1000 x 0.5
X = 2
2 tablets to be administered
Which symbol is used to identify unknown terms in a proportion?
